automated guided vehicle

Abstract

To provide an unmanned transport vehicle equipped with a lifting device for lifting and lowering a load placed thereon, capable of running stably even with an unbalanced load. [Solution] An unmanned guided vehicle that can travel freely in a forward and backward direction, comprising: a body frame; left and right drive wheels spaced apart in the vehicle width direction of the body frame; a driving source for driving the left and right drive wheels; a lift base supported on the body frame so as to be rotatable about an axis in the vehicle width direction; a swing arm having left and right branch arms whose base ends are fixed to the left and right ends of the lift base, whose middle parts extend in either the forward and backward directions, and whose rear ends are connected at a position spaced a certain distance from the left and right drive wheels; driven wheels provided at the connecting parts of the left and right branch arms; and a lifting device that includes the lift base and lifts and lowers loads placed on it.

Description

[Technical Field]

[0001] The present invention relates to an automated guided vehicle. [Background technology]

[0002] In recent years, automated guided vehicles (AGVs), which enable the automatic movement of goods without human intervention, have come into use in factories and logistics sites. For example, Patent Document 1 discloses an automated guided vehicle in which caster wheels are provided at each of the four corners of a carriage on which a load is placed, front, rear, left and right, and further a drive wheel is provided in the center of the carriage. Furthermore, Patent Document 2 discloses an automated guided vehicle that has caster wheels at the four corners of a frame equipped with a lifting mechanism for placing and raising and lowering a load, and further has steered drive wheels at two locations, front and back, in the center of the frame. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-33027 [Patent Document 2] JP 2011-88500 A Summary of the Invention [Problem to be solved by the invention]

[0004] In both Patent Documents 1 and 2, driven wheels are provided at the front, rear, left and right corners of the carriage (frame), and a drive wheel is provided in the center of the carriage (frame). Therefore, if a load is placed on the carriage or on the lifting device and the load is placed in an unbalanced state, when the transport vehicle is driven, excessive weight is applied to one of the driven wheels, causing the vehicle to run unstably. In other words, the driven wheel diagonally opposite the driven wheel to which the excessive weight is applied will lift up or nearly lift up, causing the driven wheel to make insufficient contact with the running surface, resulting in unstable running. This type of problem can become a major issue in transport vehicles equipped with a lifting device for loading loads, as the height of the load placed on the lifting device can lead to even more unstable running.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and the problem that the present invention aims to solve is to provide an unmanned guided vehicle equipped with a lifting device for placing a load on it and lifting it up and down, which can run stably even when the load is unevenly loaded. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention employs the following means. In other words, the unmanned guided vehicle of the present invention is an unmanned guided vehicle that can travel freely in a forward and backward direction, and is configured to include a body frame, left and right drive wheels spaced apart in the vehicle width direction of the body frame, a driving source for driving the left and right drive wheels, a lift base supported on the body frame so as to be rotatable about an axis in the vehicle width direction, a swing arm having left and right branch arms whose base ends are fixed to the left and right ends of the lift base, whose middle parts extend in either the forward and backward directions, and whose rear ends are connected at a position spaced a certain distance from the left and right drive wheels, driven wheels provided at the connecting parts of the left and right branch arms, and a lifting device that includes the lift base and lifts and lowers loads placed on it.

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

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

[0009] In another aspect of the present invention, the left and right drive wheels are provided outward in the vehicle width direction of the body frame. [Effects of the Invention]

[0010] According to the present invention, an automatic guided vehicle equipped with a lifting device can travel stably even with an uneven load. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a plan view showing the basic configuration of an automatic guided vehicle shown as an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view of the automated guided vehicle taken along line AA in FIG. 1. [Figure 3] FIG. 2 is a front view showing the basic configuration of the automatic guided vehicle. [Figure 4] 4 is a plan view of the automated guided vehicle taken along line BB in FIG. 3. [Figure 5] FIG. 2 is a side view showing the basic configuration of the automatic guided vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0013] In Figures 1 to 4, the unmanned guided vehicle 1 comprises a vehicle body frame 2, left and right drive wheels 3a, 3b, traveling drive sources (motors) 4a, 4b, a lift base 5, a swing arm 6, left and right driven wheels 7a, 7b, and a lifting device 8.

[0014] The automated guided vehicle 1 can travel in the direction of arrow F and the opposite direction of arrow B, and for convenience in the following explanation, arrow F will be referred to as the forward direction and arrow B as the backward direction. The automated guided vehicle 1 can change its direction of travel by varying the rotational speeds of the left and right drive wheels 3a, 3b. The automatic guided vehicle 1 is designed so that its running state, the up and down movement of the lifting device 8, etc. are controlled by external wireless commands.

[0015] As shown in Figures 1 and 4, the body frame 2 includes a front wall 21 and left and right side walls 22a, 22b extending rearward from the front wall 21. Left and right drive wheels 3a, 3b are rotatably attached to the outside of the side walls 22a, 22b, respectively. Drive sources (motors) 4a, 4b for driving the drive wheels 3a, 3b are provided inside the side walls 22a, 22b. The drive sources (motors) 4a, 4b are disposed adjacent to the left and right drive wheels 3a, 3b, respectively. The front wall portion 21 is provided with left and right driven wheels 7a, 7b configured as casters.

[0016] A shaft 23 is rotatably supported between the longitudinal centers of the side walls 22a, 22b of the body frame 2. A lift base 5 is provided on the shaft 23, and the lift base 5 is rotatable about the rotation axis X0 of the shaft 23.

[0017] As shown in Figure 2, the lift base 5 is a structure having a main wall 24 rising upward from the shaft 23 and a horizontal wall 25 extending rearward from the lower end of the main wall 24, and two guide protrusions 26, 26 are provided on the rear surface of the main wall 24, spaced apart on the left and right.

[0018] 1 and 4, the base end of a swing arm 6 is fixed to the left and right ends of the lift base 5. The swing arm 6 has a middle portion extending in either the front or rear direction. The swing arm 6 includes left and right branch arms 41a, 41b and connecting rods 42a, 42b provided between the rear ends of the left and right branch arms 41a, 41b. The connecting rods 42a, 42b are arranged at a fixed distance from the rear ends of the left and right branch arms 41a, 41b, and the rectangular portion formed by the connecting rods 42a, 42b and the left and right branch arms 41a, 41b constitutes a connecting portion 43 between the left and right branch arms 41a, 41b.

[0019] 1, 4, and 5, an axle 44 is provided at the center of the connecting rods 42a, 42b in the vehicle width direction, extending between these connecting rods 42a, 42b and extending in the front-to-rear direction of the body frame 2. A caster frame 45 is supported on the axle 44 so as to be rotatable about a rotation axis X1 of the axle 44. A pair of left and right driven wheels 46a, 46b configured as casters is provided on 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, 46b are located inward in the vehicle width direction from the left and right drive wheels 3a, 3b.

[0020] The swing arm 6 configured in this manner can rotate freely together with the lift base 5 around the shaft 44 within a vertical plane. The left and right branch arms 41a, 41b of the swing arm 6 are formed in an arch shape, rising upward from one end where the longitudinal connecting rods 42a, 42b are respectively provided, and descending toward the other end where the lift base 5 is provided, and left and right running drive sources (motors) 4a, 4b that drive the left and right drive wheels 3a, 3b, respectively, are provided below these branch arms 41a, 41b.

[0021] 2, the lifting device 8 includes a lift base 5, and is equipped with a lift lifting unit 61, a screw shaft 62, and a drive mechanism 63 that rotates and drives the screw shaft 62. The lift lifting unit 61 is equipped with a top plate 64 on which a load is placed, a lifting plate 65 that is provided on the underside of the top plate 64 and extends downward, an engaging recess 66 that is provided on the lifting plate 65 and engages with the guide protrusion 26, and a female screw member 67 that is provided on the lifting plate 65 and into which the screw shaft 62 is screwed.

[0022] The guide protrusions 26 and the engagement recesses 66 allow the lift plate 65 to move only in the up and down direction, and restrict movement in the front, back, left and right directions (configured as a so-called linear guide).

[0023] As shown in Figure 2, the screw shaft 62 is provided so as to protrude upward from the horizontal wall 25 of the lift base 5. The screw shaft 62 is rotated by a drive mechanism 63 provided on the horizontal wall 25. The drive mechanism 63 includes a motor 81, a sprocket wheel 82 provided on the rotating shaft of the motor 81, a sprocket wheel 83 provided on the lower end of the screw shaft 62, and a chain 84 wound between the sprocket wheels 82 and 83.

[0024] The drive mechanism 63 is not limited to the combination of the sprocket wheel 83 and the chain 84 wound between the sprocket wheels 82 and 83, but may also use a combination of gears, a timing belt and a pulley, or the like.

[0025] With this configuration, when the motor 81 is driven to rotate the screw shaft 62, the female screw member 67 moves up and down, thereby moving the lift plate 65 and the top plate 64 up and down. At this time, the lift lifting unit 61 can only move up and down because the engaging recess 66 is guided by the guide protrusion 26.

[0026] In the above configuration, the optimal load ratio for achieving stable driving on these wheels is determined by the dimensional ratio between the distance L1 from the left and right driving wheels 3a, 3b to the rotation axis X0 of the axle 23, the distance L2 from the left and right driven wheels 7a, 7b to the rotation axis X0 of the axle 23, and the distance L3 from the left and right driven wheels 46a, 46b to the rotation axis X0 of the axle 23. This load ratio is set on the premise that stable running is possible when there is no load.

[0027] In the above configuration, the screw shaft 62 of the lifting device 8 is located at the center of the automatic guided vehicle 1 in the vehicle width direction and at the center position of the top plate 64 in the front-rear direction. The screw shaft 62 is also located on the rotation axis X2 of the left and right drive wheels 3a, 3b, and the rotation axis X0 of the lift base 5 and swing arm 6 is located forward of the rotation axis X2.

[0028] Next, the operation of the automatic guided vehicle 1 having the above configuration will be described. When the automated guided vehicle 1 is to travel, the left and right drive wheels 3a, 3b are rotated and driven by driving the travel drive sources (motors) 4a, 4b in response to an external command, causing the automated guided vehicle 1 to travel. In this case, the vehicle is steered so as to travel freely due to the speed difference between the left and right drive wheels 3a, 3b.

[0029] For example, after the automatic guided vehicle 1 stops traveling under a load, the lifting device 8 is activated to raise the top plate 64 and place the load on the top plate 64. At this time, an engagement recess 66 is provided on the lift plate 65 supporting the top plate 64, and this engagement recess 66 is guided only upward by the guide protrusion 26 while being restricted from moving in the front-rear and left-right directions.

[0030] In this state, the load can be transported to the desired location as appropriate. In this case, stable travel is possible if the load on the top plate 64 is placed so that the load is evenly distributed across the entire top plate 64, but there are cases where the load is placed in an unbalanced manner. This automatic guided vehicle 1 is able to travel stably even if the load is loaded in an unbalanced manner.

[0031] That is, if the load is unevenly loaded, 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. This allows the left and right drive wheels 3a, 3b and the left and right driven wheels 46a, 46b to contact the road surface while maintaining an appropriate frictional force between them, preventing excessive load from being applied to a particular wheel and causing the wheel on the opposite line to lift up or become close to lifting up, ensuring stable travel of the automated guided vehicle 1.

[0032] In this case, the left and right driven wheels 7a, 7b are less susceptible to the effects of unbalanced loads due to the relationship between the longitudinal center position of the top plate 64, i.e., 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 are always in contact with the running surface with appropriate frictional force. In this way, the automatic guided vehicle 1 can travel stably because each wheel comes into contact with the traveling surface with an appropriate frictional force.

[0033] Furthermore, in order to ensure stable running of a vehicle in the event of an unbalanced load, it is possible to, for example, arrange the left and right wheels on a single axis and arrange one wheel behind (or in front of) the left and right wheels to provide three-point support. Such three-point support can prevent any of the wheels from lifting up in the event of an unbalanced load.

[0034] In this regard, the unmanned guided vehicle 1 has left and right drive wheels 3a, 3b located outside the vehicle body frame 2 in the vehicle width direction, and furthermore, the left and right driven wheels 46a, 46b are located behind the left and right drive wheels 3a, 3b and are located inside the left and right drive wheels 3a, 3b in the vehicle width direction, so that an action similar to a three-point support is obtained, enabling stable driving.

[0035] Furthermore, the same effect can be obtained not only when there is an uneven load due to the way the cargo is loaded, but also when the traveling surface is uneven, allowing for stable traveling. Furthermore, the automatic guided vehicle 1 can run stably when there is no load, and therefore can run stably both when there is no load and when there is an unbalanced load.

[0036] Furthermore, when an automated guided vehicle needs to slip under a box pallet or the like to place a load, it is desirable to have a vehicle height as low as possible. In this regard, the automated guided vehicle 1 has branch arms 41a, 41b of the swing arm 6 formed in an arch shape, and the traveling drive sources (motors) 4a, 4b are arranged below these, so that the vehicle height at the portions where the traveling drive sources (motors) 4a, 4b are provided can be kept low, and the demand for a low vehicle height can be met.

[0037] In the above embodiment, the left and right driven wheels 46a, 46b located behind the left and right drive wheels 3a, 3b are supported by the swing arm 6, and this swing arm 6 is supported by the rotation axis X1 of the shaft body 44. However, in addition to this configuration, depending on the characteristics of the load, the left and right driven wheels 7a, 7b located in front of the body frame 2 may also be supported by the swing arm 6 and configured to be freely rotatable. [Explanation of symbols]

[0038] 1. Automated guided vehicle 2 Body frame 3a, 3b driving wheels 4a, 4b: Driving source (motor) 5 Lift base 6 Swingarm 7a, 7b Driven wheel 8 Lifting device 23 Axial body 41a, 41b branch arms 44 shaft body 45 Caster frame 46a, 46b Driven wheel 61 Lift lift section 63 Drive mechanism

Claims

1. An automated guided vehicle that can travel freely in the forward and backward directions, The body frame and left and right drive wheels spaced apart in a vehicle width direction of the body frame; a driving source for driving the left and right drive wheels; a lift base portion rotatably supported on the vehicle body frame with an axis spaced a predetermined distance in either the front-rear direction from the rotation axes of the left and right drive wheels in the vehicle width direction; a swing arm having left and right branch arms whose base ends are fixed to the left and right ends of the lift base, whose intermediate portions extend from the base ends in either the front-rear direction or the rear direction, and whose tip ends are connected at positions spaced apart from the left and right drive wheels as viewed from the axis; a driven wheel provided at a connecting portion of the left and right branch arms; a lifting device that includes the lift base and that places and lifts a load, The connecting portion is provided with a caster frame that is rotatable about an axis extending in the front-rear direction at the center of the vehicle width direction, An automated guided vehicle, wherein a pair of driven wheels positioned inward in the vehicle width direction from the left and right drive wheels are provided at each of the outer ends in the vehicle width direction of the caster frame.

2. The left and right branch arms of the swing arm are each formed in an arch shape that rises upward from one end in the front-rear direction and then descends toward the other end, 2. The automated guided vehicle according to claim 1, wherein the left and right travel drive sources for driving the left and right drive wheels, respectively, are provided below the branch arms.

3. 2. The automated guided vehicle according to claim 1, wherein the left and right drive wheels are provided on outer sides of the body frame in a vehicle width direction.

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