The present disclosure relates to the technical field of multi-rotor aircrafts, in particular to an inner-cobweb-like compact-structured multi-rotor aircraft with multi-shaft dislocation layout.
The most common multi-axis rotor aircraft in the prior art is of 4-shaft 8-propeller and 8-shaft 8-propeller designs. There are various frame structures such as an X type, an H type, and a Y type according to different design requirements and layout conditions.
A 4-shaft 8-propeller multi-rotor aircraft is of a coaxial design. Power shafts of motors corresponding to four propeller blades on the upper layer and power shafts of motors corresponding to four propeller blades on the lower layer are collinear in a one-to-one correspondence manner. A propeller blade pitch between the upper and lower propeller blades is smaller. The upper and lower propeller blades overlap in a projection direction, so that the propeller efficiency is lower. In addition, in this multi-rotor aircraft, a frame is of a cantilever structure, so that the rigidity of a fuselage is poor.
An 8-shaft 8-propeller multi-rotor aircraft is of a non-coaxial design. The eight propeller blades are arranged at intervals on the same plane. The aircraft is larger in overall size, larger in volume, heavier and higher in flight resistance. In addition, similar to the 4-shaft 8-propeller multi-rotor aircraft, the frame of this multi-rotor aircraft is also of a cantilever structure, so that the rigidity of the fuselage is also poor.
For a multi-rotor aircraft with a high loading requirement, such as 10-shaft and 12-shaft aircrafts, propeller blades are usually arranged at equal intervals in the prior art, and centers of the propeller blades are located on the same circle along the projection direction. In such setting, in order to meet the increasing loading requirements, the following two methods are usually used: (1) enlarging the aircraft proportionally, that is, increasing the length of a force arm (an arm connecting the propeller blades and the center of the frame) and increasing the wheel base; (2) increasing the number of force arms, that is, increasing the number of propeller blades. Due to equal-interval arrangement, in order to prevent collisions between the propeller blades, the volume of the multi-rotor aircraft is usually relatively large. The above two methods will inevitably increase the volume and weight of the aircraft a lot.
In addition, in the projection direction, a plurality of propeller blades are arranged on the same circle. The transportation of the aircraft will be more inconvenient when the volume of the aircraft becomes larger and larger to cause conventional transportation equipment cannot be used for transportation.
In summary, the multi-rotor aircraft in the prior art has the disadvantages of high flight resistance, large volume, poor fuselage rigidity, and low propeller efficiency under the same loading capacity.
The technical problem to be solved in the present disclosure is to overcome the disadvantages that a multi-rotor aircraft in the prior art has high flight resistance, large volume and low propeller efficiency under the same loading capacity, and provide a multi-rotor aircraft with multi-shaft dislocation layout.
The present disclosure solves the above technical problems through the following technical solutions:
A multi-rotor aircraft with multi-shaft dislocation layout includes a frame, a plurality of upper-layer power sources and a plurality of lower-layer power sources. The multi-rotor aircraft further includes:
a plurality of upper-layer propeller blades, the plurality of upper-layer propeller blades being disposed at intervals and being connected to the upper side of the frame through the plurality of upper-layer power sources; and
a plurality of lower-layer propeller blades, the plurality of lower-layer propeller blades being disposed at intervals and being connected to the lower side of the frame through the plurality of lower-layer power sources;
the plurality of upper-layer propeller blades and the plurality of lower-layer propeller blades are staggered along a projection direction of the frame;
the centers of the plurality of upper-layer propeller blades and the centers of the plurality of lower-layer propeller blades are located on the same flat geometric figure along the projection direction of the frame.
In this solution, the upper-layer propeller blades and the lower-layer propeller blades are staggered, so that a propeller blade pitch between the upper-layer propeller blades and the lower-layer propeller blades is relatively large; the central axis of the upper-layer power sources and the central axis of the lower-layer power sources are not collinear or do not overlap; and the upper-layer propeller blades and the lower-layer propeller blades have a relatively small overlap area in the projection direction of the frame. Compared with a 4-shaft 8-propeller coaxial multi-rotor aircraft in the prior art, the multi-rotor aircraft with multi-shaft dislocation layout is that the upper-layer propeller blades and the lower-layer propeller blades have a relatively large vertical height difference and generate a relatively low mutual disturbance, and the propeller efficiency is higher; and a correspondingly required propeller rotation speed is lower, and the noise is lower. Compared with an 8-shaft 8-propeller multi-rotor aircraft in the prior art, the multi-rotor aircraft with multi-shaft dislocation layout is that the overall size is greatly reduced, and the weight, the volume and the flight resistance of the fuselage are also obviously reduced.
In addition, the centers of the upper-layer propeller blades and the centers of the lower-layer propeller blades are located on the flat geometric figure along the projection direction of the frame. That is, a lateral length of the multi-rotor aircraft is greater than a longitudinal length. In case of a high loading requirement, the multi-rotor aircraft does not need to be enlarged proportionally, but the number of shafts can be increased from the center of the frame to a corresponding narrower section in the flat geometric figure. For example, an 8-shaft multi-rotor aircraft is changed into a 10-shaft or 12-shaft multi-rotor aircraft to meet the loading requirement, which has less influence on the volume and weight of the multi-rotor aircraft. In addition, the centers of the upper-layer propeller blades and the centers of the lower-layer propeller blades are located on the flat geometric figure, so that the multi-rotor aircraft has a relatively low requirement for transportation equipment, and is convenient to transport.
In summary, compared with the multi-rotor aircraft in the prior art, the present disclosure is that on the one hand, under the same loading capacity, the flight resistance and the volume of the multi-rotor aircraft with multi-shaft dislocation layout are obviously reduced, and the propeller efficiency is improved; on the other hand, the multi-rotor aircraft can meet a higher loading requirement in the case of less influence on the volume and weight of the multi-rotor aircraft, and the multi-rotor aircraft has a relatively low requirement for transportation equipment.
Preferably, the geometric figure is an axisymmetric figure.
In this solution, by the adoption of the above structural setting, the multi-rotor aircraft is convenient to manufacture and assemble.
Preferably, the centers of the plurality of upper-layer propeller blades and the centers of the plurality of lower-layer propeller blades are located on the same rectangle or ellipse along the projection direction of the frame.
Preferably, an overlap area between any adjacent upper-layer propeller blade and lower-layer propeller blade is equal to an overlap area between another adjacent upper-layer propeller blade and lower-layer propeller blade along the projection direction of the frame.
In this solution, for any two groups of adjacent upper-layer propeller blades and lower-layer propeller blades, the overlap areas of the upper-layer propeller blades and the lower-layer propeller blades are equal, so that a lift generated by each propeller blade (the upper-layer propeller blade or the lower-layer propeller blade) in a lift system of the multi-rotor aircraft is the same, which is conductive to guaranteeing the performance of the multi-rotor aircraft. On the basis that the centers of the upper-layer propeller blades and the centers of the lower-layer propeller blades are located on the same flat geometric figure, if the overlap areas of the upper-layer propeller blades and the lower-layer propeller blades are equal, a plurality of included angles encircled between the plurality of upper-layer propeller blades and the plurality of lower-layer propeller blades (included angles are encircled between the adjacent upper-layer propeller blades and lower-layer propeller blades) are not completely the same, that is, the plurality of upper-layer propeller blades and the plurality of lower-layer propeller blades are disposed at unequal intervals.
Preferably, at least five upper-layer propeller blades and at least five lower-layer propeller blades are provided.
Preferably, a dislocation angle is formed between a connecting line of the center of any upper-layer propeller blade and the center of the adjacent lower-layer propeller blade and a horizontal plane of the frame, and the dislocation angle ranges from 0 to 89 degrees.
In this solution, by the adoption of the above setting, the relative positions of the upper-layer propeller blades and the lower-layer propeller blades can be adjusted according to loading and layout requirements.
Preferably, the frame includes:
a frame center portion;
a plurality of connecting arms, the connecting arms having first ends and second ends along an extending direction, the first ends of the plurality of connecting arm being connected to the frame center portion, and the second ends of the plurality of connecting arms being correspondingly connected with the plurality of upper-layer power sources, the plurality of upper-layer propeller blades, the plurality of lower-layer power sources and the plurality of lower-layer propeller blades; and
at least one reinforcing arm, an accommodating region being formed between the second ends of any two adjacent connecting arms, and at least one of the accommodating regions formed between the plurality of connecting arms being provided with each reinforcing arm.
In this solution, by the adoption of the above setting, the corresponding connecting arms are no longer of the cantilever structure due to the arrangement of the reinforcing arms, but the reinforcing arms and the adjacent connecting arms can encircle a structure similar to a triangle to facilitate improving the rigidity of the fuselage and reducing vibration generated by deformation of the aircraft.
Preferably, the connecting arms are detachably connected or fixedly connected to the reinforcing arms and the frame center portion to form an integrated structure;
or, the connecting arms are integrated with the reinforcing arms and the frame center portion.
In this solution, the integrated structure is convenient for fast assembling of the aircraft. By the adoption of integration, connecting structures are eliminated, so that a relatively tedious connecting process is eliminated, and it is conductive to reducing the overall weight of the aircraft and then reducing the flight resistance of the aircraft.
Preferably, the multi-motor aircraft includes an upper-layer component and a lower-layer component which are detachably connected;
the upper-layer component includes the frame, the plurality of upper-layer propeller blades, the plurality of upper-layer power sources, the plurality of lower-layer propeller blades and the plurality of lower-layer power sources;
the lower-layer component includes an undercarriage and an operating load unit which are connected to each other; the operating load unit includes a load and an energy load module; the energy load module is used to supply power to the upper-layer power sources and the lower-layer power sources; the load and the undercarriage are connected to the energy load module; and the energy load module is detachably connected to the lower side of the frame.
In this solution, by the adoption of the above setting, the multi-rotor aircraft mainly includes the upper-layer component and the lower-layer component. On the one hand, the upper-layer component and the lower-layer component can be transported independently, so that a requirement for transportation conditions are relatively low; on the other hand, after the upper-layer component and the lower-layer component are connected together, more convenient and faster assembling of the multi-rotor aircraft can be realized, which is conductive to reducing the preparatory work before take-off and improving the fast reaction performance of the multi-rotor aircraft. In this solution, the energy load module and the undercarriage are assembled together and arranged below the frame.
Preferably, the multi-motor aircraft includes an upper-layer component and a lower-layer component which are detachably connected;
the upper-layer component includes the frame, the plurality of upper-layer propeller blades, the plurality of upper-layer power sources, the plurality of lower-layer propeller blades, the plurality of lower-layer power sources and an energy load module; the energy load module is used to supply power to the upper-layer power source and the lower-layer power source; the energy load module is connected to the upper side of the frame;
the lower-layer component includes an undercarriage and a load; and the undercarriage and the load are connected to the lower side of the frame.
In this solution, by the adoption of the above setting, the multi-rotor aircraft mainly includes the upper-layer component and the lower-layer component. On the one hand, the upper-layer component and the lower-layer component can be transported independently, so that a requirement for transportation conditions are relatively low; on the other hand, after the upper-layer component and the lower-layer component are connected together, more convenient and faster assembling of the multi-rotor aircraft can be realized, which is conductive to reducing the preparatory work before take-off and improving the fast reaction performance of the multi-rotor aircraft. In this solution, the energy load module and the frame are assembled together and arranged above the frame.
On the basis of satisfying common knowledge in the art, all the above preferred conditions can be combined randomly to obtain all the preferred examples of the present disclosure.
The present disclosure has positive progressive results:
In the multi-rotor aircraft with multi-shaft dislocation layout, the upper-layer propeller blades and the lower-layer propeller blades are staggered, so that a propeller blade pitch between the upper-layer propeller blades and the lower-layer propeller blades is relatively large; the central axis of the upper-layer power sources and the central axis of the lower-layer power sources are not collinear or do not overlap; and the upper-layer propeller blades and the lower-layer propeller blades have a relatively small overlap area in the projection direction of the frame. Compared with the multi-rotor aircraft in the prior art, the multi-rotor aircraft with multi-shaft dislocation layout can apparently reduce the flight resistance and volume under the same loading capacity, and improve the propeller efficiency. In addition, all the propeller blades of the multi-rotor aircraft are located on the same flat geometric figure in the projection direction, so that the multi-rotor aircraft can meet a higher loading requirement in the case of less affecting the volume and weight of the multi-rotor aircraft, and the multi-rotor aircraft has a relatively low requirement for transportation equipment.
The present disclosure will be further described below in a manner of embodiments, but the present disclosure is not limited to the scope of the embodiments accordingly.
The present embodiment discloses a multi-rotor aircraft with multi-shaft dislocation layout. As shown in
In this implementation mode, the upper-layer propeller blades 40 and the lower-layer propeller blades 50 are staggered, so that a propeller blade pitch between the upper-layer propeller blades 40 and the lower-layer propeller blades 50 is relatively large; the central axis of the upper-layer power sources 20 and the central axis of the lower-layer power sources 30 are not collinear or do not overlap; and the upper-layer propeller blades 40 and the lower-layer propeller blades 50 have a relatively small overlap area in the projection direction of the frame 10. Compared with a 4-shaft 8-propeller coaxial multi-rotor aircraft in the prior art, the multi-rotor aircraft with multi-shaft dislocation layout is that the upper-layer propeller blades 40 and the lower-layer propeller blades 50 have a relatively large vertical height difference and generate a relatively low mutual disturbance, and the propeller efficiency is higher; and a correspondingly required propeller rotation speed is lower, and the noise is lower. Compared with an 8-shaft 8-propeller multi-rotor aircraft in the prior art, the multi-rotor aircraft with multi-shaft dislocation layout is that the overall size is greatly reduced, and the weight, the volume and the flight resistance of the fuselage are also obviously reduced. Compared with the multi-rotor aircraft in the prior art, the multi-rotor aircraft with multi-shaft dislocation layout can apparently reduce the flight resistance and volume under the same loading capacity, and improve the propeller efficiency.
In addition, the centers of the upper-layer propeller blades 40 and the centers of the lower-layer propeller blades 50 are located on the flat geometric figure along the projection direction of the frame 10. That is, a lateral length of the multi-rotor aircraft is greater than a longitudinal length. In case of a high loading requirement, the multi-rotor aircraft does not need to be enlarged proportionally, but the number of shafts can be increased from the center of the frame 10 to a corresponding narrower section in the flat geometric figure. For example, an 8-shaft multi-rotor aircraft is changed into a 10-shaft or 12-shaft multi-rotor aircraft to meet the loading requirement, which has less influence on the volume and weight of the multi-rotor aircraft. In addition, the centers of the upper-layer propeller blades 40 and the centers of the lower-layer propeller blades 50 are located on the flat geometric figure, so that the multi-rotor aircraft has a relatively low requirement for transportation equipment, and is convenient to transport.
In summary, compared with the multi-rotor aircraft in the prior art, the present disclosure is that on the one hand, under the same loading capacity, the flight resistance and volume of the multi-rotor aircraft with multi-shaft dislocation layout are obviously reduced, and the propeller efficiency is improved; on the other hand, the multi-rotor aircraft with multi-shaft dislocation layout can meet a higher loading requirement in the case of less influence on the volume and weight of the multi-rotor aircraft, and the multi-rotor aircraft has a relatively low requirement for transportation equipment.
In this implementation mode, the above-mentioned geometric figure is an axisymmetric figure. In such setting, the multi-rotor aircraft is convenient to manufacture and assemble. Specifically, in this implementation mode, the centers of the plurality of upper-layer propeller blades 40 and the centers of the plurality of lower-layer propeller blades 50 are located on the same rectangle along the projection direction of the frame.
In other replaceable implementation modes, the centers of the plurality of upper-layer propeller blades 40 and the centers of the plurality of lower-layer propeller blades 50 may also be located on other flat geometric figures, such as the same ellipse.
In this implementation mode, an overlap area between any adjacent upper-layer propeller blade 40 and lower-layer propeller blade 50 is equal to an overlap area between another adjacent upper-layer propeller blade 40 and lower-layer propeller blade 50 along the projection direction of the frame 10.
For any two groups of adjacent upper-layer propeller blades 40 and lower-layer propeller blades 50, the overlap areas of the upper-layer propeller blades 40 and the lower-layer propeller blades 50 are equal, so that a lift generated by each propeller blade (the upper-layer propeller blade 40 or the lower-layer propeller blade 50) in a lift system of the multi-rotor aircraft is the same, which is conductive to guaranteeing the performance of the multi-rotor aircraft. That is, the multi-rotor aircraft can meet a higher loading requirement on the basis of guaranteeing the performance and in the case of less influence on the volume and weight of the multi-rotor aircraft.
As mentioned above, on the basis that the centers of the upper-layer propeller blades 40 and the centers of the lower-layer propeller blades 50 are located on the same flat geometric figure, if the overlap areas of the upper-layer propeller blades 40 and the lower-layer propeller blades 50 are equal, a plurality of included angles encircled between the plurality of upper-layer propeller blades 40 and the plurality of lower-layer propeller blades 50 (included angles are encircled between the adjacent upper-layer propeller blades and lower-layer propeller blades) are not completely the same along the projection direction of the frame 10, that is, the plurality of upper-layer propeller blades 40 and the plurality of lower-layer propeller blades 50 are disposed at unequal intervals.
It should be noted that in this implementation mode, the upper-layer power sources 20 and the lower-layer power sources 30 are motors. In other replaceable implementation modes, other types of power sources can also be used according to an actual need.
In addition, in this implementation mode, as shown in
Referring to
Continuing to refer to
As shown in
The corresponding connecting arms 102 are no longer of a cantilever structure due to the arrangement of the reinforcing arms 103, but the reinforcing arms and the adjacent connecting arms 102 can encircle a structure similar to a triangle to facilitate improving the rigidity of the fuselage and reducing vibration generated by deformation of the aircraft.
Specifically, in this implementation mode, all the accommodating regions formed between the plurality of connecting arms 102 are provided with the reinforcing arms 103. All the connecting arms 102 are no longer of the cantilever structure under the action of the reinforcing arms 103, which is conductive to significantly improving the rigidity of the fuselage, so that the vibration generated by the deformation of the aircraft can be significantly reduced.
In this implementation mode, the connecting arms 102, the reinforcing arms 103 and the frame center portion 101 are integrated. In such setting, connecting structures are eliminated, so that a relatively tedious connecting process is eliminated, and it is conductive to reducing the overall weight of the aircraft and then reducing the flight resistance of the aircraft.
It should be noted that in other replaceable implementation modes, the connecting arms 102 may also be detachably connected or fixedly connected to the reinforcing arms 103 and the frame center portion 101 to form an integrated structure. In such setting, fast assembling of the aircraft is convenient to realize.
Continuing to refer to
In this implementation mode, the multi-motor aircraft includes an upper-layer component and a lower-layer component which are detachably connected. The upper-layer component includes the frame 10, the plurality of upper-layer propeller blades 40, the plurality of upper-layer power sources 20, the plurality of lower-layer propeller blades 50 and the plurality of lower-layer power sources 30. The lower-layer component includes an undercarriage (not shown) and an operating load unit which are connected to each other; the operating load unit includes a load (not shown) and an energy load module (not shown); the energy load module is used to supply power to the upper-layer power sources 20 and the lower-layer power sources 30; the load and the undercarriage are connected to the energy load module; and the energy load module is detachably connected to the lower side of the frame 10.
What is specifically the load is determined according to the use of the multi-rotor aircraft. The load may be a fire extinguishing bomb or may be other materials such as pesticide. The energy load module may be a battery.
By the adoption of the above setting, the multi-rotor aircraft mainly includes the upper-layer component and the lower-layer component. On the one hand, the upper-layer component and the lower-layer component can be transported independently, so that a requirement for transportation conditions are relatively low; on the other hand, after the upper-layer component and the lower-layer component are connected together, more convenient and faster assembling of the multi-rotor aircraft can be realized, which is conductive to reducing the preparatory work before take-off and improving the fast reaction performance of the multi-rotor aircraft. The energy load module and the undercarriage are assembled together and arranged below the frame 10.
Those used to connect the plurality of upper-layer propeller blades 40 from among the plurality of connecting arms 102 are first connecting arms, and those used to connect the plurality of lower-layer propeller blades 50 from among the plurality of connecting arms 102 are second connecting arms. An edge of the energy load module extends to the plurality of first connecting arms and are detachably connected to the plurality of first connecting arms. If the energy load module is relatively large in size, when it needs to extend to a position corresponding to the connecting arms 102, the energy load module is connected to the connecting arms 102, and the connection is relatively convenient and reliable. In addition, compared with connection of the energy load module to the second connecting arms, the connection of the energy load module to the first connecting arms is conductive to avoiding interference between the energy load module and the lower-layer propeller blades 50, conductive to protecting the lower-layer propeller blades 50, and then conductive to improving the reliability of the multi-rotor aircraft.
In other replaceable implementation modes, the energy load module may also be assembled together with the frame 10, and is arranged above the frame 10. At this time, the multi-motor aircraft includes an upper-layer component and a lower-layer component which are detachably connected. The upper-layer component includes the frame 10, the plurality of upper-layer propeller blades 40, the plurality of upper-layer power sources 20, the plurality of lower-layer propeller blades 50, the plurality of lower-layer power sources 30 and an energy load module; the energy load module is used to supply power to the upper-layer power sources 20 and the lower-layer power sources 30; and the energy load module is connected to the upper side of the frame 10. The lower-layer component includes an undercarriage and a load; and the undercarriage and the load are connected to the lower side of the frame 10.
In the multi-rotor aircraft with multi-shaft dislocation layout, the upper-layer propeller blades 40 and the lower-layer propeller blades 50 are staggered, so that a propeller blade pitch between the upper-layer propeller blades 40 and the lower-layer propeller blades 50 is relatively large; the central axis of the upper-layer power sources 20 and the central axis of the lower-layer power sources 30 are not collinear or do not overlap; and the upper-layer propeller blades 40 and the lower-layer propeller blades 50 have a relatively small overlap area in the projection direction of the frame 10. Compared with a 4-shaft 8-propeller coaxial multi-rotor aircraft in the prior art, the multi-rotor aircraft with multi-shaft dislocation layout is that the upper-layer propeller blades 40 and the lower-layer propeller blades 50 have a relatively large vertical height difference and generate a relatively low mutual disturbance, and the propeller efficiency is higher; and a correspondingly required propeller rotation speed is lower, and the noise is lower. Compared with an 8-shaft 8-propeller multi-rotor aircraft in the prior art, the multi-rotor aircraft with multi-shaft dislocation layout is that the overall size is greatly reduced, and the weight, the volume and the flight resistance of the fuselage are also obviously reduced.
In addition, compared with 4-shaft 8-propeller and 8-shaft 8-propeller multi-rotor aircrafts, the multi-rotor aircraft with multi-shaft dislocation layout is that the frame 10 is no longer of a cantilever structure, so that the rigidity of the fuselage can also be improved, and the vibration generated by the deformation of the aircraft can be reduced. Compared with the multi-rotor aircraft in the prior art, the multi-rotor aircraft with multi-shaft dislocation layout can apparently reduce the flight resistance and volume under the same loading capacity, and improve the propeller efficiency and the rigidity of the fuselage.
In addition, as mentioned above, along the projection direction of the frame 10, the centers of the plurality of upper-layer propeller blades 40 and the centers of the plurality of lower-layer propeller blades 50 are located on the same rectangle, and the overlap area between any adjacent upper-layer propeller blade 40 and lower-layer propeller blade 50 is equal to an overlap area between another adjacent upper-layer propeller blade 40 and lower-layer propeller blade 50, so that the multi-rotor aircraft can meet a higher loading requirement on the basis of guaranteeing the performance and in the case of less influence on the volume and weight of the multi-rotor aircraft; and the multi-rotor aircraft has a relatively low requirement for transportation equipment.
The structure of the multi-rotor aircraft with multi-shaft dislocation layout in the present embodiment is basically the same as the structure of the multi-rotor aircraft with multi-shaft dislocation layout in Embodiment 1, but mainly differs in the number of propeller blades and the number of power sources. The identical numerals in the present embodiment and Embodiment 1 refer to the same elements.
As shown in
Although the specific implementation modes of the present disclosure have been described above, those skilled in the art should understand that this is only an example, and the protection scope of the present disclosure is defined by the appended claims. Those skilled in the art can make various changes or modifications to these implementations without departing from the principle and essence of the present disclosure, but these changes and modifications shall all fall within the protection scope of the present disclosure.
Number | Date | Country | Kind |
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201911307445.3 | Dec 2019 | CN | national |
This application claims priority to, and is a Continuation-In-Part of, U.S. patent application Ser. No. 16/838,048, filed on Apr. 2, 2020, now pending, which claims priority to China patent application No. 201911307445.3, filed on Dec. 18, 2019, both of which are hereby incorporated by reference in their entireties. Although incorporated by reference in their entireties, no arguments or disclaimers made in the parent application apply to this application. Any disclaimer that may have occurred during the prosecution of the above-referenced application(s) is hereby expressly rescinded.
Number | Date | Country | |
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Parent | 16838048 | Apr 2020 | US |
Child | 17209264 | US |