Transport vehicle

Abstract

To provide a conveyance vehicle capable of smoothly traveling even when an inclined surface or waviness in which a road surface is displaced toward a longitudinal direction and a horizontal direction locally occurs.SOLUTION: A conveyance vehicle includes a first wheel part W1 positioned on a front end part of a base N and a second wheel part W2 and a third wheel part W3 independent from each other. The first wheel part W1 has a horizontal frame body 1 and right and left swivel wheels 4 and 5 of the horizontal frame body 1. An intermediate position between the swivel wheels 4 and 5 of the horizontal frame body 1 is supported to the base N so as to be swingable around a longitudinal shaft Y1. The second wheel part W2 and the third wheel part W3 have longitudinal frame bodies 2 and 3, drive wheels 9 and 10 provided at front and rear of the longitudinal frame bodies 2 and 3, and swivel wheels 6 and 7. An intermediate position between the drive wheels 9 and 10 of the longitudinal frame bodies 2 and 3 and the swivel wheels 6 and 7 is supported to the base N so as to be swingable around horizontal shafts X2 and X3 and longitudinal shafts Y2 and Y3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a self-propelled transport vehicle equipped with left and right drive wheels. [Background technology]

[0002] A self-propelled transport vehicle equipped with left and right drive wheels has wheel sections on the left and right sides of a base of the transport vehicle, with drive wheels and driven wheels arranged at the front and rear of a longitudinal frame body extending in the longitudinal direction, and the intermediate position between the drive wheels and driven wheels on the longitudinal frame body is supported so as to be swingable around a left-right axis relative to the base (see, for example, Patent Document 1).

[0003] The structure of the transport vehicle 10 of Patent Document 1, which is a self-propelled transport vehicle equipped with left and right drive wheels, is as follows.

[0004] That is, the transporter 10 has a swing frame 22 that is rotatable about a pivot 24, which is a widthwise (left-right) axis, provided below two left and right piece members 14a and 14b that extend in the longitudinal direction (front-rear direction) of the frame member 14. At one end and the other end in the front-rear direction of the swing frame 22, a driving wheel 28, which is a driving wheel driven by a driving unit 40, and a swivel wheel 30, which is a driven wheel, are arranged, respectively.

[0005] Holder members 38, 38 are provided on the underside of the other front-rear ends of the piece members 14a, 14b of the transporter 10, and swivel wheels 36, 36, which are left and right driven wheels, are attached to the underside of the holder members 38, 38.

[0006] When the transport vehicle 10 travels on a slope or a road with unevenness or steps, the drive wheels 28 and the swivel wheels 30 are moved up and down by the left and right swing frames 22 which can swing independently and rotatably about the pivots 24 as fulcrums. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-71245 Summary of the Invention [Problem to be solved by the invention]

[0008] In the transport vehicle 10 of Patent Document 1, for example, even if the drive wheels 28 or swivel wheels 30 arranged on the swing frame 22 run over a step, the left and right swing frames 22, 22 can swing independently, allowing the wheels that are not running over the step to touch the ground. Therefore, with this configuration, the transport vehicle 10 of Patent Document 1 is able to adapt to uneven road surfaces and travel smoothly on slopes and roads with undulations and steps. However, although the configuration of the transport vehicle 10 of Patent Document 1 has a certain effect of adapting to uneven road surfaces, there is room for improvement as follows:

[0009] That is, in the transporter 10 of Patent Document 1, the swing frame 22 can swing only about the left-right axis. Therefore, when the road surface has a localized inclined surface or undulation that displaces in the fore-aft direction, the transporter 10 can travel smoothly on the road surface. However, when the road surface has a localized inclined surface or undulation that displaces in the left-aft direction, the swing frame 22 of the transporter 10 cannot swing about the fore-aft axis, and therefore sufficient ground contact cannot be ensured not only for the swivel wheels 36 but also for the drive wheels 28 and 30. In this case, problems arise, such as the inability to ensure frictional force of the drive wheels 28 and the inability to obtain sufficient thrust.

[0010] Furthermore, because the left and right swivel wheels 36, 36 are attached to the holding members 38, 38, they cannot move up and down relative to the frame member 14 like the drive wheels 28 and swivel wheels 30. Therefore, if the swivel wheel 36 gets stuck in a groove or rides over a step, one of the swivel wheels 30, 36 may lift up, hindering smooth running.

[0011] An object of the present invention is to provide a transport vehicle that can travel smoothly even when the road surface is locally inclined or undulating, with the road surface displacing in the forward / backward and left / right directions. [Means for solving the problem]

[0012] A transport vehicle according to a first aspect of the present invention is a transport vehicle equipped with left and right drive wheels, and includes a first wheel unit located at the front or rear end of a base of the transport vehicle, and independent second and third wheel units located on the left and right sides behind or in front of the first wheel unit. The first wheel unit includes a left-right frame body extending in the left-right direction and a pair of swivel wheels as driven wheels located on the left and right sides of the left-right frame body. An intermediate position between the left swivel wheel and the right swivel wheel on the left-right frame body is supported so as to be swingable around a front-to-rear axis with respect to the base. The second and third wheel units include a front-to-rear frame body extending in the front-to-rear direction, the drive wheel located at the front or rear of the front-to-rear frame body, and a swivel wheel as driven wheel located at the rear or front of the front-to-rear frame body. An intermediate position between the drive wheel and the swivel wheel on the front-to-rear frame body is supported so as to be swingable around the left-to-right axis and the front-to-rear axis with respect to the base.

[0013] A transport vehicle according to a second aspect of the present invention is a transport vehicle equipped with left and right drive wheels, and includes a first wheel unit located at the front or rear end of a base of the transport vehicle, and independent second and third wheel units located on the left and right sides behind or in front of the first wheel unit. The first wheel unit has one or more swivel wheels which are driven wheels located in the center of the base in the left-right direction. The second and third wheel units include a front-to-rear frame body extending in the front-to-rear direction, the drive wheel located at the front or rear of the front-to-rear frame body, and the swivel wheels which are driven wheels located at the rear or front of the front-to-rear frame body. The front-to-rear frame body is supported at an intermediate position between the drive wheel and the swivel wheels so as to be swingable about a left-to-right axis and a front-to-rear axis with respect to the base.

[0014] In the transport vehicle according to the first aspect of the present invention and the transport vehicle according to the second aspect of the present invention, the longitudinal frame bodies of the second wheel unit and the third wheel unit can swing independently about a lateral axis with respect to the base of the transport vehicle. Therefore, even if the road surface has a localized slope or undulation that displaces in the longitudinal direction, the drive wheels and swivel wheels of the second wheel unit and the third wheel unit can contact the road surface so as to follow the road surface. Therefore, the contact area of ​​the drive wheels and swivel wheels of the second wheel unit and the third wheel unit with the road surface is increased, ensuring sufficient contact with the road surface, allowing the transport vehicle to travel smoothly.

[0015] In the transport vehicle according to the first aspect of the present invention and the transport vehicle according to the second aspect of the present invention, the longitudinal frame body can swing independently about a longitudinal axis relative to the base. Therefore, even if the road surface is locally inclined or undulated in the lateral direction, the drive wheels and swivel wheels of the second wheel unit and the third wheel unit can contact the road surface so as to follow the road surface. This increases the contact area of ​​the drive wheels and swivel wheels of the second wheel unit and the third wheel unit with the road surface, ensuring sufficient contact with the road surface, allowing the transport vehicle to travel smoothly.

[0016] According to the transport vehicle of the first aspect of the present invention, the left-right frame body of the first wheel unit can swing about a front-rear axis relative to the base of the transport vehicle. Therefore, even if one of the left and right swivel wheels of the left-right frame body gets stuck in a groove or rides over a step, the other swivel wheel will contact the ground, allowing the transport vehicle to run smoothly.

[0017] According to the transport vehicle of the second aspect of the present invention, the swivel wheels of the first wheel unit are located in the center of the base in the left-right direction, which allows for ample space to be secured on both the left and right sides of the first wheel unit, greatly increasing the degree of freedom in installing sensors and wiring.

[0018] A transport vehicle according to a third aspect of the present invention is a transport vehicle according to the first aspect, wherein an intermediate position between the left-side swivel wheel and the right-side swivel wheel on the left-side frame body is further supported so as to be swingable around a left-side axis relative to the base.

[0019] A transport vehicle according to a fourth aspect of the present invention is the transport vehicle according to the second aspect, wherein a swivel wheel of the first wheel unit is supported so as to be swingable about a left-right axis relative to the base.

[0020] In the transport vehicle according to the third aspect of the present invention and the transport vehicle according to the fourth aspect of the present invention, the swivel wheels of the first wheel unit can swing about a left-right axis with respect to the base. Therefore, when the swivel wheels of the first wheel unit face left-right (circumferential direction of the spin turn) while the transport vehicle is making a spin turn, even if there is an inclined surface in the front-rear direction (radial direction of the spin turn), the swivel wheels of the first wheel unit can come into contact with the ground so as to follow the inclined surface. Therefore, the contact area of ​​the swivel wheels of the first wheel unit with the road surface is increased, ensuring sufficient contact with the ground, allowing the transport vehicle to travel smoothly.

[0021] A transport vehicle according to a fifth aspect of the present invention is the transport vehicle according to the first aspect or the transport vehicle according to the second aspect, wherein the mechanism that supports the intermediate position between the drive wheel and the swivel wheel in the longitudinal frame body so that it can swing around the left-right axis and the longitudinal axis relative to the base is a first hinge that swings around the left-right axis and a second hinge that swings around the longitudinal axis, which are provided between the base and the longitudinal frame body.

[0022] According to the transport vehicle of the fifth aspect of the present invention, the mechanism that supports the longitudinal frame body so that it can swing is the first hinge and the second hinge, making it easy to set the required swing angle in the two axial directions and to ensure rigidity and strength.

[0023] A transport vehicle according to a sixth aspect of the present invention is the transport vehicle according to the first aspect or the transport vehicle according to the second aspect, wherein the mechanism that supports the intermediate position between the drive wheel and the swivel wheel in the longitudinal frame body so that it can swing around the left-right axis and the longitudinal axis relative to the base is an elastic body provided between the base and the longitudinal frame body.

[0024] According to the transport vehicle of the sixth aspect of the present invention, the mechanism that supports the longitudinal frame body so that it can swing is an elastic body, so that the simple structure reduces manufacturing costs, and the cushioning effect of the elastic body can suppress the transmission of vibrations from the road surface to the base of the transport vehicle.

[0025] A transport vehicle according to a seventh aspect of the present invention is the transport vehicle according to the first aspect or the transport vehicle according to the third aspect, wherein the left-right length of the left-right frame body is smaller than the left-right distance between the left and right front-rear frame bodies.

[0026] According to the transport vehicle of the seventh aspect of the present invention, the length of the left-right frame body of the first wheel unit in the left-right direction is smaller than the distance between the left and right front-rear frame bodies in the left-right direction, which allows space to be secured on both the left and right sides of the first wheel unit, increasing the degree of freedom in installing sensors and wiring them.

[0027] A transport vehicle according to an eighth aspect of the present invention is any of the transport vehicles according to the first aspect, the third aspect, the fifth aspect, the sixth aspect, and the seventh aspect, wherein the front-to-rear distance between the rotation center axis of the drive wheel of the second wheel unit and the vertical support axis of the swivel wheel of the second wheel unit, the front-to-rear distance between the rotation center axis of the drive wheel of the third wheel unit and the vertical support axis of the swivel wheel of the third wheel unit, and the front-to-rear distance between the rotation center axis of the drive wheel or the vertical support axis of the swivel wheel of the drive wheel or the swivel wheel that is closer to the first wheel unit in the second wheel unit and the third wheel unit, are the same or approximately the same. The front-to-rear frame body is supported at or near the front-to-rear center between the rotation center axis of the drive wheel and the vertical support axis of the swivel wheel with respect to the base so as to be swingable about the left-right axis and the front-to-rear axis.

[0028] According to the transport vehicle of the eighth aspect of the present invention, the load is evenly or approximately evenly distributed across the six drive wheels and swivel wheels, and the drive wheels can reliably transmit the necessary driving force to the road surface while the transport vehicle travels. By evenly or approximately evenly distributing the load across the six wheels, the load on the swivel wheels can be reduced, and the drive wheels are not subjected to excessive load. Therefore, both the swivel wheels and the drive wheels can be designed with the minimum necessary allowable load, thereby reducing the cost of the wheels.

[0029] The "base" in the transport vehicle according to the present invention is a structural member of the transport vehicle, and includes a structure in which a frame, a rod, etc. are combined.

[0030] In the transport vehicle according to the present invention, the "intermediate position" of the "intermediate position between the left swivel wheel and the right swivel wheel" may be the center position between the left swivel wheel and the right swivel wheel, or it does not have to be the center position. In other words, the "intermediate position" may be any position between the left swivel wheel and the right swivel wheel.

[0031] In the transport vehicle according to the present invention, the "intermediate position" of the "intermediate position between the drive wheel and the swivel wheel" may be the center position between the drive wheel and the swivel wheel, or it may not be the center position. In other words, the "intermediate position" may be any position between the drive wheel and the swivel wheel.

[0032] In the transport vehicle of the present invention, the "lateral center" of "one or more swivel wheels serving as driven wheels, located in the lateral center of the base" is a concept that includes the lateral center and its vicinity. "Swivel wheels" also include, for example, multiple wheels arranged in the direction of the central axis of rotation for heavy loads. "Multiple swivel wheels" may be, for example, three "swivel wheels" arranged in a horizontal plane. From the perspective of balance when the transport vehicle turns left and right, it is preferable to arrange the "swivel wheels serving as driven wheels" so that they are plane-symmetrical with the vertical plane in the lateral center of the base of the transport vehicle, with the wheels of the "swivel wheels" facing forward and backward. [Effects of the Invention]

[0033] According to the transport vehicle of the present invention, the longitudinal frame bodies of the second wheel unit and the third wheel unit can swing independently about a left-right axis relative to the base of the transport vehicle. Therefore, even if the road surface has a slope or undulation that displaces longitudinally, the drive wheels and swivel wheels of the second wheel unit and the third wheel unit can contact the road surface. This increases the contact area of ​​the drive wheels and swivel wheels of the second wheel unit and the third wheel unit with the road surface, ensuring sufficient contact with the road surface, allowing the transport vehicle to travel smoothly.

[0034] Furthermore, the longitudinal frame bodies of the second wheel unit and the third wheel unit can swing independently about longitudinal axes relative to the base. Therefore, even if the road surface is locally inclined or undulated in the lateral direction, the drive wheels and swivel wheels of the second wheel unit and the third wheel unit can contact the road surface. This increases the contact area of ​​the drive wheels and swivel wheels of the second wheel unit and the third wheel unit with the road surface, ensuring sufficient contact with the road surface and allowing the transport vehicle to travel smoothly. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a perspective view of a transport vehicle according to an embodiment of the present invention. [Figure 2] 3 is a perspective view showing a first wheel portion, a second wheel portion, and a third wheel portion of the transport vehicle. FIG. [Figure 3A] FIG. [Figure 3B] FIG. 10 is a front view of a first wheel unit showing a modified example in which the length of the left-right frame body is shortened. [Figure 3C] FIG. 10 is a front view of a first wheel section showing a modified example in which the left-right frame body is eliminated. [Figure 4] 3C is a plan view showing the first wheel portion, the second wheel portion, and the third wheel portion of the modified example of FIG. 3B. FIG. [Figure 5] FIG. 3 is a right side view of the second wheel unit of FIG. 2. [Figure 6] 6 is a cross-sectional view taken along the line Z1-Z1 in FIG. 5. [Figure 7] FIG. 2 is a perspective view of a first hinge and a second hinge. [Figure 8] 3D is a perspective view showing a first wheel portion of the modified example of FIG. 3C, and a modified second wheel portion and a modified third wheel portion. FIG. [Figure 9] FIG. 10 is a perspective view showing a modified example of the second wheel section and the third wheel section. [Figure 10] FIG. 10 is a right side view of the second wheel unit of FIGS. 8 and 9. [Figure 11] 11 is a cross-sectional view taken along the line Z2-Z2 in FIG. 10. [Figure 12]10 is a perspective view showing an example of a structure for supporting a swivel wheel of a first wheel section so as to be swingable about two axes. FIG. [Figure 13] FIG. 13 is a partial cross-sectional right side view showing the state in which the transport vehicle of FIG. 12 is making a spin turn, in which the road surface is a spherically curved surface that is concave upward. [Figure 14] This is a partial cross-sectional right side view for explaining the operation of a transport vehicle in an embodiment of the present invention, and shows an example in which the shape of a road surface cut by a vertical plane including the front-to-back direction when viewed from the left and right directions is a cylindrical curved surface with an upward convex arc shape. [Figure 15] This is a partial cross-sectional right side view for explaining the operation of a transport vehicle in an embodiment of the present invention, and shows an example in which the shape of a road surface cut by a vertical plane including the front-to-back direction when viewed from the left and right directions is a cylindrical curved surface with an upward concave arc. [Figure 16] This is a partial cross-sectional rear view for explaining the operation of a transport vehicle in an embodiment of the present invention, and shows an example in which the shape of a road surface cut by a vertical plane including the left and right directions when viewed from the front and back directions is a cylindrical curved surface with an upward concave arc. [Figure 17] This is a partial cross-sectional rear view for explaining the operation of a transport vehicle in an embodiment of the present invention, showing an example in which a road surface cut by a vertical plane including the left and right directions has an inclined surface as viewed from the front and back directions. [Figure 18] This is a partial cross-sectional rear view for explaining the operation of a transport vehicle in an embodiment of the present invention, showing an example in which there is a step in part of the shape of a road surface cut by a vertical plane including the left and right directions when viewed from the front and back directions. [Figure 19] FIG. 10 is a partial cross-sectional right side view illustrating equalization of the load on six wheels of the transport vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0036] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiment of the present invention, for convenience, front, back, left, and right are defined based on the orientation of the transport vehicle. That is, the arrows F, B, L, and R in the drawings represent front, back, left, and right, and a view of the transport vehicle from the front is considered a front view.

[0037] <Transport vehicle> 1 and 2, a transport vehicle A according to an embodiment of the present invention is, for example, an automated guided vehicle (AGV) that moves independently without a track. The transport vehicle A is equipped with a lift table T on which a load (not shown) is placed, and moves by driving left and right drive wheels 9 and 10.

[0038] The left and right drive wheels 9, 10 are located approximately in the center of the transport vehicle A in the front-to-rear direction. When the left and right drive wheels 9, 10 are rotated in the same direction at the same speed, the transport vehicle A moves forward or backward. When the left and right drive wheels 9, 10 are rotated in the same direction at different speeds, the transport vehicle A turns left or right while moving forward or backward. When the left and right drive wheels 9, 10 are rotated in opposite directions at the same speed, the transport vehicle A performs a spin turn, rotating in place around the center of rotation between the left and right drive wheels 9, 10.

[0039] The drive wheel 9 is driven by a drive device M1, and the drive wheel 10 is driven by a drive device M2. The drive devices M1 and M2 are each composed of a motor and a reducer, for example.

[0040] <First to third wheel parts> As shown in the perspective view of Fig. 2 and the front view of Fig. 3A, the transport vehicle A is provided with a first wheel unit W1, a second wheel unit W2, and a third wheel unit W3 on the underside of a base N. The first wheel unit W1 is located at the front end of the base N, the second wheel unit W2 is located at the left end of the base N rearward of the first wheel unit W1, and the third wheel unit W3 is located at the right end of the base N rearward of the first wheel unit W1.

[0041] The first wheel section W1 has a left-right frame body 1 extending in the left-right direction, and swivel wheels 4, 5, which are driven wheels, arranged on the left and right sides of the left-right frame body 1. An intermediate position between the swivel wheels 4 and 5 on the left-right frame body 1 is supported so as to be swingable about the front-rear axis Y1 relative to the base N. The mechanism that supports the left-right frame body 1 of the first wheel section W1 so as to be swingable about the front-rear axis Y1 relative to the base N is, for example, a hinge provided between the base N and the left-right frame body 1.

[0042] The second wheel unit W2 has a longitudinal frame body 2 extending in the front-rear direction, a driving wheel 9, and a free wheel 6, which is a driven wheel, disposed at the front and rear portions of the longitudinal frame body 2. An intermediate position between the driving wheel 9 and the free wheel 6 in the longitudinal frame body 2 is supported so as to be swingable about a lateral axis X2 and a longitudinal axis Y2 with respect to the base N.

[0043] The third wheel unit W3 has a longitudinal frame body 3 extending in the front-rear direction, a driving wheel 10, and a free wheel 7, which is a driven wheel, disposed at the front and rear portions of the longitudinal frame body 3. An intermediate position between the driving wheel 10 and the free wheel 7 in the longitudinal frame body 3 is supported so as to be swingable about a lateral axis X3 and a longitudinal axis Y3 with respect to the base N.

[0044] <Modification Example of the First Wheel Unit> The lateral frame body 1 of the first wheel unit W1 shown in the front view of FIG. 3B and the plan view of FIG. 4 is shorter than the lateral frame body 1 in the front view of FIG. 3A. In this modification example, the lateral length C of the lateral frame body 1 is made smaller than the lateral interval D between the left and right longitudinal frame bodies 2 and 3 (C < D). Thereby, spaces S1, S1 on both the left and right sides of the first wheel unit W1 can be secured, so that the degree of freedom in installing sensors and the like and wiring is increased.

[0045] As shown in the front view of FIG. 3C and the perspective view of FIG. 8, the first wheel unit W1 may be constituted only by a free wheel 8 disposed at the lateral center of the base N without the lateral frame body 1. Thereby, large spaces S2, S2 on both the left and right sides of the first wheel unit W1 can be secured, so that the degree of freedom in installing sensors and the like and wiring is extremely increased.

[0046] <Example of a Mechanism for Supporting the Longitudinal Frame Bodies of the Second to Third Wheel Units So as to Be Swingable in Two Axes> As shown in the right side view of Figure 5, the cross-sectional view of Figure 6, and the oblique view of Figure 7, the mechanism that supports the longitudinal frame body 2 of the second wheel section W2 so that it can swing about two axes around the left-right axis X2 and the front-rear axis Y2 relative to the base N is, for example, a first hinge H1 that swings about the left-right axis X2 and a second hinge H2 that swings about the front-rear axis Y2, which are provided between the base N and the longitudinal frame body 2.

[0047] The mechanism that supports the longitudinal frame body 3 of the third wheel section W3 so that it can swing biaxially around the left-right axis X3 and the longitudinal axis Y3 relative to the base N consists of a first hinge H1 and a second hinge H2, similar to that of the second wheel section W2.

[0048] By using hinges H1 and H2, which are configured with two offset axes, as a mechanism for supporting the longitudinal frame bodies 2 and 3 so that they can swing about two axes, it is easy to set the required swing angle in the two axial directions and to ensure rigidity and strength. Furthermore, by using the hinges H1 and H2, even if the center of gravity of the transport vehicle A is high due to the lift table T containing a high load, the hinges H1 and H2 can withstand shaking during travel, allowing the transport vehicle A to travel stably.

[0049] <Modification of the mechanism for supporting the longitudinal frame body of the second and third wheel sections so that it can swing on two axes> As shown in the oblique view of Figure 8, the oblique view of Figure 9, the right side view of Figure 10, and the cross-sectional view of Figure 11, the mechanism that supports the longitudinal frame body 2 of the second wheel section W2 so that it can swing around two axes about the left-right axis X2 and the front-rear axis Y2 relative to the base N, and the mechanism that supports the longitudinal frame body 3 of the third wheel section W3 so that it can swing around two axes about the left-right axis X3 and the front-rear axis Y3 relative to the base N may be an elastic body E, for example, in the form of a thick plate, provided between the base N and the longitudinal frame bodies 2, 3.

[0050] The elastic body E is, for example, an elastomer, a natural or synthetic resin with elastic properties, which can elastically return to its original shape after tensile or compressive deformation. Examples of elastomers include thermoplastic elastomers (TPE), such as TPS (styrene-based), TPO (olefin-based), TPU (urethane-based), TPA (amide-based), and TPEE (ester-based), and examples of rubber materials include nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), acrylic rubber (ACM), ethylene-acrylic rubber (AEM), fluororubber (FKM, FPM), and silicone rubber (VQM). The elastic body E is not limited to elastomers and may also be composed of multiple mechanical springs.

[0051] By using an elastic body E as a mechanism for supporting the longitudinal frame bodies 2, 3 so that they can swing about two axes, the manufacturing costs can be reduced through a simple structure, and the cushioning effect of the elastic body E can suppress the transmission of vibrations from the road surface G to the base N.

[0052] <Modification in which the swivel wheel of the first wheel section is supported so as to be swingable on two axes> As shown in the oblique view of Figure 12, the swivel wheel 8 of the first wheel section W1 may be supported by an elastic body E provided between it and the base N so as to be able to swing around two axes, the left-right axis X1 and the front-back axis Y1.

[0053] Alternatively, in a configuration with a left-right frame body 1 as shown in the oblique view of Figure 2, for example, a hinge that swings around the left-right axis X1 or an elastic body may be used to support the intermediate position between the swivel wheels 4 and 5 on the left-right frame body 1 so that it can swing around the left-right axis X1 relative to the base N.

[0054] By supporting the swivel wheel 8 of the first wheel section W1 or the left-right frame body 1 so that it can swing about the left-right axis X1, the swivel wheel 8 of the first wheel section W1 or the swivel wheels 4, 5 can swing about the left-right axis X1 relative to the base N.

[0055] Therefore, for example, when the transport vehicle A in Figure 12 performs a spin turn rotating around the vertical axis O of the base N as the center of rotation in the rotation direction K in Figure 13, even if the road surface G is, for example, a spherical curved surface P that is concave upward, when the swivel wheel 8 of the first wheel unit W1 faces left and right in Figure 13 (the circumferential direction of the spin turn) while the transport vehicle A is making the spin turn, the swivel wheel 8 of the first wheel unit W1 can come into contact with the ground so as to follow the spherical curved surface P.

[0056] Furthermore, the swivel wheel 6 that faces the circumferential direction during a spin turn can also come into contact with the ground so as to follow the spherical curved surface P, as shown in Figure 13, because the longitudinal frame body 2 of the second wheel section W2 can swing about the left-right axis X2 and the front-rear axis Y2. Similarly, the swivel wheel 7 that faces the circumferential direction during a spin turn can also come into contact with the ground so as to follow the spherical curved surface P, as the longitudinal frame body 3 of the third wheel section W3 can swing about the left-right axis X3 and the front-rear axis Y3.

[0057] Therefore, the contact area of ​​the swivel wheel 8 of the first wheel section W1 with the road surface G, as well as the contact area of ​​the swivel wheel 6 of the second wheel section W2 and the swivel wheel 7 of the third wheel section W3 with the road surface G, is increased, ensuring sufficient ground contact, allowing the transport vehicle A to perform a smooth spin turn.

[0058] <Explanation of vehicle wheel contact depending on road surface conditions> (The front-to-rear frame swings around the left-to-right axis) In the transport vehicle A according to the embodiment of the present invention, the longitudinal frame bodies 2, 3 of the second wheel section W2 and the third wheel section W3 can swing independently about the lateral axes X2, X3 relative to the base N. Therefore, as shown in the partial cross-sectional right side view of Figure 14, even when the transport vehicle A moves in the longitudinal direction on a road surface G having a cylindrical curved surface Q1 that has an upwardly convex arc shape when viewed from the lateral direction when the road surface G is cut by a vertical plane including the longitudinal direction, the drive wheels 9, 10 and the swivel wheels 4 to 7 come into contact with the road surface G.

[0059] Furthermore, as shown in the partial cross-sectional right side view of Figure 15, even when the transport vehicle A moves in the forward / backward direction on a road surface G that has a cylindrical curved surface Q2 that has an upward concave arc shape when viewed from the left and right when the road surface G is cut by a vertical plane including the forward / backward direction, the drive wheels 9, 10 and the swivel wheels 4 to 7 make contact with the road surface G.

[0060] (The longitudinal frame body swings around the longitudinal axis) In the transport vehicle A according to the embodiment of the present invention, the longitudinal frame bodies 2, 3 of the second wheel section W2 and the third wheel section W3 can swing individually about longitudinal axes Y2, Y3 relative to the base N. Therefore, as shown in the partial cross-sectional rear view of Figure 16, even when the transport vehicle A moves in the longitudinal direction on a road surface G that has a cylindrical curved surface Q3 that has an upwardly concave arc shape when viewed from the longitudinal direction and that is cut by a vertical plane including the left and right directions, the drive wheels 9, 10 and the swivel wheels 6, 7 come into contact with the road surface G.

[0061] Furthermore, as shown in the partial cross-sectional rear view of Figure 17, when a road surface G cut by a vertical plane including the left-right direction has an inclined surface I as part of its shape when viewed from the front-to-back direction, even when the transport vehicle A moves in the front-to-back direction with one of the left or right wheels, for example, the drive wheel 10 and the swivel wheel 7, positioned on the inclined surface I, the drive wheel 9 and the swivel wheel 6, and the drive wheel 10 and the swivel wheel 7, come into contact with the road surface G so as to follow the road surface G.

[0062] Furthermore, as shown in the partial cross-sectional rear view of Figure 18, when there is a step J in part of the shape of a road surface G cut by a vertical plane including the left and right directions when viewed from the front to back direction, if the left and right wheels are located above and below the step J, for example, even when the transport vehicle A moves in the front to back direction with the drive wheel 10 and the swivel wheel 7 located above the step J and the drive wheel 9 and the swivel wheel 6 located below the step J, the drive wheel 9 and the swivel wheel 6, as well as the drive wheel 10 and the swivel wheel 7, will come into contact with the road surface G so as to follow the road surface G.

[0063] (When oscillation around the left-right axis of the front-rear frame body and oscillation around the front-rear axis of the front-rear frame body occur simultaneously) When the road surface G is cut by a vertical plane including the front-to-rear direction and viewed from the left-to-right direction, the shape of the road surface G is an arc that is concave or convex upward, and when the road surface G is cut by a vertical plane including the left-to-right direction and viewed from the front-to-rear direction, the shape of the road surface G is an arc that is concave or convex upward, and even when the transport vehicle A moves in the front-to-rear direction on such a road surface G, the drive wheels 9, 10 and the swivel wheels 4 to 7 come into contact with the road surface G so as to follow the road surface G. Even when the transport vehicle A moves in the front-to-rear direction on road surfaces G of such various shapes, the drive wheels 9, 10 and the swivel wheels 4 to 7 come into contact with the road surface G so as to follow the road surface G.

[0064] As described above, according to the transport vehicle A of the embodiment of the present invention, the longitudinal frame bodies 2, 3 of the second wheel section W2 and the third wheel section W3 can swing independently about the left-right axes X2, X3 with respect to the base N. Therefore, even if the road surface G has a localized slope or undulation that displaces in the longitudinal direction, the drive wheels 9, 10 and swivel wheels 6, 7 of the second wheel section W2 and the third wheel section W3 can contact the road surface G along the road surface G. Therefore, the contact area of ​​the drive wheels 9, 10 and swivel wheels 6, 7 of the second wheel section W2 and the third wheel section W3 with the road surface G is increased, ensuring sufficient contact with the road surface G, allowing the transport vehicle A to travel smoothly.

[0065] Furthermore, the longitudinal frame bodies 2, 3 of the second wheel section W2 and the third wheel section W3 can swing individually about the longitudinal axes Y2, Y3 with respect to the base N. Therefore, even if the road surface G is locally inclined or undulated in the left-right direction, the drive wheels 9, 10 and swivel wheels 6, 7 of the second wheel section W2 and the third wheel section W3 can contact the road surface G so as to follow the road surface G. Therefore, the contact area of ​​the drive wheels 9, 10 and swivel wheels 6, 7 of the second wheel section W2 and the third wheel section W3 with the road surface G is increased, ensuring sufficient contact with the road surface G, allowing the transport vehicle A to travel smoothly.

[0066] The above-described configuration, which can increase the contact area of ​​the drive wheels 9, 10 and the swivel wheels 4 to 8 with the road surface G, can suppress uneven wear of the drive wheels 9, 10 and the swivel wheels 4 to 8, and can reliably transmit driving force from the drive wheels 9, 10 to the road surface G. Furthermore, by increasing the contact area of ​​the drive wheels 9, 10 and the swivel wheels 4 to 8 with the road surface G, it is possible to suppress wobbling of the transport vehicle A caused by the transport vehicle A losing balance while traveling.

[0067] In the above-described embodiment of the present invention, for example, in the transport vehicle A having six wheels, namely, drive wheels 9 and 10 and swivel wheels 4 to 7, as shown in Figures 2 and 9, a configuration may be adopted that further enables the load to be equalized across all six wheels. Figure 19 shows a partial cross-sectional right side view of transport vehicle A to explain the equalization of the load across all six wheels.

[0068] 9 and 19. The longitudinal distance between the vertical support axes 4A, 5A of the swivel wheels 4, 5 of the first wheel section W1 and the rotational center axes 9A, 10A of the drive wheels 9, 10 of the second wheel section W2 and the third wheel section W3 is U1. The longitudinal distance between the rotational center axis 9A of the drive wheel 9 of the second wheel section W2 and the vertical support axis 6A of the swivel wheel 6 of the second wheel section W2 is U2. The longitudinal distance between the rotational center axis 10A of the drive wheel 10 of the third wheel section W3 and the vertical support axis 7A of the swivel wheel 7 of the third wheel section W3 is U3.

[0069] 19, U1 = U2 = U3. Furthermore, the longitudinal frame bodies 2, 3 are supported at or near the longitudinal center between the rotational axis 9A, 10A of the drive wheels 9, 10 and the vertical support axis 6A, 7A of the swivel wheels 6, 7, so as to be swingable about the left-right axes X2, X3 and the front-to-rear axes Y2, Y3 with respect to the base N. For example, the longitudinal distance between the rotational axis 9A of the drive wheel 9 and the left-to-right axis X2 is (U2 / 2), and the longitudinal distance between the rotational axis 10A of the drive wheel 10 and the left-to-right axis X3 is (U3 / 2).

[0070] If the total load acting on the six wheels of transport vehicle A is V, then 1 / 6 of the total load V is acting on swivel wheels 4 to 7 and drive wheels 9 and 10. Generally, the coefficient of friction between drive wheels 9 and 10 and the road surface G is 0.5 to 0.6. Furthermore, since the rolling resistance between swivel wheels 4 to 7 and the road surface G is 0.1 or less, the rolling resistance is set to 0.1.

[0071] The normal force of the drive wheels 9 and 10 is the total load V ÷ all 6 wheels × 2 drive wheels = (1 / 3)V.

[0072] The traveling thrust of the transport vehicle A is the normal force of the drive wheels 9, 10 multiplied by the coefficient of friction between the drive wheels 9, 10 and the road surface G (0.5 to 0.6).

[0073] Therefore, the traveling thrust of the transport vehicle A is (1 / 3)V×(0.5 to 0.6)=(1 / 6 to 1 / 5)V.

[0074] The running resistance of transport vehicle A is total load V ÷ total 6 wheels × 4 swivel wheels × 0.1 = (1 / 15)V.

[0075] From the above, the traveling thrust of transport vehicle A is (1 / 6 to 1 / 5) ÷ (1 / 15) times, or 2.5 to 3 times, the traveling resistance of transport vehicle A. Therefore, regardless of whether there is a load on lift table T (Fig. 1), drive wheels 9 and 10 can transmit the driving force without slipping on the road surface G. If the load is distributed evenly or approximately evenly across all six wheels, the load on two drive wheels will be smaller than the load on all four swivel wheels, but it can be seen that the two drive wheels can transmit the necessary driving force to the road surface G.

[0076] 2 and 9, which has six wheels, namely, drive wheels 9 and 10 and swivel wheels 4 to 7, differs from the transporter 10 of Patent Document 1 in that, as described above, it has a left-right frame body 1 and front-rear frame bodies 2 and 3. An intermediate position between the swivel wheels 4 and 5 on the left-right frame body 1 is supported so as to be swingable about the front-rear axis Y1 with respect to the base N. An intermediate position between the drive wheel 9 and swivel wheel 6 on the front-rear frame body 2 is supported so as to be swingable about the left-right axis X2 and the front-rear axis Y2 with respect to the base N, and an intermediate position between the drive wheel 10 and swivel wheel 7 on the front-rear frame body 3 is supported so as to be swingable about the left-right axis X3 and the front-rear axis Y3 with respect to the base N.

[0077] Due to this structure, the transport vehicle A can travel on the road surface G with none of the six wheels floating above the road surface G and ensuring contact with the ground. Therefore, in Figure 19, by making U1 = U2 = U3 or U1 ≒ U2 ≒ U3, the transport vehicle A can travel while applying the load evenly or approximately evenly to the six wheels.

[0078] In the past, due to the influence of road undulations, for example, the entire load could be borne by just two diagonal wheels of the swivel wheels, making it necessary to install swivel wheels with a large allowable load. In contrast, the configuration of the transport vehicle A of the present invention, which can distribute the load evenly or approximately evenly across all six wheels, reduces the load on the swivel wheels 4 to 7 and prevents excessive load from being placed on the drive wheels 9 and 10. Therefore, the swivel wheels 4 to 7 and the drive wheels 9 and 10 can both be designed with the minimum allowable load required, thereby reducing wheel costs.

[0079] The above description of the embodiments is given by way of example only and is not intended to be limiting, and various improvements and modifications can be made without departing from the scope of the present invention. [Explanation of symbols]

[0080] 1 Left and right frame body 2,3 Front-rear frame body 4,5,6,7,8 swivel wheels 4A,5A,6A,7A Vertical support shaft 9,10 Drive wheels 9A, 10A Rotational axis A transport vehicle B Back C. Left-right length of the frame body D Left and right distance between the front and rear frame bodies E Elastic body F forward G road surface H1 First hinge H2 Second hinge I Inclined surface J step K Rotation direction in spin turn L left M1, M2 drive unit N base O Vertical axis P Spherical curved surface Q1, Q2, Q3 Cylindrical curved surface R Right side S1,S2 space T Height-Adjustable Table U1, U2, U3 Distance in the forward and backward directions W1 1st wheel section W2 Second wheel section W3 3rd wheel section X1,X2,X3 Left and right axis Y1,Y2,Y3 Anteroposterior axis

Claims

1. A transport vehicle equipped with left and right drive wheels, a first wheel unit located at a front end or a rear end of a base of the transport vehicle; a second wheel unit and a third wheel unit, which are independent and located on the left and right sides rearward or forward of the first wheel unit; The first wheel portion is a left-right frame body extending in the left-right direction; a pair of swivel wheels that are driven wheels and are arranged on the left and right sides of the left-right frame body, an intermediate position between the left and right swivel wheels of the left-right frame body is supported so as to be swingable about a front-rear axis relative to the base; The second wheel portion and the third wheel portion are a front-rear frame body extending in the front-rear direction; The drive wheels are disposed at the front or rear of the longitudinal frame body; and a swivel wheel that is a driven wheel and is arranged at the rear or front of the longitudinal frame body, The longitudinal frame body is supported at an intermediate position between the drive wheel and the swivel wheel so as to be swingable about a left-right axis and a longitudinal axis relative to the base. Transport vehicle.

2. A transport vehicle equipped with left and right drive wheels, a first wheel unit located at a front end or a rear end of a base of the transport vehicle; a second wheel unit and a third wheel unit, which are independent and located on the left and right sides rearward or forward of the first wheel unit; The first wheel portion is One or more swivel wheels are driven wheels and are located at the center of the base in the left-right direction, The second wheel portion and the third wheel portion are a front-rear frame body extending in the front-rear direction; The drive wheels are disposed at the front or rear of the longitudinal frame body; and a swivel wheel that is a driven wheel and is arranged at the rear or front of the longitudinal frame body, The longitudinal frame body is supported at an intermediate position between the drive wheel and the swivel wheel so as to be swingable about a left-right axis and a longitudinal axis relative to the base. Transport vehicle.

3. an intermediate position between the left swivel wheel and the right swivel wheel in the left-right frame body is further supported to be swingable about a left-right axis relative to the base; The transport vehicle according to claim 1 .

4. The swivel wheel of the first wheel unit is supported so as to be swingable around a left-right axis relative to the base. The transport vehicle according to claim 2 .

5. The mechanism for supporting the intermediate position between the drive wheel and the swivel wheel in the longitudinal frame body so as to be swingable about a left-right axis and a longitudinal axis relative to the base includes: a first hinge that swings about a left-right axis and a second hinge that swings about a front-rear axis, the first hinge and the second hinge being provided between the base and the front-rear frame body; The transport vehicle according to claim 1 or 2.

6. The mechanism for supporting the intermediate position between the drive wheel and the swivel wheel in the longitudinal frame body so as to be swingable about a left-right axis and a longitudinal axis relative to the base includes: an elastic body provided between the base and the front-rear direction frame body; The transport vehicle according to claim 1 or 2.

7. The length of the left-right frame body in the left-right direction is smaller than the distance between the left and right front-rear frame bodies in the left-right direction. The transport vehicle according to claim 1 or 3.

8. a distance in the front-rear direction between a rotation center axis of the drive wheel of the second wheel section and a vertical support axis of the swivel wheel of the second wheel section; The distance in the front-rear direction between the rotation center axis of the drive wheel of the third wheel unit and the vertical support axis of the swivel wheel of the third wheel unit, and The distance in the front-rear direction between the rotation center axis of the driving wheel or the vertical support axis of the swivel wheel of the driving wheel or the swivel wheel that is closest to the first wheel section in the second wheel section and the third wheel section, and the vertical support axis of the swivel wheel of the first wheel section. are identical or substantially identical, The longitudinal frame body is supported at a center or a vicinity of the center in the longitudinal direction between the rotation center axis of the drive wheel and the vertical support axis of the swivel wheel so as to be swingable about a left-right axis and a longitudinal axis relative to the base. A transport vehicle according to any one of claims 1, 3, 5, 6 and 7.

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