HK1061222B - Floating drive for vehicle - Google Patents

Description

Mobile drive for a vehicle

Technical Field

The present invention relates generally to material handling vehicles and, more particularly, to a vehicle having a vertically movable drive assembly.

Background

Automatic Guided Vehicles (AGVs) are widely used in the material handling industry to transport loads. The term AGV is generally used to refer to a heavy vehicle having any one of a number of known automatically controlled guidance systems. The term automatic guided vehicles (AGCs) generally refers to vehicles that are used for similar purposes but that have a relatively small application size and a relatively small payload. The structure of current AGC designs typically includes a frame with swivel casters at the four corners of the frame. Other features may include a single drive wheel assembly and a plurality of rigid caster wheels (rigid cassettes) for controlling the direction of the vehicle. In one current design, two rigid casters are fixed to the frame and positioned approximately midway between the swivel casters on the sides of the frame. The axes of the two pairs of swivel castors and the axis of the rigid castor wheel are generally parallel to each other. The steerable drive member is typically connected to the frame of the vehicle by a plate which is hinged to the frame and is spring loaded to ensure that the steerable drive wheel maintains sufficient friction with the support surface.

While such an arrangement is generally acceptable for a consistent support surface, encountering locations where the ground is not sufficiently level and flat may result in a loss of directional control of the vehicle. In particular, when the vehicle encounters an uneven surface, the swivel casters and rigid casters directly mounted to the vehicle frame may cause one or more of the three sets of wheels to disengage from the support surface. Since the rigid caster wheels are used for controlling the direction of the vehicle, the loss of contact between the rigid caster wheels and the ground can cause the direction of the vehicle to be out of control. The only wheel which is always in contact with the ground is the articulated and resiliently loaded steerable drive wheel.

Disclosure of Invention

In view of the foregoing, there is a need for an automated guided vehicle that more effectively maintains directional control of the vehicle or AGV. In particular, it is desirable to have both the steerable drive wheel and the at least one rigid castor wheel remain in contact with the ground surface at all times.

To meet these and other needs, and in accordance with the purpose of the present invention, as will be apparent to those of ordinary skill in the art based on the specification and the accompanying drawings, there is provided a material handling vehicle, comprising: a load-bearing frame having a plurality of casters for rollingly supporting the load-bearing frame on a support surface; a drive assembly including a drive frame, a drive wheel and a non-driven rigid castor wheel, the drive wheel and rigid castor wheel being arranged for movement with the drive frame; and a pivot connection assembly connecting the drive frame to the load frame and allowing vertical and angular displacement of the drive frame relative to the load frame, the pivot connection assembly being connected to the load frame at a first axis and to the drive frame at a second axis spaced from the first axis to ensure that the drive wheel and rigid castor wheel are in contact with the support surface and operate effectively even in uneven contours.

Wherein the drive assembly includes a second rigid castor wheel rotatable about only a single axis and disposed on the drive frame, the drive wheel and the rigid castor wheel being arranged to form a triangle. And, the first end of the pivot connection assembly is connected to the drive frame with a bearing block, wherein the triangle is oriented such that the point defined by the drive wheel is located in front of the bearing block.

According to another aspect of the present invention, there is provided a vehicle including: a bearing frame with bearing wheels; a driving wheel; a non-driven rigid caster wheel; and a pivot connection assembly connecting the drive wheel and the rigid castor to the carriage frame such that the drive wheel and the rigid castor are vertically movable relative to the carriage frame without change in angular orientation.

According to still another aspect of the present invention, there is provided a vehicle including: a load-bearing frame having a plurality of casters for rollingly supporting the load-bearing frame on a support surface; the driving assembly comprises a driving frame, a driving wheel and a rigid self-aligning wheel, wherein the driving wheel and the rigid self-aligning wheel are arranged on the driving frame; and a pivot connection assembly connecting the drive frame to the load frame and allowing the drive frame to move in a vertical direction and angularly displace relative to the load frame, wherein the pivot connection assembly includes a pair of pivot rods each having a first end pivotally connected to the load frame and a second end pivotally connected to the drive frame.

According to still another aspect of the present invention, there is provided a vehicle including: a carrying frame; a plurality of casters fixed to the carriage frame for rollably supporting the carriage frame on a support surface; a drive assembly including a drive frame, a drive wheel rotatable about first and second axes, and a non-driven rigid castor wheel rotatable about only a single axis, the drive wheel and rigid castor wheel being arranged for movement with the drive frame; and a pivotal connection coupling the drive assembly to the carriage frame to allow the drive frame, drive wheel and rigid castor wheel to move in a vertical and angular direction relative to the carriage frame.

Further areas of applicability of the present invention will become apparent from the detailed description, claims and drawings provided hereinafter. However, it should be understood that: the detailed description and specific examples, while disclosing preferred embodiments, are given by way of illustration only, since various modifications and improvements within the spirit and scope of the invention will become apparent to those skilled in the art.

Drawings

The present invention will become more fully understood from the detailed description, the appended claims and the accompanying drawings, wherein:

fig. 1 is a bottom perspective view of an AGC according to the present invention;

FIG. 2 is a top perspective view of the drive assembly and the moving engagement assembly shown in FIG. 1;

FIG. 3 is a perspective view of the drive assembly;

FIG. 4 is a perspective view of the pivot connection assembly;

FIG. 5 is a side perspective view of the AGC shown in FIG. 1 with one side of the carrier frame tube removed for clarity;

FIG. 6 is a horizontal elevational view of the cart shown in FIG. 5 with the drive assembly in a centered position;

FIG. 7 is a horizontal elevational view of the cart shown in FIG. 5, with the drive assembly in a fully raised position and rotated in a counterclockwise direction;

FIG. 8 is a horizontal elevational view of the cart shown in FIG. 5, with the drive assembly in a fully lowered position and rotated in a clockwise direction; and

fig. 9 is a cross-sectional view taken along line 9-9 of fig. 6.

Detailed Description

Referring to fig. 1-5, the self-steering vehicle 10 of the present invention is diagrammatically illustrated. It is noted that the vertically displaceable driving means according to the invention has many applications other than for the illustrated automatic guiding vehicle. For example, the present invention may be used with automated guided vehicles and other material handling vehicles having a variety of configurations that may allow these vehicles to work more accurately along contoured surfaces.

An automatic guided vehicle (AGC)10 includes a carrier frame 12 supported at each corner by a rotating caster wheel 14. A drive assembly 16 includes a drive frame 18, a drive wheel 20, and a pair of rigid casters 22. Both the drive wheel 20 and the rigid castor wheel 22 are fixed to the drive frame 18 and move together. As is known in the art, the drive wheel 20 is rotatable about a drive shaft 24 and a steering shaft 26. Each rigid caster wheel 22 is only rotatable about a single axis 28 perpendicular to the longitudinal axis 30 of the self-steering vehicle. Thus, when the rigid casters contact the surface supporting the cart, the cart tends to be directionally controlled in its axial direction.

The pivot connection assembly 36 connects the drive assembly 16 to the carriage frame 12 by two pivots so that the drive assembly can move vertically relative to the carriage frame. The pivot connection assembly 36 is also configured to allow the angular orientation of the drive assembly 16 relative to the load frame 12 to be varied within a predetermined range. The degrees of freedom in the vertical direction and angle allow the drive wheel unit 20 and rigid castor 22 to always be in contact with the vehicle load bearing surface even when the profile of this load bearing surface is uneven.

In the illustrated embodiment, the pivot connection assembly 36 includes first and second side bars 38 and 40 (fig. 4) connected to each other by a support plate 42. These rods are pivotally connected at one end to the carriage frame 12 by frame carriage blocks 44 and at the other end to the drive frame 18 by drive means carriage blocks 46. A first pivot 50 rotatably connects the rear ends of the rods 38 and 40 and the support plate 42 to the frame bearing block 44. In the same manner, the front ends of the levers 38 and 40 are rotatably connected with the corresponding drive device bearing blocks 46, respectively. The pivot rods 50 and 52 are preferably parallel to each other and to the rigid castor axle 28.

The pivot connection assembly 36 can have a variety of shapes and configurations, and the illustrated embodiment includes a cutout 56 in the plate 42 to receive the rigid castor wheel 22. The ability of the drive assembly to move vertically and reorient angularly, and the three-wheel configuration of the drive wheel and rigid castor wheel, allows the steerable drive wheel and at least one rigid castor wheel to remain in contact with the uneven contoured ground at all times. Therefore, the driving/direction control of the automatic guided vehicle is superior in its entirety to the design of the former vehicle. Fig. 6-8 illustrate the capability of the present invention to move vertically and reorient angularly. Specifically, fig. 6 is a horizontal side view of the cart 10 with the drive assembly 16 in a centered position, i.e., the bearing surfaces of the drive wheel 20, rigid castor 22, and rotary castor 14 are at the same elevation. The drive assembly 16 is rotatable relative to the carriage frame 12 about axes 50 and 52 to provide vertical movement and angular variation when the cart encounters uneven surfaces. For example, the drive assembly 16 is in a fully raised position and rotated counterclockwise in FIG. 7 and in a fully lowered position and rotated clockwise in FIG. 8. It is worth noting that these orientations are shown in the figures for purposes of example, and that the range of motion of the drive assembly is not necessarily limited to the specific orientations or ranges shown and described herein.

The range of vertical movement and rotational motion allowed by pivot connection assembly 36 is preferably defined by appropriately configured and positioned pivot stops. In the illustrated embodiment, the range of vertical movement is limited to 2.54 centimeters, up to and down to 1.27 centimeters above the center position shown in FIG. 6. In addition, a biasing mechanism is preferably provided between the carrier frame and the drive frame to apply a downward spring load on the tri-wheel drive assembly 16. This additional load enhances the friction of the drive wheel 20 and rigid castor wheel 22 against the support surface. Finally, one or more rotational stops may also be required to prevent over-rotation of the drive frame 18. As best seen in fig. 2, the drive wheel 20, and its associated limit switch and actuator 59, are typically disposed at the front end of the frame 18. The power source, illustrated as a pair of batteries 58, is located in the center and the rear is for housing the vehicle's control electronics. In this configuration, the load on the drive frame 18 tends to rotate the drive assembly about the shaft 52 in a counterclockwise direction as indicated by arrow 54. The rotation stop is used to limit this rotation.

Those skilled in the art will recognize that there are many pivot and rotation stop configurations, such as brackets (brackets), bolts, and the like, that can be used to limit the vertical movement and rotation of the drive assembly, and that various springs or other biasing mechanisms can be used to maintain drive friction. For example, the illustrated embodiment includes a plurality of stop assemblies 60 disposed adjacent the drive device carrier block 46 (fig. 5-9) that act as a pivot stop and biasing mechanism for the drive assembly 16. Each stop assembly 60 includes a spring bracket 62 secured to the load frame 12 and a coil spring 64 disposed about a bolt 65. The spring 64 is in compression between the bracket 62 and the pivot plate 42 to apply a downward bias to the plate. A down stop washer 66 is normally spaced a predetermined distance from the bracket 62 by a spacer tube 68. Thus, the drive assembly 16 may be pivoted downward from its center position (as in fig. 6) until the washer is offset the predetermined distance and abuts against the bracket 62 (as in fig. 8). The upward pivot stop is a stop flange 70 (fig. 5 and 9) that is secured to the drive frame 18 and includes a leg 72 that abuts the load frame 12 or carriage 62 when the drive assembly 16 is in the fully raised position (fig. 7).

Finally, in the illustrated embodiment, a spin-stop assembly 76 is disposed near the forward end of the drive assembly 16. The whirl-stop assembly (see fig. 5) includes a spin carrier 78 having a slot 80 with a stop pin 82 disposed therein for movement therein. The bracket 78 and pin 82 are secured to the drive frame 18 and the load frame 12, respectively, so that relative movement between the frames is limited by the abutting engagement of the bracket/pin. While stop assembly 60, spring 64, and stop assembly 76 have been described above, those skilled in the art will appreciate that there are many known equivalent mechanisms in the art that can provide the blocking and biasing action without departing from the scope of the invention as defined in the appended claims.

A further benefit of using this movement drive is that the carriage frame 12 and the drive frame 18 are independently carried. Thus, the payload supported by the load frame 12 and swivel castors 14 may vary depending on the objectives of the operation, but the load applied to the drive is in principle determined by the weight of the drive and the bias provided by the coil springs 62. By including the onboard power supply, controls and mechanical components necessary for automated movement, the drive assembly can also be separated from the load frame 12 and pivot connection assembly 36 if desired for use as an automated vehicle. Examples of such applications for use as automotive vehicles may include use as small towing devices or light vehicles where space constraints prevent efficient movement of a larger load-bearing frame 12.

The foregoing discussion discloses and describes one embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined in the following claims.

Claims (20)

1. A vehicle, comprising:

a load-bearing frame having a plurality of casters for rollingly supporting the load-bearing frame on a support surface;

a drive assembly including a drive frame, a drive wheel and a non-driven rigid castor wheel, the drive wheel and rigid castor wheel being arranged for movement with the drive frame; and

a pivot connection assembly connecting the drive frame to the carrier frame and allowing vertical and angular displacement of the drive frame relative to the carrier frame, the pivot connection assembly being connected to the carrier frame at a first axis and to the drive frame at a second axis spaced from the first axis.

2. The vehicle of claim 1, wherein the pivot connection assembly includes a pair of pivot rods, each pivot rod having a first end pivotally connected to the load frame and a second end pivotally connected to the drive frame.

3. The vehicle of claim 2 wherein the pivot connection assembly further comprises a plate extending between the two pivot rods, said plate being positioned below the drive frame and including a cutout, said rigid castor wheel being positioned within said cutout and moving vertically within said cutout.

4. The vehicle of claim 1 wherein said drive assembly includes a second rigid castor wheel rotatable about only a single axis and disposed on said drive frame, said drive wheel and said rigid castor wheel being arranged to form a triangle.

5. The vehicle of claim 4, wherein the first end of the pivot connection assembly is connected to the drive frame with a carrier block, and wherein the triangle is oriented such that the point defined by the drive wheel is forward of the carrier block.

6. The vehicle of claim 1, wherein the drive wheel is rotatable about a first axis to provide drive power and about a second axis to control direction.

7. The vehicle of claim 6, wherein the second axis is movable in a vertical direction relative to the load frame, and wherein the pivot connection assembly allows the drive frame to rotate relative to the load frame about the second axis.

8. The vehicle of claim 1, wherein the drive assembly further comprises a power source and a controller on the drive frame, the controller communicably coupled to the drive wheel so that the drive assembly operates as an automotive vehicle.

9. The vehicle of claim 1, further comprising a biasing mechanism that urges the drive frame downward relative to the load frame.

10. The vehicle of claim 9, wherein the biasing mechanism is a coil spring.

11. The vehicle of claim 1, further comprising a stop assembly secured to the carrier frame to limit vertical movement of the drive frame relative to the carrier frame.

12. The vehicle of claim 11, wherein the pivot connection assembly further comprises a second stop assembly for limiting rotation of the drive frame relative to the carrier frame.

13. The vehicle of claim 1 wherein the rigid caster wheel rotates about only a single axis of rotation.

14. A vehicle, comprising:

a bearing frame with bearing wheels;

a driving wheel;

a non-driven rigid caster wheel; and

a pivot connection assembly connecting the drive wheel and the rigid castor wheel to the carriage frame such that the drive wheel and the rigid castor wheel are vertically movable relative to the carriage frame without change in angular orientation.

15. The vehicle of claim 14 further comprising a drive frame, wherein said rigid castor wheel is rotatable about only a single axis, wherein said drive wheel and said rigid castor wheel are disposed on said drive frame, and wherein said pivot connection assembly couples said drive frame to said load frame and allows vertical movement of said drive frame, drive wheel, and rigid castor wheel relative to said load frame.

16. The vehicle of claim 15, wherein the pivot connection assembly connects the drive frame to the load frame and allows the drive frame to move vertically and rotate relative to the load frame.

17. The vehicle of claim 14 further comprising a drive frame, wherein the drive wheel and the rigid castor wheel are disposed on the drive frame, and wherein the pivot connection assembly is connected to the carrier frame at a first axis and to the drive frame at a second axis spaced from the first axis.

18. A vehicle, comprising:

a load-bearing frame having a plurality of casters for rollingly supporting the load-bearing frame on a support surface;

the driving assembly comprises a driving frame, a driving wheel and a rigid self-aligning wheel, wherein the driving wheel and the rigid self-aligning wheel are arranged on the driving frame; and

a pivot connection assembly connecting the drive frame to the load frame and allowing vertical and angular displacement of the drive frame relative to said load frame, wherein said pivot connection assembly comprises a pair of pivot rods each having a first end pivotally connected to the load frame and a second end pivotally connected to the drive frame.

19. The vehicle of claim 18 wherein the pivot connection assembly further comprises a plate extending between the two pivot rods, said plate being positioned below the drive frame and including a cutout, said rigid castor wheel being positioned within said cutout and moving vertically within said cutout.

20. A vehicle, comprising:

a carrying frame;

a plurality of casters fixed to the carriage frame for rollably supporting the carriage frame on a support surface;

a drive assembly including a drive frame, a drive wheel rotatable about first and second axes, and a non-driven rigid castor wheel rotatable about only a single axis, the drive wheel and rigid castor wheel being arranged for movement with the drive frame; and

a pivotal connection coupling the drive assembly to the carriage frame to allow the drive frame, drive wheel and rigid castor wheel to move in a vertical and angular direction relative to the carriage frame.