Patent Publication Number: US-2023150350-A1

Title: Mobile transport system

Description:
FIELD OF THE INVENTION 
     The present invention relates to a mobile transport system for transporting objects, e.g., in a technical system, for example, including a vehicle frame, a pair of first support wheels and a pair of second support wheels rotatably supported, a first drive wheel rotatable about a first drive axis, a second drive wheel rotatable about a second drive axis, and a swing frame pivotable about a swing axis relative to the vehicle frame. 
     BACKGROUND INFORMATION 
     In technical systems, for example, in production plants, mobile transport systems, e.g., autonomously driving mobile transport systems, are used for transporting objects such as small parts or crates. The mobile transport systems bring components, among other things, from logistics areas, such as a material warehouse, to workstations where the components are processed. Generic mobile transport systems are able to overcome slight pitches or slopes and small ground sills or similar obstacles. 
     A mobile transport system is described in German Patent Document No. 10 2017 201 108 and is implemented as an industrial truck, including a first support wheel at a front end, a second support wheel at a rear end, and a drive wheel disposed between the support wheels. The first support wheel is disposed on a driving frame, while the second support wheel and the drive wheel are disposed on a swing frame. The swing frame is thereby hinged on the driving frame by a horizontal swing axis. German Patent Document No. 10 2012 025 152 describes an automated guided transport system including steering rollers and a drive unit disposed on a supporting part. The drive unit includes a wheel driven by an electric motor and is displaceable relative to the supporting part by a linear actuator. 
     A vehicle is described in German Patent Document No. 10 2013 019 726 and includes a frame on which a plurality of steering units are rotatably supported. The steering units each include a drive wheel, the wheel axis thereof being rotatably supported in a wheel axle support, the wheel axle support being rotatably supported by a swing axis. 
     German Patent Document No. 10 2014 015 317 describes a vehicle having a frame on which a receiving part is guided by a linear guide. The vehicle further includes a drive unit including drive wheels rotatably supported on a swing arm by a rotary bearing. 
     A suspension for transport devices is described in PCT Patent Document No. WO 2018/136987 and includes a wheel support pivotable about a vertical axis of rotation. Two wheels rotatable about a common axis of rotation are disposed on the wheel carrier. PCT Patent Document No. WO 2019/020862 describes a vehicle including a pair of drive wheels and two pairs of support wheels. 
     Japanese Patent Document No. 2005-306178 describes an automated guided vehicle. The transport vehicle includes a pair of drive wheels and two pairs of support wheels. German Patent Document No. 10 2013 013 438 describes a transport vehicle for transporting load shelves. The transport vehicle includes a pair of drive wheels and two pairs of support wheels. German Patent Document No. 27 07 541 describes a vehicle running on rails. The vehicle includes three pairs of wheels. European Patent Document No. 2 826 693 describes a transport cart having a suspension. The suspension includes three pairs of wheels. 
     SUMMARY 
     Example embodiments of the present invention provide a mobile transport system for transporting objects. 
     According to an example embodiment of the present invention, a mobile transport system for transporting objects, e.g., in a technical system, includes a vehicle frame, a pair of first support wheels and a pair of second support wheels rotatably supported, a first drive wheel rotatable about a first drive axis extending in a transverse direction, a second drive wheel rotatable about a second drive axis extending in the transverse direction, and a swing frame pivotable about a swing axis relative to the vehicle frame. The first support wheels are disposed on the vehicle frame and the second support wheels are disposed on the swing frame. 
     A drive unit including a drive frame is disposed on the swing frame, the first drive wheel is rotatably supported on a first swing arm pivotable about a first swing axis relative to the drive frame, and the second drive wheel is rotatably supported on a second swing arm pivotable about a second swing axis relative to the drive frame. The drive frame is pivotable relative to the swing frame about a steering axis. 
     The arrangement of the mobile transport system makes it possible to compensate for uneven ground areas. Due to a pivot motion of the drive frame, the alignment of the drive wheels changes relative to the swing frame and relative to the vehicle frame. A change in the alignment of the swing frame and of the vehicle frame relative to a direction of motion of the mobile transport system can thereby be performed. The mobile transport system thereby includes rigid kinematics for preventing yielding or compliance when traveling across uneven ground areas. An installation space for further components also remains between the drive wheels. 
     The steering axis extends in a vertical direction extending perpendicular to the transverse direction. The vertical direction also extends perpendicular to the longitudinal direction. 
     According to example embodiments, the drive unit includes a swivel attached to the swing frame, the drive frame is pivotable relative to the swivel about the steering axis, and the drive unit includes an actuator motor for driving the drive unit relative the swivel. A gearbox is, for example, further provided, by which the actuator motor drives the drive frame. A change in the alignment of the swing frame and of the vehicle frame relative to a direction of motion of the mobile transport system can thereby be performed by the actuator motor. 
     According to example embodiments, the drive unit includes a rotary transmitter by which electrical energy and data can be transmitted from the drive frame to the swing frame, and from the swing frame to the drive frame. To this end, the rotary transmitter includes at least one slip ring. 
     A distance between the second support wheels and the swing axis in a base direction is, for example, at least approximately equal to a distance between the steering axis and the swing axis in the base direction. The base direction is a horizontal direction and extends perpendicular to the vertical direction. The swing axis extends in a lateral direction extending perpendicular to the vertical direction and perpendicular to the base direction. The swing axis is thus disposed at least approximately centered between the swing axis and the second support wheels in the base direction. The drive wheels thereby have approximately identical contact pressure on the ground as the second support wheels. By displacing the swing axis in the base direction, the load distribution between the drive wheels and the second support wheels can be adjusted. 
     According to example embodiments, the first swing arm and the second swing arm are coupled to each other by a coupling unit, such that a pivot motion relative to the drive frame of the first swing arm about the first swing axis in a first pivot direction brings about a pivot motion relative to the drive frame of the second swing arm about the second swing axis in a second pivot direction in a second pivot direction directed opposite the first pivot direction. The pivot motion of the swing arms about the swing axes when traveling across uneven ground areas ensures that both drive wheels always make contact with the ground and have a sufficiently high contact pressure. The use of springs is not necessary in order to achieve sufficiently high contact pressure of the drive wheels on the ground. 
     According to example embodiments, the coupling unit includes a rocker for pivoting about a coupling axis relative to the drive frame, a first strut, and a second strut, the first swing arm is connected to the rocker by the first strut, and the second swing arm is connected to the rocker by the second strut. A coupling unit having such a configuration can be produced relatively inexpensively and requires only a relatively small installation space. 
     The coupling axis extends, e.g., in a longitudinal direction extending perpendicular to the transverse direction. 
     According to example embodiments, the first drive axle and the second drive axle can be displaced relative to each other perpendicular to the transverse direction. The first drive axis and the second drive axis both extend in the transverse direction and thus are always parallel to each other. Such a displacing of the drive axes relative to each other occurs for a pivot motion of the swing arms about the swing axes. Tilting of the drive wheels for a pivot motion of the swing arms about the swing axes is, for example, prevented. For a particular alignment of the swing arms, the drive axes are aligned with each other. 
     According to example embodiments, the first swing axis extends in the transverse direction and the second swing axis extends in the transverse direction. The first swing axis and the second swing axis are, for example, aligned to each other. The swing axes thus extend parallel to each other and parallel to the drive axes. A pivot motion of the swing arms about the swing axes thus brings about a displacement of one of the drive axes toward the ground and a motion of the other drive axis away from the ground. 
     According to example embodiments, the drive unit includes a first drive motor for driving the first drive wheel and a second drive motor for driving the second drive wheel, the first drive motor is disposed on the first swing arm, and the second drive motor is disposed on the second swing arm. Gearboxes are, for example, further provided, by which the drive motors drive the drive wheels. The gearboxes are also disposed on the swing arms. The drive motors and the gearboxes are disposed in an installation space between the drive wheels for saving space. 
     The first support wheels are, for example, each supported relative to the vehicle frame rotatably about a first axis of rotation extending in a horizontal direction and relative to the vehicle frame pivotably about a first pivot axis extending in a vertical direction. The second support wheels are also, for example, each supported relative to the swing frame rotatably about a second axis of rotation extending in a horizontal direction and relative to the swing frame pivotably about a second pivot axis extending in a vertical direction. The vertical direction extends perpendicular to the transverse direction. Horizontal directions extend perpendicular to the vertical direction. Support wheels implemented in such a manner are relatively inexpensive and also facilitate the mobile transport system traveling around curves. 
     According to example embodiments, a braking device is disposed on each of the two support wheels, by which a rotation of the corresponding second support wheel about a second axis of rotation extending in the horizontal direction can be braked. The braking devices can be electromagnetically actuated, for example. The second support wheels having the braking devices also continuously make contact with the ground. Braking of the mobile transport system is thus possible at all times, approximately independently of the condition of the ground. Additional braking devices at the first support wheels and/or at the drive wheels are not necessary. 
     According to example embodiments n, the drive wheels are disposed between the first support wheels and the second support wheels in a base direction. The base direction is, as previously mentioned, a horizontal direction and extends perpendicular to the vertical direction. 
     According to example embodiments, a receiving unit is disposed on the drive frame, to which energy can be transferred inductively from a charging unit. The charging unit is implemented as a linear conductor or as a coil, for example, and is stationary and present in the ground. The energy inductively transmitted from the charging unit to the receiving unit serves, for example, for charging an electrical energy store of the mobile transport system. 
     According to example embodiments, at least one inductive sensor for detecting a magnetic field of a particularly linear conductor is disposed on the drive frame. When the magnetic field is generated by a linear conductor arranged in the ground, for example, the inductive sensor provides for following the linear conductor in order to reach a particular destination. 
     Further features and aspects of example embodiments of the present invention are explained in greater detail below with reference to the appended schematic Figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic side view of a mobile transport system. 
         FIG.  2    is a side view of a drive unit. 
         FIG.  3    is a front view of a drive unit. 
         FIG.  4    is a perspective view of a drive unit. 
         FIG.  5    is a perspective view of a drive unit. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    is a schematic side view of a mobile transport system  10 . The mobile transport system  10  is arranged for transporting objects in a technical plant. The technical plant is an industrial application, such as a production plant. The transport system  10  is also arranged, for example, for supplying goods to a residence of a private recipient in a city or in a residential region. The mobile transport system  10  is an automated guided vehicle. As illustrated, the mobile transport system  10  is present on a flat ground within a technical plant. 
     The mobile transport system  10  includes a vehicle frame  12  and a swing frame  14 . The swing frame  14  is pivotable about a swing axis  13  relative to the vehicle frame  12 . The swing axis  13  extends in the lateral direction S. The vehicle frame  12  includes an approximately rectangular cross section and extends predominantly in a base direction T and in the transverse direction S. 
     The base direction T corresponds at least approximately to the usual travel direction of the mobile transport system  10 . The lateral direction S extends perpendicular to the base direction T. The base direction T and the lateral direction S are horizontal directions and extend parallel to the flat ground on which the mobile transport system  10  is present. A vertical direction Z extends perpendicular on the flat ground and thus extends perpendicular to the base direction T and perpendicular to the lateral direction S. Each direction perpendicular to the vertical direction Z is a horizontal direction. 
     Two first support wheels  41  are disposed on the vehicle frame  12  and rotatable relative to the vehicle frame  12 . The first support wheels  41  are disposed offset to each other in the lateral direction S. Two second support wheels  42  are disposed on the swing frame  14  and rotatable relative to the swing frame  14 . The second support wheels  42  are disposed offset to each other in the lateral direction S. 
     The first support wheels  41  are each pivotable relative to the vehicle frame  12  about a first pivot axis  61  extending in a vertical direction Z. The first support wheels  41  are each further supported rotatably relative to the vehicle frame  12  about a first axis of rotation  51  extending in a horizontal direction. As illustrated, the first axes of rotation  51  extend in the lateral direction S. Depending on a pivoting of the first support wheels  41  about the first pivot axis  61 , the first axes of rotation  51  extend in the base direction T, for example, or in a different horizontal direction. The first pivot axis  61  and the first axis of rotation  51  of a first support wheel  41  do not intersect. 
     The second support wheels  42  are each pivotable relative to the swing frame  14  about a second pivot axis  62  extending in a vertical direction Z. The second support wheels  42  are each further supported rotatably relative to the swing frame  14  about a second axis of rotation  52  extending in a horizontal direction. As illustrated, the second axes of rotation  52  extend in the lateral direction S. Depending on a pivoting of the second support wheels  42  about the second pivot axis  62 , the second axes of rotation  52  extend in the base direction T, for example, or in a different horizontal direction. The second pivot axis  62  and the second axis of rotation  52  of a second support wheel  42  do not intersect. 
     The mobile transport system  10  includes a drive unit  70  disposed on the swing frame  14 . The drive unit  70  includes a drive frame  75  and a swivel  88 . The drive frame  75  is pivotable relative to the swivel  88  about a steering axis  95 . The swivel  88  is attached to the swing frame  14 . The drive frame  75  is thus pivotable relative to the swing frame  14  about a steering axis  95 . The drive unit  70  is disposed between the first support wheels  41  and the second support wheels  42  in the base direction T. 
     The drive unit  70  includes a first drive wheel  71  and a second drive wheel  72 , both rotatably supported. As illustrated, the second drive wheel  72  is hidden. The drive wheels  71 ,  72  are disposed between the first support wheels  41  and the second support wheels  42  in the base direction T. A distance between the second support wheels  42  and the swing axis  13  in a base direction T is at least approximately equal to a distance between the steering axis  95  and the swing axis  13  in the base direction T. The distance between the second support wheels  42  and the swing axis  13  in the base direction T thereby corresponds to the distance between the second pivot axes  62  and the swing axis  13  in the base direction T. 
       FIG.  2    is a side view of the drive unit  70 . The drive unit  70  includes a first swing arm  81  pivotable relative to the drive frame  75  about a first swing axis  91  and the second swing arm  82  pivotable relative to the drive frame  75  about a second swing axis  92 . The first swing axis  91  and the second swing axis  92  extend in a transverse direction Y and are aligned to each other. The swing arms  81 ,  82  are each pivotable relative to the drive frame  75  in a first pivot direction A and in a second pivot direction B aligned opposite the first pivot direction A about the swing axes  91 ,  92 . 
     The transverse direction Y extends perpendicular to the vertical direction Z. A longitudinal direction X extends perpendicular to the vertical direction Z and perpendicular to the transverse direction Y. The longitudinal direction X and the transverse direction Y are horizontal directions. Each direction perpendicular to the vertical direction Z is a horizontal direction. As previously mentioned, the drive frame  75  of the drive unit  70  is pivotable relative to the swivel  88  and to the swing frame  14  of the mobile transport system  10  about the steering axis  95 . Depending on a pivot motion of the drive frame  75  about the steering axis  95 , an alignment of the drive frame  75  changes relative to the vehicle frame  12  and relative to the swing frame  14 . As illustrated in  FIG.  1   , the longitudinal direction X corresponds to the base direction T, and the transverse direction Y corresponds to the lateral direction S. 
     The first drive wheel  71  is rotatably supported on the first swing arm  81  about a first drive axis  73  extending in the transverse direction Y. The second drive wheel  72  is rotatably supported on the second swing arm  82  about a second drive axis  74  extending in the transverse direction Y. As illustrated, the second drive wheel  72  is hidden. The drive axes  73 ,  74  thus extend parallel to the swing axes  91 ,  92  but are offset parallel relative to the same. Due to pivot motions of the swing arms  81 ,  82  about the swing axes  91 ,  92 , the drive axes  73 ,  74  are displaceable relative to each other perpendicular to the transverse direction Y. 
     The drive unit  70  includes a receiving unit  20  disposed on the drive frame  75  and to which energy can be transmitted inductively from a charging unit. The charging unit is implemented as a linear conductor or as a coil, for example. The energy inductively transmitted from the charging unit to the receiving unit  20  provides, for example, for charging an electrical energy store of the mobile transport system  10 . 
     The drive unit  70  further includes an inductive sensor  21  disposed on the drive frame  75 . The inductive sensor  21  provides for detecting a magnetic field. When the magnetic field is generated by a linear conductor arranged in the ground, for example, the inductive sensor  21  provides for following the linear conductor in order to reach a particular destination. 
       FIG.  3    is a front view of a drive unit  70 . The drive unit  70  includes a coupling unit including a rocker  80  for pivoting about a coupling axis  90  relative to the drive frame  75 , a first strut  85 , and a second strut  86 . The first swing arm  81  is connected to the rocker  80  by the first strut  85 . The second swing arm  82  is connected to the rocker  80  by the second strut  86 . The coupling axis  90  extends in the longitudinal direction X. The first swing arm  81  and the second swing arm  82  are thus coupled to each other by the coupling unit. 
     When the first drive wheel  71  travels into a ground protrusion, for example, the first drive wheel  71  is thereby displaced upward in the vertical direction Z. The first swing arm  81  is thereby pivoted about the first swing axis  91  in the first pivot direction A. The first swing arm  81  thereby brings about a pivot motion of the rocker  80  about the coupling axis  90  by the first strut  85 . The rocker  80  thereby brings about a pivot motion of the second swing arm  82  about the second swing axis  92  in the second pivot direction B by the second strut  86 . The second drive wheel  72  is thereby displaced downward in the vertical direction Z. 
     For the described procedure, the drive wheels  71 ,  72  are not displaced exclusively in the vertical direction Z, but also slightly in the longitudinal direction X. Due to the geometric arrangement of the swing arms  81 ,  82  and the swing axes  91 ,  92 , the motion of the drive wheels  71 ,  72  in the longitudinal direction is, however, negligible in comparison with the motion in the vertical direction Z. 
     The first swing arm  81  and the second swing arm  82  are thus coupled to each other by the coupling unit, such that a pivot motion of the first swing arm  81  about the first swing axis  91  in the first pivot direction A brings about a pivot motion of the second swing arm  82  about the second swing axis  92  in the second pivot direction B. The first swing arm  81  and the second swing arm  82  are also coupled to each other by the coupling unit, such that a motion of the first drive wheel  71  upward in the vertical direction Z brings about a motion of the second drive wheel  72  downward in the vertical direction Z, and vice versa. 
     The first strut  85  and the second strut  86  extent at least approximately in the vertical direction Z. The first strut  85  and the second strut  86  are each adjustable in length independently of each other. This means that an extent of the struts  85 ,  86  in the vertical direction Z is adjustable. 
     The drive unit  70  includes a tilt sensor for sensing a tilt of the rocker  80  relative to the drive frame  75  about the coupling axis  90 . The drive unit  70  includes a tilt sensor for sensing a tilt of the first swing arm  81  relative to the drive frame  75  about the first swing axis  91 . The drive unit  70  includes a tilt sensor for sensing a tilt of the second swing arm  82  relative to the drive frame  75  about the second swing axis  92 . 
       FIG.  4    is a perspective view of a drive unit  70 . The drive unit  70  includes an actuator motor for driving the drive frame  75  relative to the swivel  88  about the steering axis  95 . The actuator motor  89  is disposed in a stationary manner on the drive frame  75  and operationally connected to a gearbox, by which the actuator motor  89  drives the drive frame  75  relative to the swivel  88 . 
     The gearbox includes a pinion  97  disposed on the drive frame  75  in a stationary manner and a crown gear  98 . The crown gear  98  is disposed on the swivel  88  in a stationary manner. The pinion  97  meshes with the crown gear  98 . As illustrated, the pinion  97  and the crown gear  98  are covered by a cover panel  77  disposed on the drive frame  75  in a stationary manner. 
       FIG.  5    is a perspective view of a drive unit  70 . The drive unit  70  illustrated in  FIG.  5    substantially corresponds to the drive unit  70  illustrated in  FIG.  4   . The following primarily addresses the differences between the drive units  70 . 
     In the illustration of the drive unit  70 , the cover panel  77  is removed. The pinion  97  of the gearbox and the crown gear  98  of the gearbox are thus visible. The actuator motor  89  drives the pinion  97 , and the pinion meshes with the crown gear  98 . 
     The drive unit  70  includes a rotary transmitter  94  including an approximately rotationally symmetrical, e.g., cylindrical, base body. A cylinder axis of the base body of the rotary transmitter  94  extends in the vertical direction Z and is aligned with the steering axis  95 . 
     The rotary transmitter  94  is disposed on the drive frame  75  and is pivotable relative to the crown gear  88  about the steering axis  95 . It is also possible that the rotary transmitter  94  is disposed on the crown gear  88  in a stationary manner and is pivotable relative to the drive frame  75  about the steering axis  95 . 
     The rotary transmitter  94  includes slip rings by which electrical energy and data can be transmitted from the drive frame  75  to the crown gear  88  and to the swing frame  14 . Electrical energy and data can also be transmitted from the crown gear  88  and from the swing frame  14  to the drive frame  75  by the slip rings. 
     The drive unit  70  includes a support panel  78  disposed on the drive frame  75  in a stationary manner. The support panel  78  is thereby implemented approximately rotationally symmetrically about the steering axis  95  and encloses the drive frame  75  nearly concentrically. 
     LIST OF REFERENCE CHARACTERS 
       10  Mobile transport system 
       12  Vehicle frame 
       13  Swing axis 
       14  Swing frame 
       20  Receiving unit 
       21  First inductive sensor 
       41  First support wheel 
       42  Second support wheel 
       51  First axis of rotation 
       52  Second axis of rotation 
       61  First pivot axis 
       62  Second pivot axis 
       70  Drive unit 
       71  First drive wheel 
       72  Second drive wheel 
       73  First drive axis 
       74  Second drive axis 
       75  Drive frame 
       77  Cover panel 
       78  Support panel 
       80  Rocker 
       81  First swing arm 
       82  Second swing arm 
       85  First strut 
       86  Second strut 
       88  Swivel 
       89  Actuator motor 
       90  Coupling axis 
       91  First swing axis 
       92  Second swing axis 
       94  Rotary transmitter 
       95  Steering axis 
       97  Pinion 
       98  Crown gear 
     A First pivot direction 
     B Second pivot direction 
     S Lateral direction 
     T Base direction 
     X Length direction 
     Y Transverse direction 
     Z Vertical direction