JP2018140700A - Driving wheel unit and automatic carrying truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic carrying truck capable of miniaturizing a driving wheel unit in a vertical direction.SOLUTION: A driving wheel unit 3 is mounted on an automatic carrying truck 1 including a truck main body 11 and a plurality of casters 12 supporting the truck main body 11 from below so as to drive the automatic carrying truck 1. The driving wheel unit 3 includes a driving wheel 33, a driving mechanism 34 rotatably driving the driving wheel 33 around a driving shaft J1 facing the horizontal direction, and a steering mechanism 36 changing the direction of the driving wheel 33 around a steering shaft J2 facing the vertical direction. At least a part of the steering mechanism 36 is positioned between an upper end and a lower end of the driving wheel 33 in the vertical direction. The entire steering mechanism 36 is positioned below a top surface of the truck main body 11 while the driving wheel unit 3 is mounted on the truck main body 11.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a drive wheel unit and an automatic conveyance carriage.

2. Description of the Related Art Conventionally, an automatic conveyance cart that is automatically operated by computer control in a production line in a factory has been used. Japanese Utility Model Laid-Open No. 63-118610 (Reference 1) discloses an omnidirectional unmanned vehicle that can go straight in the front-rear direction and can also go straight in the left-right direction by changing the direction of the drive wheels by 90 degrees. ing. Japanese Laid-Open Patent Publication No. 7-149243 (reference 2) and Japanese Laid-Open Patent Publication No. 8-69323 (reference 3) also disclose a similar automatic transfer device.
Japanese Utility Model Publication No. 63-118610 JP 7-149243 A JP-A-8-69323

  By the way, in the omnidirectional unmanned vehicle of Document 1, since it is necessary to drive the wheels 16 by the drive motor 18 in order to change the direction of the drive wheels 12, the vehicle body frame 11 is held at a fixed position. I can't. Further, as shown in FIG. 1 of Document 1, since the pulse encoder 20 and the electromagnetic brake 21 used for changing the direction of the drive wheel 12 are arranged above the wheel 16 and the vehicle body frame 11, There is a risk that the omnidirectional unmanned vehicle will increase in size in the vertical direction.

  In the automatic conveyance device of Document 2, the direction of the wheel 5 can be changed by the motor unit 1 with a built-in speed reduction mechanism without driving the wheel driving motor 6. However, since the motor unit 1 with a built-in speed reduction mechanism is disposed above the wheels 5 and the conveying device frame 12, the automatic conveying device may be increased in size in the vertical direction.

  The present invention has been made in view of the above problems, and an object thereof is to downsize a drive wheel unit in the vertical direction.

  An exemplary drive wheel unit according to an embodiment of the present invention is attached to an automatic conveyance carriage that includes a carriage main body and a plurality of casters that support the carriage main body from below, and drives the automatic conveyance carriage. To do. The drive wheel unit includes a drive wheel, a drive mechanism that rotationally drives the drive wheel around a drive shaft that faces in a horizontal direction, and a steering mechanism that changes the direction of the drive wheel around a steering shaft that faces up and down. . At least a part of the steering mechanism is located between the upper end and the lower end of the drive wheel in the vertical direction. In a state where the drive wheel unit is attached to the cart body, the entire steering mechanism is located below the upper surface of the cart body.

  In the present invention, the drive wheel unit can be downsized in the vertical direction.

FIG. 1 is a plan view of the automatic conveyance cart according to the first embodiment. FIG. 2 is a side view showing a part of the automatic conveyance cart. FIG. 3 is a plan view of the automatic conveyance cart. FIG. 4 is a side view showing a part of the automatic conveyance cart. FIG. 5 is a side view showing a part of the automatic conveyance cart. FIG. 6 is a side view showing another example of the bearing mechanism. FIG. 7 is a side view showing another example of the bearing mechanism. FIG. 8 is a plan view of the automatic conveyance vehicle according to the second embodiment. FIG. 9 is a plan view of the automatic conveyance cart. FIG. 10 is a side view showing a part of the automatic conveyance cart.

  FIG. 1 is a plan view of an automatic conveyance carriage 1 including a drive wheel unit 3 according to a first embodiment of the present invention. FIG. 2 is a side view showing a part of the automatic conveyance cart 1. In FIG. 2, a part of the configuration of the automatic conveyance cart 1 is shown in cross section. The same applies to FIGS. 4 to 7 and FIG. 10 described later. FIG. 2 illustrates a state in which a driven wheel 121 of a caster 12 described later and a drive wheel 33 of the drive wheel unit 3 are in contact with a floor surface 91 having substantially the same height. FIG. 2 shows a side surface of the left drive wheel unit 3 in FIG. The same applies to FIGS. 4 to 7. In FIG. 2, the driven wheel 121 and the drive wheel unit 3 that overlap each other in a side view are drawn apart in the front-rear direction.

  The automatic transport cart 1 is used for transporting an object to be transported on a production line in a factory, for example. The automatic conveyance cart 1 is also called an automatic guided vehicle and is automatically operated by computer control, for example. The automatic conveyance vehicle 1 is also called AGV (Automated Guided Vehicle). In the following description, the left-right direction in FIGS. 1 and 2 is referred to as “front-rear direction”, and the up-down direction in FIG. 1 is referred to as “width direction”. The width direction is a direction perpendicular to the front-rear direction. In addition, the above-mentioned front-back direction does not necessarily correspond with the moving direction of the automatic conveyance cart 1.

  The automatic conveyance carriage 1 includes a carriage body 11, a plurality of casters 12, and a plurality of drive wheel units 3. In the example shown in FIGS. 1 and 2, the carriage body 11 is a substantially flat member in plan view. In FIG. 1, the outer peripheral edge 110 of the carriage main body 11 is drawn with a broken line, and the configuration below the upper surface 112 of the carriage main body 11 is drawn with a solid line. The same applies to FIGS. 3, 8 and 9 described later. The outer peripheral edge 110 of the carriage main body 11 is a substantially rectangular shape whose longitudinal direction is longer than the width direction.

  The upper surface 112 of the cart body 11 is a substantially rectangular plane that extends substantially horizontally. The upper surface 112 of the cart body 11 is substantially parallel to the floor surface 91. The upper surface 112 of the cart body 11 has, for example, substantially the same size and shape as the outer peripheral edge 110 of the cart body 11. The carriage main body 11 can take various shapes and structures as long as it has a substantially flat upper surface 112 on which the object to be conveyed can be placed. For example, the cart body 11 may include a frame to which the casters 12 and the drive wheel unit 3 are attached, a cover portion that covers the upper side and the periphery of the frame, and a top plate that is attached to the upper side of the cover portion. . In this case, the upper surface 112 of the cart body 11 is the upper surface of the top plate.

  The plurality of casters 12 are attached to the cart body 11 and support the cart body 11 from below. In the automatic conveyance carriage 1, the entire weight of the carriage main body 11 and the object to be conveyed is supported by a plurality of casters 12. In the automatic conveyance carriage 1, the drive wheel unit 3 hardly supports the weight of the carriage main body 11 and the object to be conveyed.

  In the automatic conveyance cart 1 illustrated in FIG. 1, the number of the plurality of casters 12 is four. The four casters 12 are respectively arranged in the vicinity of the four corners of the cart body 11 that is substantially rectangular in a plan view. That is, the four casters 12 form a quadrangular vertex. The two casters 12 adjacent in the width direction are arranged at substantially the same position in the front-rear direction. Each caster 12 is disposed below the cart body 11.

  The number of casters 12 may be appropriately changed as long as it is three or more. Further, the arrangement of the plurality of casters 12 may be changed as appropriate. The three or more casters 12 are arranged on a non-linear line. In other words, any three casters 12 out of the plurality of casters 12 attached to the cart body 11 constitute a triangular apex. In other words, the plurality of casters 12 includes two casters 12 arranged on a straight line, and one or more casters 12 arranged at positions spaced from the straight line.

  The caster 12 includes a driven wheel 121 and a driven wheel support portion 122. The driven wheel 121 is supported by a driven wheel support part 122. The driven wheel support part 122 is connected to the lower surface of the cart body 11, for example. The driven wheel 121 is a substantially disc-shaped wheel that rotates around a central axis that faces in the horizontal direction. The driven wheel support portion 122 is, for example, a substantially columnar member that faces the vertical direction. The driven wheel support portion 122 rotates about a central axis that faces the vertical direction, whereby the direction of the driven wheel 121 is changed. The central axis of the driven wheel support part 122 is located at a position shifted from the central axis of the driven wheel 121 in plan view.

  The driven wheel 121 of the caster 12 rotates as the carriage main body 11 moves by the drive wheel unit 3. Specifically, the driven wheel support portion 122 of the caster 12 is rotated by the driving force acting in the traveling direction of the driving wheel 33 so that the central axis of the driven wheel 121 is substantially perpendicular to the moving direction of the carriage body 11. . Then, the driven wheel 121 rotates substantially parallel to the movement direction of the carriage main body 11 as the carriage main body 11 moves.

  The drive wheel unit 3 is attached to the carriage body 11 and drives the automatic conveyance carriage 1. In the example shown in FIG. 1, the automatic conveyance cart 1 includes two drive wheel units 3. The number of drive wheel units may be changed as appropriate. The drive wheel unit 3 is located below the cart body 11, for example. When the cart body 11 includes a frame, a cover part, and a top plate as described above, the drive wheel unit 3 is preferably positioned below the upper end of the frame.

  In the following description, when the two drive wheel units 3 are distinguished, the right drive wheel unit 3 in FIG. 1 is referred to as a “first drive wheel unit 3”, and the left drive wheel unit 3 in FIG. This is called “second drive wheel unit 3”. The first drive wheel unit 3 and the second drive wheel unit 3 have the same structure.

  In the automatic conveyance cart 1, the shortest distance between each caster 12 and the outer peripheral edge 110 of the cart main body 11 is the shortest distance between the drive wheel 33 of the first drive wheel unit 3 and the outer peripheral edge 110 of the cart main body 11. Smaller than. The shortest distance between each caster 12 and the outer peripheral edge 110 of the cart body 11 is smaller than the shortest distance between the drive wheel 33 of the second drive wheel unit 3 and the outer peripheral edge 110 of the cart body 11. The shortest distance between the caster 12 and the outer peripheral edge 110 is between the center axis of the driven wheel support portion 122 of the caster 12 and the closest of the front edge, the rear edge, and the side edges on both sides of the outer peripheral edge 110. Is the shortest distance. The shortest distance between the drive wheel 33 of the drive wheel unit 3 and the outer peripheral edge 110 is a steering shaft J2 (to be described later) of the drive wheel unit 3, the front edge, the rear edge, and the side edges on both sides of the outer peripheral edge 110. The shortest distance between the closest ones. Note that the positional relationship among the drive wheel units 3, the casters 12, and the outer peripheral edge 110 may be changed as appropriate.

  Each drive wheel unit 3 includes a drive wheel 33, a drive mechanism 34, and a steering mechanism 36. The drive wheel 33 is a substantially disc-shaped wheel that rotates about a drive shaft J1 that faces substantially in the horizontal direction. The drive shaft J <b> 1 is a virtual shaft that is the center of rotation in the circumferential direction of the substantially disc-shaped drive wheel 33. The drive mechanism 34 is connected to the drive wheel 33 and rotationally drives the drive wheel 33. The drive mechanism 34 includes, for example, an electric motor. In the example shown in FIG. 1, the drive shaft J1 of the drive wheel 33 is located on the motor shaft that is the rotation shaft of the electric motor. When the drive wheel 33 in the state shown in FIG. 1 is driven by the drive mechanism 34, the automatic conveyance carriage 1 moves in the front-rear direction.

  The steering mechanism 36 changes the direction of the drive wheels 33 around the steering axis J2 that faces substantially in the vertical direction. The direction of the drive wheel 33 means a direction perpendicular to the drive axis J1 in the horizontal direction. In other words, the direction of the drive wheel 33 means the traveling direction when the drive wheel 33 rotates about the drive shaft J1. In the state shown in FIG. 1, the drive wheel 33 faces in the front-rear direction. The steering axis J2 is a virtual axis that is the center of rotation when the direction of the drive wheels 33 is changed. The steering axis J2 is located on a straight line passing through the upper end and the lower end of the drive wheel 33, for example. The straight line faces substantially in the vertical direction. In other words, the steering axis J2 is a straight line passing through the contact point between the drive wheel 33 and the floor surface 91. Therefore, the steering shaft J2 intersects the drive shaft J1 at the center of the drive wheel 33.

  In the drive wheel unit 3, the direction of the drive wheel 33 can be changed by about 90 degrees by the steering mechanism 36 between the front-rear direction shown in FIG. 1 and the width direction shown in FIG. When the drive wheel 33 in the state shown in FIG. 3 is driven by the drive mechanism 34, the automatic conveyance carriage 1 moves in the width direction. In other words, the automatic conveyance cart 1 traverses. In FIG. 3, the driven wheel 121 of each caster 12 is also drawn in the width direction. Actually, the driven wheel 121 faces the width direction following the movement of the automatic conveyance carriage 1 in the width direction by the driving wheel 33.

  In the automatic conveyance carriage 1, the drive wheels 33 of each drive wheel unit 3 are driven in a predetermined direction inclined with respect to the front-rear direction and the width direction, and the drive wheels 33 are driven by the drive mechanism 34 to automatically The conveyance carriage 1 can also be moved obliquely with respect to the front-rear direction and the width direction. Further, for example, the automatic conveyance carriage 1 can be rotated on the spot by driving the two driving wheel units 3 in different rotation directions with the driving wheels 33 of the two driving wheel units 3 in the same direction.

  In FIG. 1, a straight line connecting the steering axis J2 of the first drive wheel unit 3 located on the right side in the figure and the steering axis J2 of the second drive wheel unit 3 located on the left side in the figure in plan view. L1 is indicated by a two-dot chain line. In the example shown in FIG. 1, the straight line L1 is inclined with respect to the front-rear direction and the width direction in plan view. Specifically, the straight line L1 is inclined 45 degrees with respect to the front-rear direction. The straight line L1 is inclined 45 degrees with respect to the width direction. The inclination angle of the straight line L1 with respect to the front-rear direction and the width direction may be changed as appropriate. The straight line L1 may be substantially parallel to the front-rear direction or the width direction.

  In the automatic conveyance carriage 1, the steering of the first drive wheel unit 3 is arranged between the outer peripheral edge 110 of the carriage body 11 and a steering motor 361 described later of the first drive wheel unit 3 in the width direction of the carriage body 11. An axis J2 is arranged. In other words, the distance in the width direction between the side edge closer to the steering motor 361 of the first drive wheel unit 3 in the outer peripheral edge 110 of the carriage body 11 and the steering motor 361 is the side edge. And the distance in the width direction between the first drive wheel unit 3 and the steering shaft J2 of the first drive wheel unit 3. Further, in the width direction of the carriage main body 11, the steering shaft J <b> 2 of the second drive wheel unit 3 is disposed between the outer peripheral edge 110 of the carriage main body 11 and the steering motor 361 of the second drive wheel unit 3. . In other words, the distance in the width direction between the side edge closer to the steering motor 361 of the second drive wheel unit 3 in the outer peripheral edge 110 of the carriage body 11 and the steering motor 361 is the side edge. And the distance in the width direction between the second drive wheel unit 3 and the steering shaft J2 of the second drive wheel unit 3. In each drive wheel unit 3, the positional relationship among the steering motor 361, the steering shaft J2, and the outer peripheral edge 110 may be changed as appropriate.

  The steering mechanism 36 includes a steering motor 361, a turning part 37, and a bearing mechanism 38. The steering motor 361 is fixed to the cart body 11. The turning unit 37 converts the rotation of the steering motor 361 into a force that changes the direction of the drive wheels 33. The bearing mechanism 38 supports the swivel portion 37 with respect to the carriage main body 11 so as to be rotatable about the steering axis J2.

  In the drive wheel unit 3, at least a part of the steering mechanism 36 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. In other words, the height of the steering mechanism 36 from the floor surface 91 is lower than the height from the floor surface 91 to the upper end of the drive wheel 33. Further, in a state where the drive wheel unit 3 is attached to the carriage main body 11, the entire steering mechanism 36 is positioned below the upper surface 112 of the carriage main body 11. For example, when the cart body 11 includes the frame, the cover part, and the top plate as described above, the entire steering mechanism 36 is located below the top surface 112 of the top plate. Further, the entire steering mechanism 36 is preferably positioned below the upper end of the frame.

  The steering motor 361 is, for example, an electric motor. In the example shown in FIG. 1, the rotation shaft 362 of the steering motor 361 faces the horizontal direction and is substantially parallel to the width direction. The steering motor 361 is long in the direction in which the rotation shaft 362 extends. In other words, the length of the steering motor 361 in the direction of the rotation shaft 362 is larger than the width of the steering motor 361 in the direction perpendicular to the rotation shaft 362. Preferably, at least a part of the steering motor 361 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. More preferably, the entire steering motor 361 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction.

  The turning unit 37 includes a turning body 371 and a speed reduction mechanism 372. Preferably, at least a part of the turning portion 37 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. The turning body 371 supports the drive wheel 33 and the drive mechanism 34. The turning body 371 is indirectly connected to the rotating shaft 362 of the steering motor 361 via the speed reduction mechanism 372. When the steering motor 361 is driven, the speed reduction mechanism 372 transmits the rotation of the rotation shaft 362 of the steering motor 361 to the turning body 371 while decelerating. Then, the turning body 371 rotates together with the drive wheel 33 and the drive mechanism 34 around the steering axis J2, so that the direction of the drive wheel 33 is changed. The turning body 371 may be directly connected to the rotating shaft 362 of the steering motor 361 and not rotated by the steering motor 361 without using the speed reduction mechanism 372.

  The turning body 371 includes a turning base 373, an arm support part 31, an arm 32, and an elastic member 35. The turning base 373 is a substantially annular member centered on the steering axis J2. In the example shown in FIG. 1, the turning base 373 is a substantially annular plate-like member. The turning base 373 is disposed around the upper end of the drive wheel 33.

  A substantially arcuate gear portion 374 centering on the steering axis J2 is provided on the outer peripheral portion of the turning base portion 373. The gear portion 374 is provided over about 90 degrees in the circumferential direction around the steering axis J2. The gear portion 374 meshes with a gear portion 375 fixed to the rotation shaft 362 of the steering motor 361. The gear portion 374 and the gear portion 375 constitute a worm gear that is a reduction mechanism 372. The gear portion 374 is a worm wheel, and the gear portion 375 is a worm. In other words, the speed reduction mechanism 372 is a worm speed reduction mechanism. The gear portion 374 of the speed reduction mechanism 372 may be provided over, for example, about 180 degrees in the circumferential direction around the steering axis J2. The speed reduction mechanism 372 is not limited to the worm speed reduction mechanism, and may be a speed reduction mechanism having another structure.

  The turning base 373 is rotatably attached to the carriage main body 11 by the bearing mechanism 38. In the example shown in FIG. 2, the bearing mechanism 38 includes a thrust bearing 381 that receives a load in the vertical direction and a radial bearing 382 that receives a radial load centered on the steering shaft J2. The thrust bearing 381 includes a plurality of cam followers 383, for example. In the example shown in FIG. 1, four cam followers 383 are arranged at substantially equal angular intervals in the circumferential direction around the steering axis J2. In FIG. 2, in order to facilitate understanding of the structure of the cam follower 383, the position of the cam follower 383 in the circumferential direction about the steering axis J2 is changed from FIG. A shaft 384 of each cam follower 383 is fixed to the outer peripheral portion of the turning base 373 and extends outward in the radial direction around the steering shaft J2. The outer ring 385 of each cam follower 383 is in contact with the lower surface of the bearing support portion 113 of the carriage main body 11 around the turning base portion 373.

  The radial bearing 382 is, for example, a ball bearing. The radial bearing 382 is located, for example, on the radially inner side with respect to the thrust bearing 381. The radial bearing 382 is in contact with the inner peripheral surface of the turning base 373 and the outer peripheral surface of the bearing support portion 113. Preferably, at least a part of the bearing mechanism 38 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction.

  The arm support portion 31 is a member that extends downward from the turning base portion 373. The arm support portion 31 is indirectly attached to the cart body 11 via the turning base portion 373. The arm 32 is a member extending in a substantially horizontal direction substantially parallel to the direction of the drive wheel 33. The arm 32 is supported by the arm support portion 31 so as to be rotatable about a support shaft 311 provided at the lower end portion of the arm support portion 31. The support shaft 311 extends substantially parallel to the drive shaft J1 of the drive wheel 33. For example, a sliding bearing is provided between the arm 32 and the support shaft 311. In a state where the drive wheel unit 3 is attached to the carriage body 11, the support shaft 311 of the arm support portion 31 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction.

  In the example shown in FIG. 2, a driving wheel connecting portion 321 that extends upward is provided at the tip of the arm 32. The drive wheel connecting portion 321 is a substantially rectangular plate-like portion that is substantially perpendicular to the floor surface 91. The driving wheel 33 is connected to the driving wheel connecting portion 321 so as to be rotatable about the driving shaft J1. In other words, the drive wheel 33 is supported from below by the arm 32 via the drive wheel connecting portion 321. A drive mechanism 34 is disposed on the opposite side of the drive wheel connecting portion 321 from the drive wheel 33. The drive mechanism 34 is also supported from below by the arm 32 via the drive wheel connecting portion 321.

  Between the drive mechanism 34 and the arm support portion 31, a columnar guide portion 312 is provided that faces substantially in the vertical direction. The guide part 312 is a bolt, for example. An upper end portion of the guide portion 312 is fixed to the arm support portion 31. A lower end portion of the guide portion 312 extends downward of the arm 32 through a through hole provided in the arm 32. The guide portion 312 and the arm 32 are not in contact with each other.

  The elastic member 35 is disposed along the guide portion 312. The elastic member 35 is, for example, a coil spring that faces in the up-down direction, and the guide portion 312 is located on the radially inner side of the elastic member 35. The elastic member 35 is elastically deformed in the vertical direction along the guide portion 312. Preferably, the entire elastic member 35 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction.

  The upper end of the elastic member 35 contacts a substantially plate-shaped elastic member support portion 313 attached to the guide portion 312. The lower end of the elastic member 35 contacts the periphery of the through hole of the arm 32. When the guide portion 312 and the elastic member support portion 313 are regarded as a part of the arm support portion 31, the elastic member 35 is elastically deformed between the arm support portion 31 and the arm 32. In other words, the elastic member 35 is elastically deformed between the carriage main body 11 and the arm 32 via the arm support portion 31. The lower end and the upper end of the elastic member 35 may be fixed to the arm 32 and the elastic member support 313 by welding or the like, respectively.

  The elastic member 35 is disposed between the elastic member support 313 and the arm 32 in a compressed state. Therefore, a moment in the clockwise direction in FIG. 2 is applied to the arm 32 around the support shaft 311 of the arm support portion 31 by the restoring force of the elastic member 35. Thereby, a downward force is applied to the drive wheel 33 connected to the arm 32. As a result, the drive wheel 33 is pressed against the floor surface 91. The force applied to the drive wheel 33 by the restoring force of the elastic member 35 does not necessarily have to be a vertically downward force, and may be a force having a downward component.

  As described above, in the automatic conveyance cart 1, approximately the entire weight of the cart body 11 and the object to be conveyed is supported by the plurality of casters 12. For this reason, the force for pressing the drive wheel 33 against the floor surface 91 by the elastic member 35 only needs to be slightly larger than the rolling resistance of the plurality of casters 12. For this reason, the motive power of the drive mechanism 34 can be made small and it can contribute to the energy-saving of the automatic conveyance trolley | bogie 1. FIG. For example, the force pressing the drive wheel 33 against the floor surface 91 by the elastic member 35 changes the vertical position of the nut attached to the guide portion 312 on the upper side of the elastic member support portion 313, and the elastic member support portion 313 and the arm It is possible to adjust by changing the interval with 32. The force pressing the driving wheel 33 against the floor surface 91 by the elastic member 35 may be adjusted by other methods.

  4 and 5 are side views showing a part of the automatic conveyance cart 1. FIG. In FIG. 4, the portion of the floor surface 91 that contacts the drive wheel 33 of the drive wheel unit 3 is recessed below the portion of the caster 12 that contacts the driven wheel 121. In FIG. 5, the portion of the floor surface 91 that contacts the drive wheel 33 of the drive wheel unit 3 protrudes above the portion of the caster 12 that contacts the driven wheel 121.

  In the state shown in FIG. 4, from the state shown in FIG. 2, the arm 32 rotates around the support shaft 311 in the clockwise direction in the figure, and the arm 32 moves downward. Thereby, the elastic member 35 becomes slightly long in the up-down direction. Even in the state shown in FIG. 4, the elastic member 35 is in a compressed state. Therefore, a moment in the clockwise direction in FIG. 4 is applied to the arm 32 around the support shaft 311 of the arm support portion 31 by the restoring force of the elastic member 35. As a result, the drive wheel 33 is pressed against the floor surface 91.

  In the state shown in FIG. 5, from the state shown in FIG. 2, the arm 32 rotates about the support shaft 311 in the counterclockwise direction in the figure, and the arm 32 moves upward. Thereby, the elastic member 35 is slightly shortened in the vertical direction. Also in the state shown in FIG. 5, the elastic member 35 is in a compressed state. Therefore, a moment in the clockwise direction in FIG. 5 is applied to the arm 32 around the support shaft 311 of the arm support portion 31 by the restoring force of the elastic member 35. As a result, the drive wheel 33 is pressed against the floor surface 91.

  As described above, the drive wheel unit 3 is attached to the automatic conveyance carriage 1 including the carriage main body 11 and the plurality of casters 12 that support the carriage main body 11 from below, and drives the automatic conveyance carriage 1. . The drive wheel unit 3 includes a drive wheel 33, a drive mechanism 34, and a steering mechanism 36. The drive mechanism 34 rotationally drives the drive wheels 33 around a drive shaft J1 that faces in the horizontal direction. The steering mechanism 36 changes the direction of the drive wheels 33 around the steering axis J2 that faces in the vertical direction. At least a part of the steering mechanism 36 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. In a state where the drive wheel unit 3 is attached to the cart body 11, the entire steering mechanism 36 is located below the upper surface 112 of the cart body 11.

  Thereby, the drive wheel unit 3 can be downsized in the vertical direction as compared with the conventional drive wheel unit in which the steering mechanism is disposed above the drive wheel. As a result, the height from the floor surface 91 to the upper surface 112 can be reduced in a state where the upper surface 112 is kept flat without providing a convex portion or a through hole for the drive wheel unit 3 on the upper surface 112 of the carriage body 11. Can do. That is, the floor of the automatic conveyance cart 1 can be reduced.

  As described above, the steering mechanism 36 includes the steering motor 361 and the turning unit 37 that converts the rotation of the steering motor 361 into a force that changes the direction of the drive wheels 33. At least a part of the steering motor 361 is positioned between the upper end and the lower end of the drive wheel 33 in the vertical direction. Thereby, the drive wheel unit 3 can be further downsized in the vertical direction. Preferably, the entire steering motor 361 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. Thereby, the drive wheel unit 3 can be further downsized in the vertical direction. Further, at least a part of the turning portion 37 is also located between the upper end and the lower end of the drive wheel 33 in the vertical direction. Thereby, the drive wheel unit 3 can be further downsized in the vertical direction.

  The steering mechanism 36 includes the steering motor 361 and the turning portion 37 described above, and the steering motor 361 has a rotation shaft 362 that faces in the horizontal direction. Thereby, even if the steering motor 361 is long in the direction in which the rotation shaft 362 extends, the drive wheel unit 3 can be prevented from being enlarged in the vertical direction.

  The steering mechanism 36 includes a bearing mechanism 38 in addition to the steering motor 361 and the turning portion 37 described above. The bearing mechanism 38 supports the turning portion 37 with respect to the carriage main body 11. At least a part of the bearing mechanism 38 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. Thereby, the drive wheel unit 3 can be further downsized in the vertical direction. Further, since the bearing mechanism 38 is disposed around the drive wheel 33, the diameter of the bearing mechanism 38 can be made relatively large. Thereby, even if the load applied to the bearing mechanism 38 is biased, the turning portion 37 can be rotated relatively smoothly around the steering shaft J2. As a result, it is possible to realize stable steering of the drive wheels 33 against the unbalanced load acting on the carriage body 11.

  The steering mechanism 36 includes the steering motor 361 and the turning unit 37 described above, and the turning unit 37 includes a speed reduction mechanism 372 that reduces the rotation of the steering motor 361. Thereby, the desired rotational force and rotational speed of the turning unit 37 can be realized with a relatively small steering motor 361. Thereby, the drive wheel unit 3 can be reduced in size.

  The speed reduction mechanism 372 is preferably a worm speed reduction mechanism. Thereby, a relatively large reduction ratio with respect to the rotation speed of the steering motor 361 can be realized by the reduction mechanism 372 having a small and simple structure. Further, the unintentional rotation of the turning portion 37 can be suppressed by the self-locking function of the worm reduction mechanism. As a result, fluctuations in the direction of movement by the drive wheel unit 3 can be suppressed, and stable traveling of the automatic conveyance cart 1 can be realized.

  In the drive wheel unit 3, the steering shaft J <b> 2 is located on a straight line passing through the upper end and the lower end of the drive wheel 33. Thereby, the moving range when the drive wheel 33 rotates around the steering axis J2 can be reduced. As a result, the drive wheels 33 can be disposed close to other structures such as the casters 12.

  As described above, the drive wheel unit 3 includes the arm support portion 31, the arm 32, and the elastic member 35. The arm 32 is supported so as to be rotatable about the support shaft 311 of the arm support portion 31. The elastic member 35 is elastically deformed between the arm 32 and the arm support portion 31 and applies a downward force to the drive wheels 33 connected to the arm 32. In a state where the drive wheel unit 3 is attached to the carriage body 11, the support shaft 311 of the arm support portion 31 is located between the upper end and the lower end of the drive wheel 33 in the vertical direction.

  Thereby, the drive wheel 33 can be suitably pressed against the floor surface 91 while downsizing the drive wheel unit 3 in the vertical direction. Therefore, the driving wheel 33 can be preferably brought into contact with the floor surface 91 regardless of the position of the floor surface 91 below the driving wheel 33 in the vertical direction. As a result, a suitable movement of the automatic conveyance cart 1 by the drive wheel unit 3 can be realized. Further, as described above, since the entire weight of the carriage main body 11 and the object to be conveyed is supported by the plurality of driven wheels 121, the distance between the carriage main body 11 and the floor surface 91 is stably maintained, and the drive wheels Even when the vertical position of 33 is changed, it is possible to prevent the vertical position of the carriage body 11 and the tilt relative to the horizontal plane from being changed.

  In the drive wheel unit 3, for example, the arm support portion 31, the arm 32, and the elastic member 35 may be provided separately from the turning portion 37 of the steering mechanism 36. Moreover, the arm support part 31 may be directly attachable to the cart body 11. In any case, similarly to the above, the support shaft 311 of the arm support portion 31 is positioned between the upper end and the lower end of the drive wheel 33 in the vertical direction, so that the drive wheel unit 3 is moved in the vertical direction. The drive wheel 33 can be suitably pressed against the floor surface 91 while downsizing. In the drive wheel unit 3, the pressing of the drive wheel 33 against the floor surface 91 may be realized by a structure different from the arm support portion 31, the arm 32, and the elastic member 35. In the drive wheel unit 3, the structure for pressing the drive wheel 33 against the floor surface 91 may be omitted.

  The automatic conveyance carriage 1 includes a carriage body 11, three or more casters 12, a first drive wheel unit 3, and a second drive wheel unit 3. The three or more casters 12 are arranged on a non-straight line and support the cart body 11 from below. The first drive wheel unit 3 and the second drive wheel unit 3 are attached to the cart body 11. As described above, the first drive wheel unit 3 and the second drive wheel unit 3 can be downsized in the vertical direction. Therefore, the automatic conveyance cart 1 can be downsized in the vertical direction.

  The three or more casters 12 include the four casters 12 respectively disposed at the four corners of the cart body 11 as described above. Thereby, the stable driving | running | working to the front-back direction and the width direction of the automatic conveyance trolley | bogie 1 is realizable.

  In the automatic conveyance vehicle 1, a straight line L1 connecting the steering axis J2 of the first drive wheel unit 3 and the steering axis J2 of the second drive wheel unit 3 in plan view is inclined with respect to the front-rear direction and the width direction. To do. Thereby, the stable driving | running | working to the front-back direction and the width direction of the automatic conveyance trolley | bogie 1 is realizable. Further, the distance between the steering axis J2 of the first drive wheel unit 3 and the steering axis J2 of the second drive wheel unit 3 can be made relatively large. As a result, the traveling direction of the automatic conveyance cart 1 can be changed with a relatively small driving force. Furthermore, the traveling of the automatic conveyance cart 1 can be further stabilized.

  Preferably, the straight line L1 is inclined 45 degrees with respect to the front-rear direction. Accordingly, the operation of the drive wheel unit 3 when the automatic conveyance carriage 1 travels in the front-rear direction and the operation of the drive wheel unit 3 when the automatic conveyance carriage 1 travels in the width direction are wholly or partially. Can be shared. As a result, the control of the drive wheel unit 3 can be simplified.

  In the automatic conveyance carriage 1, the steering shaft J <b> 2 of the first drive wheel unit 3 is disposed between the outer peripheral edge 110 of the carriage body 11 and the steering motor 361 of the first drive wheel unit 3 in the width direction of the carriage body 11. Is placed. Thereby, the distance of the straight line L1 between the steering axes J2 of the two drive wheel units 3 can be made relatively large. As a result, the traveling direction of the automatic conveyance cart 1 can be changed with a relatively small driving force. In addition, the traveling of the automatic conveyance cart 1 can be further stabilized.

  In the automatic conveyance carriage 1, the steering shaft J <b> 2 of the second drive wheel unit 3 is disposed between the outer peripheral edge 110 of the carriage body 11 and the steering motor 361 of the second drive wheel unit 3 in the width direction of the carriage body 11. Is placed. Thereby, the distance of the straight line L1 between the steering axes J2 of the two drive wheel units 3 can be further increased. As a result, the traveling direction of the automatic conveyance cart 1 can be changed with a smaller driving force. In addition, the traveling of the automatic conveyance cart 1 can be further stabilized.

  As described above, the shortest distance between each caster 12 and the outer peripheral edge 110 of the cart body 11 is more than the shortest distance between the drive wheel 33 of the first drive wheel unit 3 and the outer peripheral edge 110 of the cart body 11. And smaller than the shortest distance between the drive wheel 33 of the second drive wheel unit 3 and the outer peripheral edge 110 of the carriage main body 11. Thereby, the load of the conveyed object mainly supported by the caster 12 can be dispersed in a relatively wide range of the upper surface 112 of the carriage main body 11. As a result, stable traveling of the automatic conveyance cart 1 can be realized.

  The structure of the bearing mechanism 38 may be variously changed from the above. 6 and 7 are side views showing examples of other preferable bearing mechanisms 38a and 38b. A bearing mechanism 38a of the drive wheel unit 3a shown in FIG. 6 includes a ball bearing centered on the steering shaft J2 as a thrust bearing 381a instead of the plurality of cam followers 383 of the bearing mechanism 38 shown in FIG. The thrust bearing 381a is located on the radially outer side than the radial bearing 382.

  A bearing mechanism 38b of the drive wheel unit 3b shown in FIG. 7 includes a cross roller bearing 386 centered on the steering axis J2 instead of the thrust bearing 381 and the radial bearing 382 of the bearing mechanism 38 shown in FIG. The cross roller bearing 386 serves both as a thrust bearing that receives a load in the vertical direction and a radial bearing that receives a load in the radial direction around the steering shaft J2.

  At least a part of the bearing mechanisms 38a and 38b is located between the upper end and the lower end of the drive wheel 33 in the vertical direction, like the bearing mechanism 38. Thereby, similarly to the above, the drive wheel units 3a and 3b can be further downsized in the vertical direction. Further, since the bearing mechanisms 38a and 38b are disposed around the drive wheel 33, the diameters of the bearing mechanisms 38a and 38b can be made relatively large. Thereby, even if it is a case where the load added to bearing mechanism 38a, 38b is biased, the turning part 37 can be rotated comparatively smoothly centering | focusing on the steering axis J2. As a result, it is possible to realize stable steering of the drive wheels 33 against the unbalanced load acting on the carriage body 11.

  The outer diameter of the bearing mechanism 38 b shown in FIG. 7 is equal to or smaller than the outer diameter of the drive wheel 33. Thereby, compared with the case where the bearing mechanism 38b protrudes around the drive wheel 33, the drive wheel unit 3b can be reduced in size in plan view. The outer diameter of the bearing mechanism 38b is the diameter of the outer peripheral surface of the outer ring of the cross roller bearing 386.

  8 and 9 are plan views of the automatic conveyance carriage 1 including the drive wheel unit 3c according to the second embodiment of the present invention. FIG. 10 is a side view showing a part of the automatic conveyance cart 1. FIG. 8 shows a state in which the drive wheel 33 of the drive wheel unit 3c and the driven wheel 121 of the caster 12 face the front-rear direction. FIG. 9 shows a state in which the driving wheel 33 and the driven wheel 121 are oriented in the width direction. FIG. 10 illustrates a state in which the driven wheel 121 of the caster 12 and the drive wheel 33 of the drive wheel unit 3c are in contact with the floor surface 91 having substantially the same height. FIG. 10 shows a side surface of the left drive wheel unit 3c in FIG. In FIG. 10, the driven wheel 121 and the drive wheel unit 3 c that overlap each other in a side view are drawn apart in the front-rear direction.

  The steering mechanism 36c of the drive wheel unit 3c includes a steering motor 361c, a turning portion 37c, and a bearing mechanism 38c having different structures instead of the steering motor 361, the turning portion 37, and the bearing mechanism 38 shown in FIGS. The other structure of the drive wheel unit 3c is substantially the same as the structure of the drive wheel unit 3 shown in FIGS. In the following description, the same symbol is given to the configuration of the drive wheel unit 3c corresponding to each configuration of the drive wheel unit 3.

  In the drive wheel unit 3c, at least a part of the steering mechanism 36c is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. Further, in a state where the drive wheel unit 3 c is attached to the carriage main body 11, the entire steering mechanism 36 c is positioned below the upper surface 112 of the carriage main body 11. Thereby, similarly to the drive wheel unit 3, the drive wheel unit 3c can be downsized in the vertical direction. As a result, the floor of the automatic conveyance cart 1 can be reduced.

  The steering motor 361 c is fixed to the cart body 11. The steering motor 361c is, for example, an electric motor. A rotation shaft 362c of the steering motor 361c is directed in the vertical direction. In the example shown in FIG. 10, the rotation shaft 362c faces downward. The steering motor 361c is a flat motor that is short in the direction in which the rotating shaft 362c extends. In other words, the length of the steering motor 361c in the direction of the rotation shaft 362c is smaller than the width of the steering motor 361c in the direction perpendicular to the rotation shaft 362c. The rotation of the steering motor 361c is converted into a force for changing the direction of the drive wheels 33 by the turning portion 37c.

  At least a part of the steering motor 361c is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. Thereby, the drive wheel unit 3c can be further downsized in the vertical direction. Preferably, the entire steering motor 361c is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. Thereby, the drive wheel unit 3c can be further downsized in the vertical direction. Further, at least a part of the turning portion 37c is also positioned between the upper end and the lower end of the drive wheel 33 in the vertical direction. Thereby, the drive wheel unit 3c can be further reduced in size in the vertical direction.

  In the turning portion 37c, a substantially arcuate gear portion 374c centering on the steering axis J2 is provided on the outer peripheral portion of the turning base portion 373c. The gear portion 374c is provided over about 90 degrees in the circumferential direction around the steering axis J2. The gear portion 374c meshes with a gear portion 375c fixed to the rotating shaft 362c of the steering motor 361c. The gear portion 374c and the gear portion 375c constitute a speed reduction mechanism 372c having a structure different from that of the speed reduction mechanism 372 shown in FIG. The deceleration mechanism 372c decelerates the rotation of the steering motor 361c. Thereby, the desired rotational force and rotational speed of the turning part 37c can be realized with a relatively small steering motor 361c. Thereby, the drive wheel unit 3c can be reduced in size.

  As described above, the steering motor 361c has the rotary shaft 362c that faces in the up-down direction. The rotation shaft 362c of the steering motor 361c is located at a position different from the steering shaft J2 in plan view. Thereby, the steering motor 361c can be arranged avoiding the vertical upper side of the drive wheel 33. As a result, the degree of freedom of arrangement of the steering motor 361c can be improved, and the drive wheel unit 3c can be further downsized in the vertical direction.

  In the drive wheel unit 3 c, like the drive wheel unit 3, the bearing mechanism 38 c supports the turning portion 37 c with respect to the cart body 11. The bearing mechanism 38c includes, for example, a cross roller bearing 386 centered on the steering shaft J2 in place of the thrust bearing 381 and the radial bearing 382 of the bearing mechanism 38 shown in FIG. 2 in the same manner as the bearing mechanism 38b shown in FIG. .

  At least a part of the bearing mechanism 38c is located between the upper end and the lower end of the drive wheel 33 in the vertical direction. Thereby, the drive wheel unit 3c can be further downsized in the vertical direction. Moreover, since the bearing mechanism 38c is arrange | positioned around the drive wheel 33, the diameter of the bearing mechanism 38c can be made comparatively large. Thereby, even if the load applied to the bearing mechanism 38c is biased, the turning portion 37c can be rotated relatively smoothly around the steering shaft J2. As a result, it is possible to realize stable steering of the drive wheels 33 against the unbalanced load acting on the carriage body 11. The outer diameter of the bearing mechanism 38 c is equal to or smaller than the outer diameter of the drive wheel 33. Thereby, compared with the case where the bearing mechanism 38c protrudes around the drive wheel 33, the drive wheel unit 3c can be reduced in size in plan view.

  Various changes can be made in the drive wheel units 3, 3 a to 3 c and the automatic conveyance cart 1.

  For example, in the drive wheel units 3, 3 a to 3 c, the steering shaft J <b> 2 may be disposed at a position shifted from a straight line passing through the upper end and the lower end of the drive wheel 33. Further, the outer diameters of the bearing mechanisms 38, 38 a to 38 c may be larger than the outer diameter of the drive wheel 33.

  In the drive wheel unit 3, as long as at least a part of the steering mechanism 36 is positioned between the upper end and the lower end of the drive wheel 33 in the vertical direction, the steering motor 361, the turning portion 37, and the bearing mechanism 38 are not necessarily required. It is not necessary that at least a part of each of these is positioned between the upper end and the lower end of the drive wheel 33 in the vertical direction. For example, any one of the steering motor 361, the turning unit 37, and the bearing mechanism 38 may be positioned above the upper end of the drive wheel 33. The same applies to the drive wheel units 3a to 3c.

  The configurations in the above-described embodiments and modifications may be combined as appropriate as long as they do not contradict each other.

  The drive wheel unit according to the present invention can be used for various applications. The drive wheel unit is preferably used as a drive wheel unit of an automatic transport carriage that transports an object to be transported.

DESCRIPTION OF SYMBOLS 1 Automatic conveyance trolley 3, 3a-3c Drive wheel unit 11 Bogie main body 12 Caster 31 Arm support part 32 Arm 33 Drive wheel 34 Drive mechanism 35 Elastic member 36, 36c Steering mechanism 37, 37c Turning part 38, 38a-38c Bearing mechanism 110 Outer peripheral edge 112 of the bogie body 112 Upper surface 311 of the bogie body 361 Support shaft 361, 361c Steering motor 362, 362c Rotating shaft 372, 372c Deceleration mechanism J1 Drive shaft J2 Steering shaft L1 (Connecting the steering shafts) ) Straight line

Claims (18)

A drive wheel unit that is attached to an automatic conveyance carriage that includes a carriage main body and a plurality of casters that support the carriage main body from below, and that drives the automatic conveyance carriage,
Drive wheels,
A drive mechanism that rotationally drives the drive wheels around a drive shaft that faces in the horizontal direction;
A steering mechanism that changes the direction of the drive wheels around a steering shaft that faces in the vertical direction;
With
At least a part of the steering mechanism is located between the upper end and the lower end of the drive wheel in the vertical direction,
The whole steering mechanism is located below the upper surface of the bogie main body in a state of being attached to the bogie main body. The steering mechanism is
A steering motor;
A turning unit that converts the rotation of the steering motor into a force that changes the direction of the drive wheel;
With
The drive wheel unit according to claim 1, wherein at least a part of the steering motor is positioned between an upper end and a lower end of the drive wheel in a vertical direction.   The drive wheel unit according to claim 2, wherein the entire steering motor is positioned between an upper end and a lower end of the drive wheel in the vertical direction.   The drive wheel unit according to claim 2 or 3, wherein at least a part of the turning portion is located between an upper end and a lower end of the drive wheel in the vertical direction. The steering mechanism is
A steering motor having a rotating shaft facing in the horizontal direction;
A turning unit that converts the rotation of the steering motor into a force that changes the direction of the drive wheel;
The drive wheel unit according to any one of claims 1 to 4, further comprising: The steering mechanism is
A steering motor having a rotating shaft facing in the vertical direction;
A turning unit that converts the rotation of the steering motor into a force that changes the direction of the drive wheel;
With
5. The drive wheel unit according to claim 1, wherein the rotation shaft of the steering motor is located at a position different from the steering shaft in plan view. The steering mechanism is
A steering motor;
A turning unit that converts the rotation of the steering motor into a force that changes the direction of the drive wheel;
A bearing mechanism for supporting the swivel portion with respect to the carriage body;
With
The drive wheel unit according to any one of claims 1 to 6, wherein at least a part of the bearing mechanism is located between an upper end and a lower end of the drive wheel in a vertical direction. The steering mechanism is
A steering motor;
A turning unit that converts the rotation of the steering motor into a force that changes the direction of the drive wheel;
A bearing mechanism for supporting the swivel portion with respect to the carriage body;
With
The drive wheel unit according to any one of claims 1 to 7, wherein an outer diameter of the bearing mechanism is equal to or less than an outer diameter of the drive wheel. The steering mechanism is
A steering motor;
A turning unit that converts the rotation of the steering motor into a force that changes the direction of the drive wheel;
With
The drive wheel unit according to any one of claims 1 to 8, wherein the turning unit includes a speed reduction mechanism that reduces the rotation of the steering motor.   The drive wheel unit according to claim 9, wherein the speed reduction mechanism is a worm speed reduction mechanism. An arm support,
An arm supported rotatably about a support shaft of the arm support;
An elastic member that elastically deforms between the arm and the arm support portion and applies a downward force to the drive wheel connected to the arm;
With
11. The support shaft according to claim 1, wherein the support shaft of the arm support portion is positioned between an upper end and a lower end of the drive wheel in a vertical direction in a state where the support shaft is attached to the carriage main body. Drive wheel unit.   The drive wheel unit according to any one of claims 1 to 11, wherein the steering shaft is located on a straight line passing through an upper end and a lower end of the drive wheel. The cart body,
Three or more casters arranged on a non-linear line and supporting the cart body from below;
The first drive wheel unit according to any one of claims 1 to 12, which is attached to the bogie body;
The second drive wheel unit according to any one of claims 1 to 12, which is attached to the bogie body;
An automatic conveyance cart equipped with.   The automatic operation according to claim 13, wherein a straight line connecting the steering shaft of the first drive wheel unit and the steering shaft of the second drive wheel unit in a plan view is inclined with respect to the front-rear direction and the width direction. Conveyor cart.   The straight line connecting the steering shaft of the first drive wheel unit and the steering shaft of the second drive wheel unit in a plan view is inclined by 45 degrees with respect to the front-rear direction. Automatic transport cart.   The steering shaft of the first drive wheel unit is disposed between an outer peripheral edge of the cart body and a steering motor of the first drive wheel unit in the width direction of the carriage body. The automatic conveyance cart as described in any one of 15.   The shortest distance between each caster and the outer peripheral edge of the cart body is smaller than the shortest distance between the driving wheel of the first driving wheel unit and the outer peripheral edge of the cart body, and the second The automatic conveyance cart according to any one of claims 13 to 16, wherein the cart is smaller than a shortest distance between a driving wheel of the driving wheel unit and the outer peripheral edge of the cart body. The cart body is rectangular in plan view,
The automatic conveyance cart according to any one of claims 13 to 17, wherein the three or more casters include four casters respectively disposed at four corners of the cart body.

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