JP6836419B2 - Drive wheel unit and automatic transport trolley - Google Patents

Description

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

Conventionally, an automatic transport trolley that is automatically operated by computer control on a production line or the like in a factory has been used. Japanese Patent Application Laid-Open No. 63-118610 (Reference 1) discloses an omnidirectional unmanned vehicle that can travel straight in the front-rear direction and can also travel straight in the left-right direction by changing the direction of the drive wheels by 90 degrees. ing. Japanese Patent Application Laid-Open No. 7-149243 (Reference 2) and Japanese Patent Application Laid-Open No. 8-69323 (Reference 3) also disclose a similar automatic transfer device.
Jitsukaisho 63-118610 Japanese Unexamined Patent Publication No. 7-149243 Japanese Unexamined Patent Publication No. 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 in a fixed position. I can't. Further, as shown in FIG. 1 of Document 1, the pulse encoder 20 and the electromagnetic brake 21 used for changing the direction of the drive wheels 12 are arranged above the wheels 16 and the vehicle body frame 11. There is a risk that the omnidirectional unmanned vehicle will become larger in the vertical direction.

In the automatic transfer device of Document 2, the direction of the wheels 5 can be changed without driving the wheel drive motor 6 by the motor unit 1 with a built-in reduction mechanism. However, since the motor unit 1 with a built-in reduction mechanism is arranged above the wheels 5 and the transport device frame 12, the automatic transport device may become large in the vertical direction.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the size of the 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 transport carriage including a carriage body and a plurality of casters that support the carriage body from below to drive the automatic transport carriage. To do. The drive wheel unit includes a drive wheel, a drive mechanism that rotationally drives the drive wheels around a drive shaft that faces in the horizontal direction, and a steering mechanism that changes the direction of the drive wheels around a steering shaft that faces in the vertical direction. , Equipped with. At least a part of the steering mechanism is located between the upper end and the lower end of the drive wheels in the vertical direction. With the drive wheel unit attached to the bogie body, the entire steering mechanism is located below the upper surface of the bogie body.

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

FIG. 1 is a plan view of the automatic transport carriage according to the first embodiment. FIG. 2 is a side view showing a part of the automatic transport carriage. FIG. 3 is a plan view of the automatic transport carriage. FIG. 4 is a side view showing a part of the automatic transport carriage. FIG. 5 is a side view showing a part of the automatic transport carriage. 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 transport carriage according to the second embodiment. FIG. 9 is a plan view of the automatic transport carriage. FIG. 10 is a side view showing a part of the automatic transport carriage.

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

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

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

The upper surface 112 of the dolly body 11 is a substantially rectangular flat surface that extends substantially horizontally. The upper surface 112 of the carriage body 11 is substantially parallel to the floor surface 91. The upper surface 112 of the dolly body 11 has substantially the same size and shape as, for example, the outer peripheral edge 110 of the dolly body 11. The carriage body 11 can have various shapes and structures as long as it has a substantially flat upper surface 112 on which an object to be transported can be placed. For example, the bogie 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 dolly body 11 is the upper surface of the top plate.

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

In the automatic transport carriage 1 illustrated in FIG. 1, the number of the plurality of casters 12 is four. The four casters 12 are arranged in the vicinity of the four corners of the carriage body 11, which is substantially rectangular in a plan view. That is, the four casters 12 form the vertices of the quadrangle. The two casters 12 adjacent to each other in the width direction are arranged at substantially the same position in the front-rear direction. Each caster 12 is arranged below the carriage body 11.

The number of casters 12 may be changed as appropriate as long as it is 3 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, of the plurality of casters 12 attached to the carriage body 11, any three casters 12 form the vertices of the triangle. In other words, the plurality of casters 12 include two casters 12 arranged on a straight line and one or more casters 12 arranged at positions separated from the straight line.

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

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

The drive wheel unit 3 is attached to the carriage body 11 to drive the automatic transport carriage 1. In the example shown in FIG. 1, the automatic transport carriage 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, for example, the bogie body 11. When the bogie body 11 includes a frame, a cover portion, and a top plate as described above, the drive wheel unit 3 is preferably located below the upper end of the frame.

In the following description, when distinguishing between the two drive wheel units 3, 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. 1 is referred to as a "first drive wheel unit 3". It 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 transport carriage 1, the shortest distance between each caster 12 and the outer peripheral edge 110 of the carriage body 11 is the shortest distance between the drive wheels 33 of the first drive wheel unit 3 and the outer peripheral edge 110 of the carriage body 11. Smaller than Further, the shortest distance between each caster 12 and the outer peripheral edge 110 of the bogie main 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 bogie main body 11. The shortest distance between the caster 12 and the outer peripheral edge 110 is the distance between the central axis of the driven wheel support portion 122 of the caster 12 and the closest of the front edge, the trailing edge, and the side edges on both sides of the outer peripheral edge 110. Is the shortest distance. The shortest distance between the drive wheels 33 of the drive wheel unit 3 and the outer peripheral edge 110 is the steering shaft J2 described later of the drive wheel unit 3 and the front edge, the trailing edge, and the side edges on both sides of the outer peripheral edge 110. The shortest distance to the closest one. The positional relationship between each drive wheel unit 3, each caster 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 disk-shaped wheel that rotates about a drive shaft J1 that faces in a substantially horizontal direction. The drive shaft J1 is a virtual shaft that is the center of rotation of the substantially disk-shaped drive wheel 33 in the circumferential direction. The drive mechanism 34 is connected to the drive wheels 33 and rotationally drives the drive wheels 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 wheels 33 is located on the motor shaft, which is the rotation shaft of the electric motor. When the drive wheels 33 in the state shown in FIG. 1 are driven by the drive mechanism 34, the automatic transport carriage 1 moves in the front-rear direction.

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

In the drive wheel unit 3, the direction of the drive wheels 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 transport carriage 1 moves in the width direction. In other words, the automatic transport trolley 1 is rampant. In FIG. 3, the driven wheels 121 of each caster 12 are also drawn in the width direction. Actually, the trailing wheel 121 faces the width direction following the movement of the automatic transport carriage 1 by the drive wheel 33 in the width direction.

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

In FIG. 1, a straight line connecting the steering shaft J2 of the first drive wheel unit 3 located on the right side in the drawing and the steering shaft J2 of the second drive wheel unit 3 located on the left side in the figure in a plan view. L1 is indicated by a two-point 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 a plan view. Specifically, the straight line L1 is inclined by 45 degrees with respect to the front-rear direction. The straight line L1 is also inclined by 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 in the front-rear direction or the width direction.

In the automatic transport carriage 1, in the width direction of the carriage body 11, the steering of the first drive wheel unit 3 is performed between the outer peripheral edge 110 of the carriage body 11 and the steering motor 361 described later of the first drive wheel unit 3. Axis J2 is arranged. In other words, the distance in the width direction between the side edge of the outer peripheral edge 110 of the trolley body 11 closer to the steering motor 361 of the first drive wheel unit 3 and the steering motor 361 is the side edge. It is larger than 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 bogie main body 11, the steering shaft J2 of the second drive wheel unit 3 is arranged between the outer peripheral edge 110 of the bogie 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 of the outer peripheral edge 110 of the trolley body 11 closer to the steering motor 361 of the second drive wheel unit 3 and the steering motor 361 is the side edge. It is larger than the distance in the width direction between and the steering shaft J2 of the second drive wheel unit 3. In each drive wheel unit 3, the positional relationship between 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 swivel portion 37, and a bearing mechanism 38. The steering motor 361 is fixed to the bogie 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 rotatably supports the swivel portion 37 with respect to the carriage body 11 about the steering shaft 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 of at least a part thereof is lower than the height from the floor surface 91 to the upper end of the drive wheels 33. Further, in a state where the drive wheel unit 3 is attached to the bogie main body 11, the entire steering mechanism 36 is located below the upper surface 112 of the bogie main body 11. For example, when the bogie body 11 includes the frame, the cover portion, and the top plate as described above, the entire steering mechanism 36 is located below the upper surface 112 of the top plate. Further, it is preferable that the entire steering mechanism 36 is located 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 extending direction of the rotating shaft 362. In other words, the length of the steering motor 361 in the direction of the rotating shaft 362 is larger than the width of the steering motor 361 in the direction perpendicular to the rotating shaft 362. Preferably, at least a portion of the steering motor 361 is located between the upper and lower ends of the drive wheels 33 in the vertical direction. More preferably, the entire steering motor 361 is located between the upper and lower ends of the drive wheels 33 in the vertical direction.

The swivel portion 37 includes a swivel body 371 and a speed reduction mechanism 372. Preferably, at least a portion of the swivel portion 37 is located between the upper and lower ends of the drive wheels 33 in the vertical direction. The swivel body 371 supports the drive wheels 33 and the drive mechanism 34. The swivel body 371 is indirectly connected to the rotation shaft 362 of the steering motor 361 via the reduction mechanism 372. When the steering motor 361 is driven, the 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 around the steering shaft J2 together with the drive wheels 33 and the drive mechanism 34, so that the direction of the drive wheels 33 is changed. The turning body 371 may be directly connected to the rotating shaft 362 of the steering motor 361 and rotated by the steering motor 361 without going through the reduction mechanism 372.

The swivel body 371 includes a swivel base 373, an arm support 31, an arm 32, and an elastic member 35. The swivel base 373 is a substantially annular member centered on the steering shaft J2. In the example shown in FIG. 1, the swivel base portion 373 is a member having a substantially annular plate shape. The swivel base 373 is arranged around the upper end of the drive wheels 33.

A gear portion 374 having a substantially arc shape centered on the steering shaft J2 is provided on the outer peripheral portion of the swivel base portion 373. The gear portion 374 is provided over about 90 degrees in the circumferential direction centered on the steering shaft J2. The gear portion 374 meshes with the gear portion 375 fixed to the rotating shaft 362 of the steering motor 361. The gear portion 374 and the gear portion 375 form a worm gear which 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 deceleration mechanism 372 is a worm deceleration mechanism. The gear portion 374 of the speed reduction mechanism 372 may be provided over, for example, about 180 degrees in the circumferential direction centered on the steering shaft J2. Further, the deceleration mechanism 372 is not limited to the worm deceleration mechanism, and may be a deceleration mechanism having another structure.

The swivel base 373 is rotatably attached to the carriage 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 load in the radial direction centered on the steering shaft J2. The thrust bearing 381 includes, for example, a plurality of cam followers 383. In the example shown in FIG. 1, four cam followers 383 are arranged at substantially equal angular intervals in the circumferential direction centered on the steering shaft 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 centered on the steering shaft J2 is changed from that of FIG. The shaft 384 of each cam follower 383 is fixed to the outer peripheral portion of the swivel base portion 373 and extends radially outward around the steering shaft J2. The outer ring 385 of each cam follower 383 comes into contact with the lower surface of the bearing support portion 113 of the bogie body 11 around the swivel base portion 373.

The radial bearing 382 is, for example, a ball bearing. The radial bearing 382 is located radially inside the thrust bearing 381, for example. The radial bearing 382 is in contact with the inner peripheral surface of the swivel base 373 and the outer peripheral surface of the bearing support 113. Preferably, at least a portion of the bearing mechanism 38 is located between the upper and lower ends of the drive wheels 33 in the vertical direction.

The arm support portion 31 is a member extending downward from the swivel base portion 373. The arm support portion 31 is indirectly attached to the carriage body 11 via the swivel base portion 373. The arm 32 is a member extending in a substantially horizontal direction substantially parallel to the direction of the drive wheels 33. The arm 32 is rotatably supported by the arm support portion 31 around 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 wheels 33. For example, a sliding bearing is provided between the arm 32 and the support shaft 311. When 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 drive wheel connecting portion 321 extending upward is provided at the tip end portion of the arm 32. The drive wheel connecting portion 321 is a substantially rectangular plate-shaped portion substantially perpendicular to the floor surface 91. The drive wheels 33 are rotatably connected to the drive wheel connection portion 321 about the drive 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 arranged on the side of the drive wheel connection portion 321 opposite to the drive wheel 33. The drive mechanism 34 is also supported from below by the arm 32 via the drive wheel connecting portion 321.

A columnar guide portion 312 facing substantially in the vertical direction is provided between the drive mechanism 34 and the arm support portion 31. The guide portion 312 is, for example, a bolt. The upper end of the guide portion 312 is fixed to the arm support portion 31. The lower end 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 arranged along the guide portion 312. The elastic member 35 is, for example, a coil spring that faces in the vertical direction, and the guide portion 312 is located inside the elastic member 35 in the radial direction. The elastic member 35 elastically deforms in the vertical direction along the guide portion 312. Preferably, the entire elastic member 35 is located between the upper and lower ends of the drive wheels 33 in the vertical direction.

The upper end of the elastic member 35 comes into contact with the substantially plate-shaped elastic member support portion 313 attached to the guide portion 312. The lower end of the elastic member 35 comes into contact with 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 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 portion 313 by welding or the like, respectively.

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

As described above, in the automatic transport carriage 1, approximately the entire weight of the carriage body 11 and the object to be transported is supported by the plurality of casters 12. Therefore, the force that presses the drive wheels 33 against the floor surface 91 by the elastic member 35 may be slightly larger than the rolling resistance of the plurality of casters 12. Therefore, the power of the drive mechanism 34 can be reduced, which can contribute to energy saving of the automatic transport carriage 1. The force that presses the drive wheel 33 against the floor surface 91 by the elastic member 35 changes, for example, 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 can be adjusted by changing the distance from 32. The force that presses the drive wheels 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 transport carriage 1. In FIG. 4, the portion of the floor surface 91 in contact with the drive wheels 33 of the drive wheel unit 3 is recessed below the portion in contact with the driven wheels 121 of the casters 12. In FIG. 5, on the floor surface 91, the portion of the drive wheel unit 3 in contact with the drive wheel 33 projects upward from the portion of the caster 12 in contact with the driven wheel 121.

In the state shown in FIG. 4, from the state shown in FIG. 2, the arm 32 rotates about the support shaft 311 in the clockwise direction in the drawing, and the arm 32 moves downward. As a result, the elastic member 35 becomes slightly longer in the vertical direction. Even in the state shown in FIG. 4, the elastic member 35 is in the compressed state. Therefore, the restoring force of the elastic member 35 gives the arm 32 a moment in the clockwise direction in FIG. 4 centered on the support shaft 311 of the arm support portion 31. As a result, the drive wheels 33 are pressed against the floor surface 91.

In the state shown in FIG. 5, from the state shown in FIG. 2, the arm 32 rotates counterclockwise in the drawing about the support shaft 311 and the arm 32 moves upward. As a result, the elastic member 35 is slightly shortened in the vertical direction. Even in the state shown in FIG. 5, the elastic member 35 is in the compressed state. Therefore, the restoring force of the elastic member 35 gives the arm 32 a moment in the clockwise direction in FIG. 5 centered on the support shaft 311 of the arm support portion 31. As a result, the drive wheels 33 are pressed against the floor surface 91.

As described above, the drive wheel unit 3 is attached to the automatic transport carriage 1 including the carriage main body 11 and a plurality of casters 12 that support the carriage main body 11 from below, and drives the automatic transport 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 the drive shaft J1 facing in the horizontal direction. The steering mechanism 36 changes the direction of the drive wheels 33 around the steering shaft 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 wheels 33 in the vertical direction. When the drive wheel unit 3 is attached to the bogie main body 11, the entire steering mechanism 36 is located below the upper surface 112 of the bogie main body 11.

As a result, 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 arranged above the drive wheels. As a result, the height from the floor surface 91 to the upper surface 112 is reduced while 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 bogie main body 11. Can be done. That is, it is possible to reduce the floor of the automatic transport carriage 1.

As described above, the steering mechanism 36 includes a steering motor 361 and a turning portion 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 located between the upper end and the lower end of the drive wheels 33 in the vertical direction. As a result, the drive wheel unit 3 can be further miniaturized in the vertical direction. Preferably, the entire steering motor 361 is located between the upper and lower ends of the drive wheels 33 in the vertical direction. As a result, the drive wheel unit 3 can be further miniaturized 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. As a result, the drive wheel unit 3 can be further miniaturized 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 rotating shaft 362 facing in the horizontal direction. As a result, even when the steering motor 361 is long in the extending direction of the rotating shaft 362, it is possible to prevent the drive wheel unit 3 from becoming large in the vertical direction.

The steering mechanism 36 includes a bearing mechanism 38 in addition to the steering motor 361 and the swivel portion 37 described above. The bearing mechanism 38 supports the swivel portion 37 with respect to the carriage 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. As a result, the drive wheel unit 3 can be further miniaturized in the vertical direction. Further, since the bearing mechanism 38 is arranged around the drive wheels 33, the diameter of the bearing mechanism 38 can be made relatively large. As a result, even when the load applied to the bearing mechanism 38 is biased, the swivel portion 37 can be rotated relatively smoothly around the steering shaft J2. As a result, stable steering of the drive wheels 33 can be realized against an unbalanced load acting on the bogie body 11.

The steering mechanism 36 includes the above-mentioned steering motor 361 and a swivel portion 37, and the swivel portion 37 includes a reduction mechanism 372 that decelerates the rotation of the steering motor 361. As a result, the relatively small steering motor 361 can realize the desired rotational force and rotational speed of the turning portion 37. As a result, the drive wheel unit 3 can be miniaturized.

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. In addition, the self-locking function of the worm deceleration mechanism can suppress unintended rotation of the swivel portion 37. As a result, fluctuations in the moving direction due to the drive wheel unit 3 can be suppressed, and stable traveling of the automatic transport carriage 1 can be realized.

In the drive wheel unit 3, the steering shaft J2 is located on a straight line passing through the upper end and the lower end of the drive wheel 33. As a result, the range of movement when the drive wheels 33 rotate around the steering shaft J2 can be reduced. As a result, the drive wheels 33 can be placed close to other structures such as the casters 12.

As described above, the drive wheel unit 3 includes an arm support portion 31, an arm 32, and an elastic member 35. The arm 32 is rotatably supported around the support shaft 311 of the arm support portion 31. The elastic member 35 elastically deforms between the arm 32 and the arm support portion 31 to apply a downward force to the drive wheels 33 connected to the arm 32. When 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.

As a result, the drive wheels 33 can be suitably pressed against the floor surface 91 while the drive wheel unit 3 is downsized in the vertical direction. Therefore, the drive wheels 33 can be suitably brought into contact with the floor surface 91 regardless of the position of the floor surface 91 below the drive wheels 33 in the vertical direction. As a result, it is possible to realize suitable movement of the automatic transport carriage 1 by the drive wheel unit 3. Further, as described above, since approximately the entire weight of the bogie body 11 and the object to be transported is supported by the plurality of driven wheels 121, the distance between the bogie body 11 and the floor surface 91 is stably maintained, and the drive wheels are driven. Even when the vertical position of the 33 is changed, it is possible to prevent the vertical position of the bogie main body 11 and the inclination with respect 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. Further, the arm support portion 31 may be directly attached to the carriage main body 11. In any case, similarly to the above, 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, so that the drive wheel unit 3 is moved in the vertical direction. The drive wheels 33 can be suitably pressed against the floor surface 91 while being miniaturized. 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 that of the arm support portion 31, the arm 32, and the elastic member 35. Further, in the drive wheel unit 3, the structure of pressing the drive wheel 33 against the floor surface 91 may be omitted.

The automatic transport carriage 1 includes a carriage main 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-linear line and support the carriage body 11 from below. The first drive wheel unit 3 and the second drive wheel unit 3 are attached to the bogie main body 11. As described above, the first drive wheel unit 3 and the second drive wheel unit 3 can be miniaturized in the vertical direction. Therefore, the automatic transport carriage 1 can be miniaturized in the vertical direction.

As described above, the three or more casters 12 include four casters 12 arranged at the four corners of the carriage body 11. As a result, stable traveling of the automatic transport carriage 1 in the front-rear direction and the width direction can be realized.

In the automatic transport trolley 1, the straight line L1 connecting the steering shaft J2 of the first drive wheel unit 3 and the steering shaft J2 of the second drive wheel unit 3 in a plan view is inclined with respect to the front-rear direction and the width direction. To do. As a result, stable traveling of the automatic transport carriage 1 in the front-rear direction and the width direction can be realized. Further, the distance between the steering shaft J2 of the first drive wheel unit 3 and the steering shaft J2 of the second drive wheel unit 3 can be made relatively large. As a result, the traveling direction of the automatic transport carriage 1 can be changed with a relatively small driving force. Further, the traveling of the automatic transport carriage 1 can be made more stable.

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

In the automatic transport carriage 1, in the width direction of the carriage body 11, the steering shaft J2 of the first drive wheel unit 3 is located between the outer peripheral edge 110 of the carriage body 11 and the steering motor 361 of the first drive wheel unit 3. Is placed. As a result, the distance of the straight line L1 between the steering shafts J2 of the two drive wheel units 3 can be made relatively large. As a result, the traveling direction of the automatic transport carriage 1 can be changed with a relatively small driving force. In addition, the running of the automatic transport carriage 1 can be made more stable.

In the automatic transport carriage 1, in the width direction of the carriage body 11, the steering shaft J2 of the second drive wheel unit 3 is located between the outer peripheral edge 110 of the carriage body 11 and the steering motor 361 of the second drive wheel unit 3. Is placed. As a result, the distance of the straight line L1 between the steering shafts J2 of the two drive wheel units 3 can be further increased. As a result, the traveling direction of the automatic transport carriage 1 can be changed with a smaller driving force. In addition, the running of the automatic transport carriage 1 can be further stabilized.

As described above, the shortest distance between each caster 12 and the outer peripheral edge 110 of the bogie main body 11 is smaller than the shortest distance between the drive wheels 33 of the first drive wheel unit 3 and the outer peripheral edge 110 of the bogie main body 11. Is also small, and is smaller than the shortest distance between the drive wheels 33 of the second drive wheel unit 3 and the outer peripheral edge 110 of the bogie body 11. As a result, the load of the object to be transported, which is mainly supported by the casters 12, can be distributed over a relatively wide range on the upper surface 112 of the carriage body 11. As a result, stable running of the automatic transport carriage 1 can be realized.

The structure of the bearing mechanism 38 may be variously modified from the above. 6 and 7 are side views showing examples of other preferable bearing mechanisms 38a and 38b. The 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 radially outside the radial bearing 382.

The bearing mechanism 38b of the drive wheel unit 3b shown in FIG. 7 includes 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. The cross roller bearing 386 also serves as a thrust bearing that receives a load in the vertical direction and a radial bearing that receives a load in the radial direction centered on 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 wheels 33 in the vertical direction, similarly to the bearing mechanism 38. As a result, the drive wheel units 3a and 3b can be further miniaturized in the vertical direction in the same manner as described above. Further, since the bearing mechanisms 38a and 38b are arranged around the drive wheels 33, the diameters of the bearing mechanisms 38a and 38b can be made relatively large. As a result, even when the load applied to the bearing mechanisms 38a and 38b is biased, the swivel portion 37 can be rotated relatively smoothly around the steering shaft J2. As a result, stable steering of the drive wheels 33 can be realized against an unbalanced load acting on the bogie body 11.

The outer diameter of the bearing mechanism 38b shown in FIG. 7 is equal to or less than the outer diameter of the drive wheels 33. As a result, the drive wheel unit 3b can be miniaturized in a plan view as compared with the case where the bearing mechanism 38b projects around the drive wheel 33. 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 transport 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 transport carriage 1. FIG. 8 shows a state in which the drive wheels 33 of the drive wheel unit 3c and the trailing wheels 121 of the casters 12 are facing in the front-rear direction. FIG. 9 shows a state in which the drive wheels 33 and the trailing wheels 121 are facing in the width direction. In FIG. 10, 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 the side surface of the drive wheel unit 3c on the left side in FIG. Further, in FIG. 10, the driven wheels 121 and the driving wheel unit 3c, which overlap each other in the side view, are drawn separated 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 in place of the steering motor 361, the turning portion 37, and the bearing mechanism 38 shown in FIGS. 1 and 2. The other configuration of the drive wheel unit 3c is substantially the same as the configuration of the drive wheel unit 3 shown in FIGS. 1 and 2. In the following description, the same reference numerals are given to the configurations 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 3c is attached to the bogie main body 11, the entire steering mechanism 36c is located below the upper surface 112 of the bogie main body 11. As a result, the drive wheel unit 3c can be downsized in the vertical direction as in the drive wheel unit 3. As a result, the floor of the automatic transport carriage 1 can be lowered.

The steering motor 361c is fixed to the bogie body 11. The steering motor 361c is, for example, an electric motor. The rotation shaft 362c of the steering motor 361c faces 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 extending direction of the rotating shaft 362c. In other words, the length of the steering motor 361c in the direction of the rotating shaft 362c is smaller than the width of the steering motor 361c in the direction perpendicular to the rotating 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 wheels 33 in the vertical direction. As a result, the drive wheel unit 3c can be further miniaturized in the vertical direction. Preferably, the entire steering motor 361c is located between the upper and lower ends of the drive wheels 33 in the vertical direction. As a result, the drive wheel unit 3c can be further miniaturized in the vertical direction. Further, at least a part of the swivel portion 37c is also located between the upper end and the lower end of the drive wheel 33 in the vertical direction. As a result, the drive wheel unit 3c can be further miniaturized in the vertical direction.

In the swivel portion 37c, a substantially arc-shaped gear portion 374c centered on the steering shaft J2 is provided on the outer peripheral portion of the swivel base portion 373c. The gear portion 374c is provided over about 90 degrees in the circumferential direction centered on the steering shaft J2. The gear portion 374c meshes with the gear portion 375c fixed to the rotating shaft 362c of the steering motor 361c. The gear portion 374c and the gear portion 375c form a reduction mechanism 372c having a structure different from that of the reduction mechanism 372 shown in FIG. The reduction mechanism 372c decelerates the rotation of the steering motor 361c. As a result, the desired rotational force and rotational speed of the swivel portion 37c can be realized with the relatively small steering motor 361c. As a result, the drive wheel unit 3c can be miniaturized.

As described above, the steering motor 361c has a rotating shaft 362c that faces in the vertical direction. The rotation shaft 362c of the steering motor 361c is located at a position different from that of the steering shaft J2 in a plan view. As a result, the steering motor 361c can be arranged so as to avoid vertically above the drive wheels 33. As a result, the degree of freedom in arranging the steering motor 361c can be improved, and the drive wheel unit 3c can be further miniaturized in the vertical direction.

In the drive wheel unit 3c, the bearing mechanism 38c supports the swivel portion 37c with respect to the bogie body 11 as in the drive wheel unit 3. The bearing mechanism 38c includes, for example, a cross roller bearing 386 centered on the steering shaft J2 instead of the thrust bearing 381 and the radial bearing 382 of the bearing mechanism 38 shown in FIG. 2, similarly to 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. As a result, the drive wheel unit 3c can be further miniaturized in the vertical direction. Further, since the bearing mechanism 38c is arranged around the drive wheels 33, the diameter of the bearing mechanism 38c can be made relatively large. As a result, even when the load applied to the bearing mechanism 38c is biased, the swivel portion 37c can be rotated relatively smoothly around the steering shaft J2. As a result, stable steering of the drive wheels 33 can be realized against an unbalanced load acting on the bogie body 11. The outer diameter of the bearing mechanism 38c is equal to or less than the outer diameter of the drive wheels 33. As a result, the drive wheel unit 3c can be downsized in a plan view as compared with the case where the bearing mechanism 38c projects around the drive wheel 33.

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

For example, in the drive wheel units 3, 3a to 3c, the steering shaft J2 may be arranged at a position deviated from the straight line passing through the upper end and the lower end of the drive wheel 33. Further, the outer diameter of the bearing mechanisms 38, 38a to 38c may be larger than the outer diameter of the drive wheels 33.

In the drive wheel unit 3, if 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, the steering motor 361, the swivel portion 37, and the bearing mechanism 38 are not necessarily located. It is not necessary that at least a part of each of the above is located 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 swivel portion 37, and the bearing mechanism 38 may be entirely located above the upper end of the drive wheels 33. The same applies to the drive wheel units 3a to 3c.

The above-described embodiments and configurations in each modification may be appropriately combined as long as they do not conflict with each other.

The drive wheel unit according to the present invention can be used for various purposes. The drive wheel unit is preferably used as a drive wheel unit of an automatic transfer carriage that conveys an object to be conveyed.

1 Automatic transport trolley 3,3a to 3c Drive wheel unit 11 Car body 12 Caster 31 Arm support 32 Arm 33 Drive wheel 34 Drive mechanism 35 Elastic member 36, 36c Steering mechanism 37, 37c Swivel part 38, 38a to 38c Bearing mechanism 110 Outer peripheral edge (of the bogie body) 112 Top surface (of the bogie body) 311 Support shaft 361, 361c Steering motor 362,362c Rotating shaft (of the steering motor) 372,372c Deceleration mechanism J1 Drive shaft J2 Steering shaft L1 (Connecting the steering shafts) ) Straight

Claims (17)

A drive wheel unit that is attached to an automatic transport carriage including a carriage body and a plurality of casters that support the carriage body from below to drive the automatic transport carriage.
With the drive wheels
A drive mechanism that rotationally drives the drive wheels around a drive shaft that faces in the horizontal direction,
It is equipped with a steering mechanism that changes the direction of the drive wheels around a steering shaft that faces in the vertical direction.
At least a part of the steering mechanism is located between the upper end and the lower end of the drive wheels in the vertical direction.
When attached to the bogie body, the entire steering mechanism is located below the upper surface of the bogie body .
The steering mechanism
Arm support and
An arm that is rotatably supported around the support shaft of the arm support portion and
An elastic member that elastically deforms between the arm and the arm support portion is provided.
The drive mechanism is supported by the arm and
The elastic member applies a downward force to the drive wheels connected to the arm.
The support shaft of the arm support portion is located between the upper end and the lower end of the drive wheel in the vertical direction.
The elastic member is arranged between the drive mechanism and the support shaft in the front-rear direction.
Drive wheel unit. The steering mechanism
Steering motor and
A swivel portion that converts the rotation of the steering motor into a force that changes the direction of the drive wheels is provided.
The drive wheel unit according to claim 1, wherein at least a part of the steering motor is located between the upper end and the lower end of the drive wheels in the vertical direction. The drive wheel unit according to claim 2, wherein the entire steering motor is located between the upper end and the lower end of the drive wheels 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 the upper end and the lower end of the drive wheel in the vertical direction. The steering mechanism
A steering motor with a horizontal axis of rotation,
The drive wheel unit according to any one of claims 1 to 4, further comprising a swivel portion that converts the rotation of the steering motor into a force that changes the direction of the drive wheels. The steering mechanism
A steering motor with a rotating shaft that faces up and down,
A swivel portion that converts the rotation of the steering motor into a force that changes the direction of the drive wheels is provided.
The drive wheel unit according to any one of claims 1 to 4, wherein the rotation axis of the steering motor is located at a position different from that of the steering axis in a plan view. The steering mechanism
Steering motor and
A swivel part that converts the rotation of the steering motor into a force that changes the direction of the drive wheels, and
A bearing mechanism for supporting the swivel portion with respect to the bogie body is provided.
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 the upper end and the lower end of the drive wheel in the vertical direction. The steering mechanism
Steering motor and
A swivel part that converts the rotation of the steering motor into a force that changes the direction of the drive wheels, and
A bearing mechanism for supporting the swivel portion with respect to the bogie body is provided.
The drive wheel unit according to any one of claims 1 to 7, wherein the outer diameter of the bearing mechanism is equal to or less than the outer diameter of the drive wheel. The steering mechanism
Steering motor and
A swivel portion that converts the rotation of the steering motor into a force that changes the direction of the drive wheels is provided.
The drive wheel unit according to any one of claims 1 to 8, wherein the turning portion includes a reduction mechanism for decelerating the rotation of the steering motor. The drive wheel unit according to claim 9, wherein the deceleration mechanism is a worm deceleration mechanism. The drive wheel unit according to any one of claims 1 to 10 , wherein the steering shaft is located on a straight line passing through the upper end and the lower end of the drive wheel. The dolly body and
Three or more casters that are arranged on a non-straight line and support the dolly body from below,
The first drive wheel unit according to any one of claims 1 to 11 attached to the bogie body, and the first drive wheel unit.
An automatic transport carriage comprising the second drive wheel unit according to any one of claims 1 to 11 attached to the carriage body. The automatic according to claim 12 , 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. Transport truck. 13. The thirteenth aspect of the present invention, 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 by 45 degrees with respect to the front-rear direction. Automatic transport trolley. In the width direction of the carriage body, and the outer peripheral edge of the carriage body, between the steering motor of the first drive wheel unit, a steering shaft of the first drive wheel unit is located, to claims 12 The automatic transport trolley according to any one of 14. The shortest distance between each caster and the outer peripheral edge of the bogie body is smaller than the shortest distance between the drive wheels of the first drive wheel unit and the outer peripheral edge of the bogie body, and the second The automatic transport carriage according to any one of claims 12 to 15 , which is smaller than the shortest distance between the drive wheels of the drive wheel unit and the outer peripheral edge of the carriage body. The dolly body has a rectangular shape in a plan view,
The automatic transport carriage according to any one of claims 12 to 16 , wherein the three or more casters include four casters arranged at four corners of the carriage body.

Images