Automated guided vehicle

Abstract

This automated guided vehicle capable of traveling in the front-rear direction comprises: a vehicle body frame; right and left drive wheels that are provided apart from each other in the vehicle width direction of the vehicle body frame; a traveling drive source for driving the right and left drive wheels; a lift base part that is supported on the vehicle body frame so as to be rotatable about an axis in the vehicle width direction; a swing arm equipped with right and left branch arms that respectively have base portions fixed to the right and left ends of the lift base part, have intermediate portions extending toward either one side in the front-rear direction, and have rear-end portions connected together at a position separated from the right and left drive wheels by a given distance; a driven wheel provided at the connection portion of the right and left branch arms; and a lifting device that includes the lift base part and allows a load to be placed thereon for lifting and lowering.

Description

Automated guided vehicle

[0001] The present disclosure relates to an automated guided vehicle.

[0002] In recent years, in factories and logistics sites, automated guided vehicles that can automatically move materials without human intervention in the transportation of goods have been used. For example, Patent Document 1 discloses an automated guided vehicle in which caster wheels are provided at the four corners of the front, rear, left, and right of a cart for placing loads, and drive wheels are provided at the central part of the cart. Further, Patent Document 2 discloses an automated guided vehicle in which caster wheels are provided at the four corners of the front, rear, left, and right of a frame having a lifting mechanism for placing and lifting loads, and steerable drive wheels are provided at two locations before and after the central part of the frame.

[0003] Japanese Patent Application Laid-Open No. 7-33027 Japanese Patent Application Laid-Open No. 2011-88500

[0004] Both of the above Patent Documents 1 and 2 have a configuration in which driven wheels are provided at the four corners of the front, rear, left, and right of a cart (frame), and drive wheels are provided at the central part of the cart (frame). Therefore, when a load is placed on the cart or the lifting device, and in this case, if the load is placed in an uneven load state, when the transport vehicle is driven, an excessive weight is applied to one of the driven wheels, and there is a problem that the running becomes unstable. That is, the driven wheel with the excessive weight and the driven wheel on the diagonal line float or are in a state close to floating, and the grounding state of the driven wheel with respect to the running surface becomes insufficient, resulting in unstable running. Such a problem becomes a more serious problem in a transport vehicle equipped with a lifting device for placing a load, depending on the height of the load placed on the lifting device, causing more unstable running.

[0005] The present disclosure has been made in view of the above-described circumstances, and the problem to be solved by the present disclosure is to provide an automated guided vehicle equipped with a lifting device for placing and lifting a load, which can run stably against an uneven load of the load.

[0006] To solve the above problems, this disclosure employs the following means. Specifically, the automated guided vehicle according to this disclosure is an automated guided vehicle that can travel in the front-rear direction and comprises a vehicle frame, left and right drive wheels provided spaced apart in the vehicle width direction of the vehicle frame, a drive source for driving the left and right drive wheels, a lift base supported on the vehicle frame so as to be rotatable along the axis in the vehicle width direction, a swing arm having left and right branch arms, each having its base end fixed to the left and right ends of the lift base, with its intermediate portion extending in either the front-rear direction or the other, and its rear end connected at a position a certain distance away from the left and right drive wheels, a driven wheel provided at the connection portion of the left and right branch arms, and a lifting device including the lift base for lifting and lowering loads.

[0007] In one aspect of the present disclosure, the connecting portion is provided with a caster frame that is rotatable at the center in the vehicle width direction and has an axis extending in the front-rear direction, and a pair of driven wheels are provided at each of the outer ends in the vehicle width direction of the caster frame, which are located inward in the vehicle width direction from the left and right drive wheels.

[0008] In another aspect of the present disclosure, the left and right branch arms of the swing arm are each formed in an arch shape, rising upward from one end in the front-rear direction and then descending toward the other end, and the left and right drive sources for driving the left and right drive wheels are provided below these branch arms.

[0009] In another aspect of this disclosure, the left and right drive wheels are located outward in the width direction of the vehicle body frame.

[0010] This is a plan view showing the basic configuration of an automated guided vehicle (AGV) as one embodiment of the present disclosure. This is a cross-sectional view of the AGV taken along line A-A in Figure 1. This is a front view showing the basic configuration of the AGV. This is a plan view of the AGV taken along line B-B in Figure 3. This is a side view showing the basic configuration of the AGV.

[0011] Hereinafter, an embodiment of this disclosure will be described with reference to the attached drawings.

[0012] In Figures 1 to 4, the automated guided vehicle 1 comprises a body frame 2, left and right drive wheels 3a and 3b, driving power sources (motors) 4a and 4b, a lift base 5, a swing arm 6, left and right driven wheels 7a and 7b, and a lifting device 8.

[0013] The automated guided vehicle (AGV) 1 can travel in the direction of arrow F and the opposite direction of arrow B. For convenience, in this explanation, arrow F will be described as forward and arrow B as backward. The AGV 1 can also change its direction of travel by making the rotation speeds of its left and right drive wheels 3a and 3b different. The AGV 1's travel status and the vertical movement of the lifting device 8 are controlled by wireless commands from an external source.

[0014] As shown in Figures 1 and 4, the vehicle frame 2 has a front wall portion 21 and left and right side wall portions 22a and 22b extending rearward from the front wall portion 21. Left and right drive wheels 3a and 3b are rotatably mounted on the outside of the side wall portions 22a and 22b. Inside the side wall portions 22a and 22b, there are driving sources (motors) 4a and 4b that rotate the drive wheels 3a and 3b. The driving sources (motors) 4a and 4b are positioned close to the left and right drive wheels 3a and 3b, respectively. Left and right driven wheels 7a and 7b, configured as casters, are provided on the front wall portion 21.

[0015] An axle body 23 is rotatably supported between the center portions in the front-rear direction of the side walls 22a and 22b of the vehicle frame 2. A lift base portion 5 is provided on the axle body 23, and the lift base portion 5 is rotatable about the rotation axis X0 of the axle body 23.

[0016] As shown in Figure 2, the lift base 5 is a structure comprising a main wall portion 24 rising upward from the shaft 23 and a horizontal wall portion 25 extending rearward from the lower end of the main wall portion 24. Two guide protrusions 26, 26 are provided on the rear surface of the main wall portion 24, spaced apart to the left and right.

[0017] As shown in Figures 1 and 4, the base ends of the swing arms 6 are fixed to the left and right ends of the lift base 5. The swing arms 6 have an intermediate section that extends in either the front-rear or rear-facing direction. The swing arms 6 consist of left and right branch arms 41a and 41b, and connecting rods 42a and 42b that are provided between the rear ends of the left and right branch arms 41a and 41b. The connecting rods 42a and 42b are positioned at a certain distance apart at the rear ends of the left and right branch arms 41a and 41b, and the rectangular portion formed by the connecting rods 42a and 42b and the left and right branch arms 41a and 41b constitutes the connecting portion 43 of the left and right branch arms 41a and 41b.

[0018] As shown in Figures 1, 4, and 5, an axle body 44 is provided at the center of the connecting rods 42a and 42b in the vehicle width direction, extending between these connecting rods 42a and 42b in the longitudinal direction of the vehicle frame 2. A caster frame 45 is supported on the axle body 44 so as to be rotatable about the rotation axis X1 of the axle body 44. A pair of left and right driven wheels 46a and 46b, configured as casters, are provided at each of the outer ends of the caster frame 45 in the vehicle width direction. In this case, the left and right driven wheels 46a and 46b are located inward in the vehicle width direction from the left and right drive wheels 3a and 3b.

[0019] The swing arm 6, configured in this way, is rotatable in a vertical plane about the shaft 44 together with the lift base 5. The left and right branch arms 41a and 41b of the swing arm 6 are formed in an arch shape, rising upward from one end where a connecting rod 42a and 42b in the front-rear direction is provided, and descending toward the other end where the lift base 5 is provided. Below these branch arms 41a and 41b, left and right drive sources (motors) 4a and 4b are provided to drive the left and right drive wheels 3a and 3b, respectively.

[0020] As shown in Figure 2, the lifting device 8 includes a lift base 5 and comprises a lift lifting section 61, a screw shaft 62, and a drive mechanism 63 that rotates the screw shaft 62. The lift lifting section 61 comprises a top plate 64 on which a load is placed, a lifting plate 65 provided on the lower surface of the top plate 64 so as to extend downward, an engaging recess 66 provided on the lifting plate 65 that engages with the guide projection 26, and a female screw member 67 provided on the lifting plate 65 into which the screw shaft 62 is screwed.

[0021] The guide projection 26 and the engaging recess 66 restrict movement of the lifting plate 65 to only the vertical direction, while restricting movement in the forward, backward, left, and right directions (configured as a so-called linear guide).

[0022] As shown in Figure 2, the screw shaft 62 is provided so as to protrude upward from the horizontal wall portion 25 of the lift foundation 5. This screw shaft 62 is rotationally driven by a drive mechanism 63 provided on the horizontal wall portion 25. The drive mechanism 63 includes a motor 81, a sprocket wheel 82 provided on the rotation axis of the motor 81, a sprocket wheel 83 provided at the lower end of the screw shaft 62, and a chain 84 wound between the sprocket wheels 82 and 83.

[0023] Furthermore, the drive mechanism 63 is not limited to a combination of a sprocket wheel 83 and a chain 84 wound between sprocket wheels 82 and 83, but may also use gears, a combination of a timing belt and pulley, etc.

[0024] When the motor 81 is driven to rotate the screw shaft 62 under this configuration, the female screw member 67 moves up and down, causing the lifting plate 65 and the top plate 64 to move up and down. At this time, the lifting section 61 is only able to move up and down because the engaging recess 66 is guided by the guide projection 26.

[0025] In the above configuration, the optimal load ratio for achieving stable running on these wheels is determined by the dimensional ratio of the distance L1 from the left and right drive wheels 3a and 3b to the rotation axis X0 of the shaft 23, the distance L2 from the left and right driven wheels 7a and 7b to the rotation axis X0 of the shaft 23, and the distance L3 from the left and right driven wheels 46a and 46b to the rotation axis X0 of the shaft 23. This load ratio is set to a state in which stable running is possible under no load conditions.

[0026] Furthermore, in the above configuration, the screw shaft 62 of the lifting device 8 is located at the center in the width direction of the automated guided vehicle 1 and at the center in the front-rear direction of the top plate 64. In addition, this screw shaft 62 is located on the rotation axis X2 of the left and right drive wheels 3a and 3b, and the rotation axis X0 of the lift base 5 and swing arm 6 is located in front of the rotation axis X2.

[0027] Next, the operation of the automated guided vehicle 1, which has the above configuration, will be explained. When the automated guided vehicle 1 is moving, the drive sources (motors) 4a and 4b are driven by external instructions, and the left and right drive wheels 3a and 3b are rotated, causing the automated guided vehicle 1 to move. In this case, the vehicle is steered freely by the speed difference between the left and right drive wheels 3a and 3b.

[0028] For example, after stopping its movement under a load, the automated guided vehicle 1 activates the lifting device 8 to raise the top plate 64 and place the load on the top plate 64. At this time, the lifting plate 65 that supports the top plate 64 is provided with an engaging recess 66, and this engaging recess 66 is guided only upward by the guide projection 26 while its movement in the forward, backward, left, and right directions is restricted.

[0029] In this state, the load can be transported to the desired location as needed. In this case, stable operation is possible if the load on the top plate 64 is placed so that the load is evenly distributed across the entire surface of the top plate 64, but there are cases where the load is unevenly distributed. In this automated guided vehicle 1, stable operation is possible even if the load is unevenly distributed.

[0030] In other words, if there is an uneven load in the way the load is stacked, the lift base 5 rotates around the rotation axis X0 of the shaft 23, and the caster frame 45 rotates around the rotation axis X1 of the shaft 44. In this way, the left and right drive wheels 3a, 3b and the left and right driven wheels 46a, 46b make contact with the running surface while maintaining an appropriate frictional force, preventing excessive load from being applied to a particular wheel and causing the wheel on the opposite line to lift off the ground or come close to lifting off the ground. As a result, stable operation of the automated guided vehicle 1 is ensured.

[0031] In this case, the left and right driven wheels 7a and 7b are less susceptible to the effects of uneven loads due to the relationship between the front-to-rear center position of the top plate 64, that is, the position where the screw shaft 62 is located, and the position of the rotation axis X0 of the lift base 5 and swing arm 6, and always make contact with the running surface with appropriate frictional force. In this way, the automated guided vehicle 1 can run stably because each wheel makes contact with the running surface with appropriate frictional force.

[0032] Furthermore, in order to achieve stable driving against uneven loads during vehicle operation, it is conceivable to arrange the left and right wheels on a single axle, and then place a third wheel behind (or in front of) these left and right wheels to provide three-point support. This three-point support prevents any of the wheels from lifting off the ground in the event of an uneven load.

[0033] In this regard, the automated guided vehicle 1 has left and right drive wheels 3a and 3b located outward in the vehicle width direction of the vehicle frame 2. Furthermore, the left and right driven wheels 46a and 46b are located behind the left and right drive wheels 3a and 3b, and are located inward in the vehicle width direction from the left and right drive wheels 3a and 3b, so that an effect close to a pseudo three-point support is obtained, enabling stable driving.

[0034] Furthermore, this effect is not limited to cases where the load is unevenly distributed; the same effect is obtained even when the running surface is uneven, thus enabling stable driving. In addition, since the automated guided vehicle 1 can drive stably even when unloaded, it can drive stably in both unloaded and unevenly loaded conditions.

[0035] Furthermore, when the automated guided vehicle 1 is to slide under a box pallet or the like to place a load, it is desirable to keep the vehicle height as low as possible. In this regard, the branch arms 41a and 41b of the swing arm 6 of the automated guided vehicle 1 are formed in an arch shape, and the drive sources (motors) 4a and 4b for driving are located below them. Therefore, the vehicle height in the part where the drive sources (motors) 4a and 4b are installed can be kept low, and the requirement for a low vehicle height can be met.

[0036] In the above embodiment, the automated guided vehicle 1 is configured to support the left and right driven wheels 46a and 46b, located behind the left and right drive wheels 3a and 3b, with a swing arm 6, and to support this swing arm 6 with the rotation axis X1 of the shaft body 44. In addition to this configuration, the automated guided vehicle 1 may also be configured to support the left and right driven wheels 7a and 7b, located in front of the vehicle frame 2, with a swing arm 6, depending on the characteristics of the load, and to be rotatable.

[0037] 1. Automated Guided Vehicle (AGV) 2. Body Frame 3a, 3b Drive Wheels 4a, 4b Motor 5. Lift Base 6. Swing Arm 7a, 7b Driven Wheel 8. Lifting Device 23. Shaft 41a, 41b Branch Arm 44. Shaft 45. Caster Frame 46a, 46b Driven Wheel 61. Lift Lifting Section 63. Drive Mechanism

Claims

1. An automated guided vehicle (AGV) that can travel in the front-rear direction, comprising: a body frame; left and right drive wheels provided spaced apart in the width direction of the body frame; a drive source for driving the left and right drive wheels; a lift base supported on the body frame so as to be rotatable along an axis in the width direction; a swing arm having left and right branch arms, each having its base ends fixed to the left and right ends of the lift base, with its intermediate portion extending in either the front-rear direction or the other, and its rear ends connected at a position a certain distance away from the left and right drive wheels; a driven wheel provided at the connection point of the left and right branch arms; and a lifting device including the lift base for lifting and lowering loads.

2. The connecting portion is provided with a caster frame that is rotatable on an axis extending in the front-rear direction at the center in the vehicle width direction, and a pair of driven wheels are provided at each of the outer ends in the vehicle width direction of the caster frame, which are located inward in the vehicle width direction from the left and right drive wheels, according to claim 1.

3. The unmanned transport vehicle according to claim 1, wherein the left and right branch arms of the swing arm are each formed in an arch shape, rising upward from one end in the front-rear direction and then descending toward the other end, and the left and right drive sources for driving the left and right drive wheels are provided below these branch arms.

4. The left and right drive wheels are provided on the vehicle body frame outward in the vehicle width direction, as described in claim 1.

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