Movable motor and cover for turntable of a mobile drive unit

Abstract

Mobile drive unit (10), comprising: A cover (20) of the mobile drive unit (10) with a first cutout section (30) and a second cutout section (32); a horizontally oriented rotary table (50) mounted in the mobile drive unit (10), wherein the rotary table (50) is designed to rotate relative to the cover (20) of the mobile drive unit (10) and is designed to move vertically through the first cutout section (30) of the cover (20) of the mobile drive unit (10); a motor (80) for rotating the turntable (50); a motor cover (40) in which the motor (80) is accommodated, wherein the motor cover (40) is designed to move vertically with the horizontally oriented turntable (50) through the second cutout section (32) in the cover (20) of the mobile drive unit (10).

Description

[0001] This application claims priority to U.S. patent application Ser. No. 15 / 934,845, filed March 23, 2018, the entire disclosure of which is hereby incorporated by reference into this application. STATE OF THE ART

[0002] The present invention relates to robot devices and, more particularly, to a mobile drive unit having a turntable.

[0003] Modern warehouses move products on a large scale. In some cases, such as certain types of fulfillment centers, the products are housed in containers ("pods"), which are four-sided shelving units on metal frames and legs. The containers are moved by mobile drive units into fulfillment centers.

[0004] Mobile drive units are robotic devices that may include, for example, center drive wheels, front and rear rollers, an upward-facing camera, a downward-facing camera, and a lifting unit for raising and lowering the container before and after movement, all enclosed within a housing. The top of the housing contains a circular opening through which a lifting device, such as a turntable, extends. The turntable engages the bottom, while the turntable is connected to the lifting unit. The turntable is also connected to a turntable motor so that, when the container is on the turntable, the turntable rotates the container to orient the front of the container as desired.

[0005] Some mobile drive units have a ring gear connected to the turntable. The ring gear has internal teeth, a pinion gear within the gear, and a turntable motor to drive the pinion gear. The layout of these mobile drive units is such that all turntable drive components, including the pinion gear and turntable motor, are located below the perimeter of the turntable—that is, the turntable pinion gear and turntable motor lie within the footprint (a cylindrical protrusion defined by the perimeter) of the turntable. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a mobile drive unit illustrating a turntable and a motor cover in the down or retracted position; Fig. 2 is a perspective view of the mobile drive unit of Fig. 1, which shows the turntable and the motor cover in an up or extended position; Fig. 3 is a plan view of the mobile drive unit of Fig. 1 from above, with parts removed to illustrate aspects of the turntable and motor assembly; and Fig. 4 is a side view of the mobile drive unit of Fig. 3. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0006] In some configurations of mobile drive units, the turntable, pinion, and turntable motor share common supports so that the turntable, motor, and pinion move up and down together within the turntable footprint under the action of the turntable lifting motor. With this in mind, it is an object of the present invention to at least partially overcome the problems known from the prior art. This configuration (i.e., the turntable drive components are located within the turntable footprint and can be moved up and down with the turntable) allows the drive components to remain engaged as the turntable is raised and lowered. This configuration offers the advantage of safely stowing moving parts beneath the turntable so that only the turntable itself protrudes from the main housing to engage a receptacle.However, the inventors of the present invention understood a layout in which the turntable drive components located within the turntable footprint have certain inherent design limitations.

[0007] In particular, the area beneath the turntable motor must contain an otherwise unobstructed space for the components in the down or retracted position to locate the turntable drive components within the turntable footprint. The most suitable location is within the turntable bearing, typically located near the periphery of the turntable. Regardless of the selection and configuration of the prior art drive components (e.g., a brushless DC motor with a pinion gear connected to its output shaft, the pinion gear driving a ring gear located either inside or outside the pinion gear), the turntable drive components of the mobile drive units known to the inventors were located within the turntable footprint.

[0008] Referring to the figures, to illustrate an example of a present embodiment, a mobile drive unit 10 is of the type configured to move containers or similar structures, such as those well known to those familiar with order fulfillment or modern warehouse automation. Accordingly, the description herein is not intended to be an all-inclusive explanation of a mobile drive unit, as those familiar with the technology in the field will understand the systems for moving and controlling the mobile drive unit.

[0009] The mobile drive unit 10 includes a cover 20 and a horizontally oriented turntable 50 mounted within the mobile drive unit 10. The turntable 50 rotates relative to the cover 20 of the mobile drive unit 10 and extends through the cover 20 of the mobile drive unit 10. A motor 80 for rotating the turntable 50 is located outside the footprint of the turntable 50. The motor 80 is housed in a motor cover 40. The motor cover 40 is located in a cutout in the cover 20 of the mobile drive unit 10, and the cover 40 moves up and down relative to the cover 20.

[0010] The turntable 50, the motor 80, and the motor cover 40 are raised and lowered together relative to the cover 20 of the mobile drive unit 10. By mounting the motor 80 and the motor cover 40 on the side of the turntable 50 rather than under the turntable 50, a space 99 under the turntable 50 can be used to accommodate other drive components, allowing for efficient stowage of components within the drive unit 10 since the cameras and other electronics are preferably centrally located. A distance G between the bottom of the motor 80 and the chassis 12 reflects the minimum dimension while the turntable 50 is in the retracted position.

[0011] The mobile drive unit 10 includes a chassis 12, a pair of wheels 14 on opposite sides of the unit 10, and a cover 20. The housing may have any configuration connected to the cover 20. The cover 20 includes side walls 22 that wrap around the perimeter of the unit 10 and a top plate 24 that seamlessly transitions from the side walls 22. A first cutout 30 is located approximately in the center of the cover 20 and has a circular shape.

[0012] The cover 20 also has a second cutout 32 in the top plate 24 that opens or merges into the first cutout 30. In this regard, the cutout 32 is referred to as being continuous with the first cutout 30.

[0013] An engine cover or shroud 40 is located within the cutout 32. The shroud 40, viewed from above, has a perimeter that conforms to the shape of the cutout 32 and includes a top plate 42 from which approximately vertical side walls 44 extend downward. Preferably, the shroud 20 and the engine cover 40 are made of an impact-resistant plastic.

[0014] A turntable 50 is located within the perimeter of the first cutout 30. Preferably, in the down or retracted position ( Fig. 1) an upper surface or contact surface 52 of the turntable 50 is approximately flush with the top plate 24 of the cover 20 and the top plate 42 of the motor cover 40 so that the upper portion of the mobile drive unit 10 has no projection extending upward.

[0015] The turntable 50 is movable vertically upwards relative to the retracted position into an up or extended position. As best described in Fig. 2, the turntable 50 has a side surface 54 extending downwardly from the contact surface 52 and extending around the periphery thereof. In the extended position, the turntable 50 is positioned to engage an underside of a container (not shown in the figures) or other structure for supporting or carrying objects. The mobile power unit 10 includes a lifting mechanism for moving the turntable 50 between the retracted and extended positions. The lifting mechanism may be of any type as understood by persons familiar with mobile power unit technology.

[0016] The mobile drive unit 10 includes features that allow the turntable 50 to rotate about a vertical axis to rotate a container when the turntable 50 engages and lifts the container. In this regard, the unit 10 includes a motor 80, which, in the embodiment of the figures, is mounted vertically such that the output shaft of the motor 80 extends vertically upward. For example, the motor 80 may be a brushless DC motor powered by batteries onboard the mobile drive unit 10.

[0017] A circular or ring gear 60 is attached to the underside of the turntable 50. The gear 60 contains teeth 62 (schematically shown in Fig.4) on the outside. A pinion gear 70 is mounted on the output shaft of the motor 80 and includes pinion teeth 72 that mesh with the teeth 62 of the ring gear 60. Thus, the pinion gear 70 and the output shaft of the motor 80 are located on the outside of the gear 60, which is generally outside the turntable bearing. Thus, the motor 80 is outside the footprint of the turntable 50 (i.e., a vertical cylindrical projection defined by the circumference of the turntable). The gear teeth 62 may be a spur gear configuration or another type of tooth.

[0018] In operation, a mobile drive unit 10 can be moved into an operating position beneath a container according to a control system while the turntable 50 of the mobile drive unit 10 is in the down or retracted position. After confirmation of proper positioning, for example, by an upward-facing camera (not shown), a lifting motor lifts the turntable 50, wheel 60, pinion 70, and motor 80 together to engage the contact surface 52 of the turntable 50 with the underside of the container.

[0019] In the extended position, the side walls 54 of the turntable 50 extend beyond the cover top plate 24, thus forming a housing that prevents a gap between the contact surface 52 of the turntable 50 and the circular edge forming the cutout 30. Also in the extended position, the side walls 44 of the motor cover 40 extend beyond the cover top plate 24, thus forming a housing that forms a gap between the motor cover top plate 42 and the edge forming the cutout 32.

[0020] When the turntable 50 is in the extended position and the weight of the container rests on the turntable 50, the control system activates the motor 80 to rotate the pinion 70 to move the wheel 60 and the turntable 50 to the desired position. The motor 80 may include an encoder so that the motor position or the magnitude of the motor rotation is known.

[0021] The present invention is described using a specific structure and function. The present invention is not limited to the specific structure and function disclosed, as persons familiar with mobile drive unit technology will understand, upon reading the patent specification, that modifications to the disclosed structure and variations thereof may be made within the scope of the claims.

Claims

[1] Mobile drive unit (10), comprising: A cover (20) of the mobile drive unit (10) having a first cutout portion (30) and a second cutout portion (32); a horizontally oriented turntable (50) mounted in the mobile drive unit (10), the turntable (50) being configured for rotation relative to the cover (20) of the mobile drive unit (10) and being configured for vertical movement through the first cutout portion (30) of the cover (20) of the mobile drive unit (10); a motor (80) for rotating the turntable (50); a motor cover (40) in which the motor (80) is received, wherein the motor cover (40) is designed to move vertically with the horizontally oriented turntable (50) through the second cutout section (32) in the cover (20) of the mobile drive unit (10). [2] Mobile drive unit (10) according to claim 1, wherein the motor (80) is located outside a contact surface of the turntable (50). [3] Mobile drive unit (10) according to claim 2, wherein the first cutout (30) includes a circular upper opening through which the turntable (50) extends. [4] Mobile drive unit (10) according to claim 3, wherein the second cutout (32) is continuous with the circular upper opening. [5] The mobile drive unit (10) of claim 4, wherein the turntable (50) has an extended position in which the turntable (50) and the motor cover (40) protrude beyond the cover (20) of the mobile drive unit (10), the motor cover (40) including a top plate (42) and side plates (44) extending downwardly from the top plate (42) to enclose the motor (80) while the turntable (50) is in the extended position. [6] The mobile drive unit (10) according to claim 4, further comprising a gear and a pinion gear (60) configured to rotate the gear; wherein the gear is a ring gear (60) having external teeth (62) and the pinion gear (70) is located outside the ring gear (60); and the pinion gear (70) is mounted on an output shaft of the motor (80). [7] A turntable and cover assembly for a mobile drive unit (10), the assembly comprising: a cover (20) of the mobile drive unit (10); a horizontally oriented turntable (50) mounted in the mobile drive unit (10), the turntable (50) being configured for rotation relative to the cover (20) of the mobile drive unit (10) and being configured to extend through a first cutout portion (30) of the cover (20) of the mobile drive unit (10); a motor (80) for rotating the turntable (50); a motor cover (40) in which the motor (80) is received, wherein the motor cover (40) is arranged in a cutout formed by the cover (20) of the mobile drive unit (10) and is designed to extend through a second cutout portion (32) of the cover (20) of the mobile drive unit (10); wherein the turntable (50), the motor (80) and the motor cover (40) are designed to be raised and lowered together relative to the cover (20) of the mobile drive unit (10). [8] An assembly according to claim 7, wherein the motor (80) is located outside a support surface of the turntable (50). [9] An assembly according to claim 8, wherein the cover (20) of the mobile drive unit (10) has a circular upper opening through which the turntable (50) extends. [10] An assembly according to claim 9, wherein the cover (20) of the mobile drive unit (10) forms a cutout (32) of the motor cover (40) which is continuous with the circular upper opening of the cover (20). [11] The assembly of claim 10, wherein the turntable (50) has an extended position in which the turntable (50) and the motor cover (40) protrude beyond the cover (20) of the mobile drive unit (10), the motor cover (40) including a top plate (42) and side plates (44) extending downwardly from the top plate (42) to enclose the motor (80) while the turntable (50) is in the extended position. [12] The assembly of claim 7, wherein the turntable (50), the motor (80) and the motor cover (40) are structurally connected. [13] A method for operating a mobile drive unit (10) according to any one of claims 1 to 6, the method comprising the steps of: (a) positioning the mobile drive unit (10) under a container while the turntable (50) of the mobile drive unit (10) is in a down position; (b) raising the turntable (50), the motor (80) and the motor cover (40) so that the turntable (50) engages a bottom of the container; and (c) rotating the turntable (50) while the container is engaged with the turntable (50) to rotate the container. [14] The method of claim 13, wherein the lifting step (b) includes lifting a ring gear (60) and a pinion gear (70) outside the ring gear (60) with the motor (80) and the motor cover (40). [15] The method of claim 14, wherein the lifting step (b) includes extending the turntable (50) over the unit cover of the mobile drive unit (10).

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