Shopping cart

Abstract

Without using training wheels, have the front wheels go over the obstacle. [Solution] The carry cart CC comprises wheels (front wheels 32 and rear wheels) that roll on the road surface 10, and a cart body 19 positioned above the contact points of the wheels with the road surface 10, on which the transported object C1 is placed. The front wheels 32 are supported by the cart body 19 via a link member 37 and an arm 41, and roll by rotation around the front axle 33. The arm body 42 of the arm 41 supports the front axle 33 and is rotatably supported by a link shaft 40 relative to the link body 39 behind the front axle 33. Behind the arm 41, an elastic part 55 is positioned that elastically deforms as the arm 41 rotates upward around the link shaft 40. With both the front wheels 32 and the rear wheels in contact with the same horizontal surface as the road surface 10, the link shaft 40 is positioned at the same position as the front axle 33 in the vertical direction, or at a higher position.

Description

Technical Field

[0001] The present invention relates to a carrier cart that includes wheels that roll on a road surface by rotating around an axle, and travels by the rolling of the wheels.

Background Art

[0002] In the field of carrier carts, various structures have been proposed for allowing wheels to overcome convex steps. For example, in the walking assist device described in Patent Document 1, a main wheel corresponding to a front wheel is provided, and an auxiliary wheel is provided in front of the main wheel in the traveling direction. The ground contact surface of the auxiliary wheel is set above the ground contact surface of the main wheel. A link mechanism is interposed between the auxiliary wheel and the main wheel. When the main wheel contacts a step, it is moved upward and rearward in the traveling direction. By this movement, the impact when the main wheel contacts the step is alleviated. Further, the movement of the main wheel is transmitted to the auxiliary wheel via the link mechanism, and the auxiliary wheel is rotated downward. Since the auxiliary wheel contacts the top surface of the step and presses the top surface, forward falling of the walking assist device is suppressed.

[0003] <00并将其发送到服务器端进行处理。当服务器端处理完成后,它会将结果返回给客户端。然后,客户端可以根据接收到的结果进行相应的操作,例如显示处理结果或进行进一步的处理。0012> When the main wheel gets over the step, the auxiliary wheel is rotated upward by an elastic body and returns to its original position. The walking assist device returns to the same posture as before getting over the step.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technique described in Patent Document 1 above, an auxiliary wheel is required to allow the main wheel (front wheel) to get over a step. However, there is a demand for a carrier cart that can allow the front wheel to get over a step without using such an auxiliary wheel. [Means for solving the problem]

[0006] A carry cart to solve the above problems comprises wheels that roll on the road surface, and a cart body positioned above the point where the wheels make contact with the road surface and on which the transported goods are placed, wherein the wheels are supported by the cart body via link members and arms and are front wheels that roll by rotation around the front axle, and rear wheels that are supported by the cart body behind the front wheels in the direction of travel and are rear wheels that roll by rotation around the rear axle, and the carry cart travels forward in the direction of travel by the rolling of each wheel, wherein the link members are attached to the cart body, and A carry cart having a link body portion located behind the front axle in the direction of travel, the arm supporting the front axle and having an arm body portion rotatably supported by a link shaft relative to the link body portion at the rear of the front axle in the direction of travel, and further having an elastic portion located behind the arm in the direction of travel that is elastically deformed as the arm rotates upward around the link shaft, and with both the front and rear wheels in contact with the same horizontal surface as the road surface, the link shaft is positioned at the same position as the front axle in the vertical direction, or higher than the front axle. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 shows an embodiment of a carry cart and is a partial side cross-sectional view of the front wheel support mechanism. [Figure 2] Figure 2 is a side view of the carry cart in the above embodiment, in which the front wheels are in contact with the rear corner of the step. [Figure 3] Figure 3 is a perspective view of the carry cart in the above embodiment. [Figure 4] Figure 4 is a bottom view of the carry cart in the above embodiment. [Figure 5] Figure 5 is a partial perspective view showing an enlarged view of the support mechanism in Figure 3. [Figure 6] Figure 6 is an exploded perspective view showing the components of the support mechanism in Figure 3, disassembled. [Figure 7] Figure 7 is a magnified partial side view showing the support mechanism in Figure 2. [Figure 8] Figure 8 is a partial side view showing the mounting state of the elastic part in the support mechanism of Figure 7. [Figure 9] Figure 9 is a partial side view of the carry cart in the above embodiment, showing the front wheels being lifted. [Figure 10] Figure 10 is a partial side view of the carry cart in the above embodiment, in which the front wheels roll along the top surface of a step. [Figure 11] Figure 11 is an explanatory diagram illustrating an example of the positional relationship between the front axle, link shaft, coupling, etc. [Figure 12] Figure 12 is an explanatory diagram illustrating another example of the positional relationship between the front axle, link shaft, coupling, etc. [Figure 13] Figure 13 is a schematic diagram illustrating an example of the positional relationship between the front axle, link shaft, coupling, etc. [Figure 14] Figure 14 is a schematic diagram illustrating another example of the positional relationship between the front axle, link shaft, coupling, etc. [Figure 15] Figure 15 is a characteristic diagram showing the relationship between load and elastic deformation for the elastic part. [Modes for carrying out the invention]

[0008] Below, one embodiment of the carry cart will be described with reference to the drawings. As shown in Figure 2, the carry cart CC comprises a plurality of wheels that roll on the road surface 10 and a cart body 19. The cart body 19 comprises a loading platform 20 on which the items to be transported C1, such as luggage, are placed, and a handle shaft 30 connected to the loading platform 20 and gripped and operated by the user of the carry cart CC.

[0009] The carrier cart CC travels forward in the forward direction due to the rolling of each wheel. In FIGS. 1, 2, 4, and 7 to 10, the forward direction is the direction from the right to the left in each figure, and the front in the forward direction is the left side in each figure.

[0010] In the following description, the forward direction of the carrier cart CC is taken as the front, and the reverse direction is taken as the rear for explanation. Also, the up-and-down direction means the up-and-down direction of the carrier cart CC, and the left-and-right direction is the direction orthogonal to both the forward direction and the up-and-down direction. The left-and-right direction is the width direction of the carrier cart CC and is assumed to be the same as the left-and-right direction when the carrier cart CC is moving forward.

[0011] <Road surface 10> The road surface 10 on which the carrier cart CC travels has a convex step 12. Here, in order to distinguish the convex step 12 from the portion different from the step 12 on the road surface 10, the latter is referred to as the general road surface 11. Also, the upper surface of the step 12 is called the top surface 13, and the rear upper corner of the step 12 is called the rear corner 14. For the sake of simplicity of explanation, here it is assumed that both the general road surface 11 and the top surface 13 are constituted by horizontal planes.

[0012] The top surface 13 is constituted by, for example, the upper surface of a sidewalk. The general road surface 11 is constituted by, for example, the upper surface of a roadway. Next, each part constituting the carrier cart CC will be described.

[0013] <Loading platform 20> As shown in FIGS. 2 to 4, the loading platform 20 includes a loading platform main body portion 21 and attachment protrusions 23. The loading platform main body portion 21 has a bottomed box shape provided with a storage portion 22 having an opening 22a at the upper end. The conveyed object C1 can be put in and taken out through the opening 22a with respect to the storage portion 22. The attachment protrusions 23 are provided at an upper portion of the loading platform main body portion 21, at least at a location adjacent to the front of the opening 22a. In the present embodiment, in addition to the above location, the attachment protrusions 23 are also provided at locations adjacent to both left and right sides of the opening 22a at the upper portion of the loading platform main body portion 21.

[0014] Rear wheel support portions 24 are respectively fixed to both side portions of the loading platform main body portion 21 in the left - right direction. The two rear wheel support portions 24 are spaced apart from each other in the left - right direction. As shown in FIGS. 2 and 4, the lower portions of each of the rear wheel support portions 24 extend below the bottom surface 21a of the loading platform main body portion 21.

[0015] As shown in FIGS. 1, 3 and 5, among the attachment protrusions 23, a bearing portion 25 is fixed to a central portion in the left - right direction of the loading platform 20, which is a portion in front of the opening 22a. The bearing portion 25 includes a pair of bearing plate portions 26 and a connecting plate portion 27. With both the front wheel 32 and the rear wheel 34 grounded on the same horizontal plane as the road surface 10, each of the pair of bearing plate portions 26 is inclined with respect to the horizontal plane so that the front side is positioned higher. The connecting plate portion 27 is inclined with respect to the vertical plane so that the upper side is positioned more rearward. The connecting plate portion 27 connects the rear edge portions of the pair of bearing plate portions 26. And the connecting plate portion 27 is fastened to the attachment protrusion 23 by fastening members 28 such as bolts and nuts.

[0016] <Handle shaft 30> As shown in FIG. 2, the handle shaft 30 has a central axis line CL1 extending in a direction intersecting with the horizontal plane. In the present embodiment, the central axis line CL1 is inclined with respect to the vertical line VL so that the upper side is positioned more rearward. Here, the angle formed by the central axis line CL1 with respect to the vertical line VL is defined as the caster angle θ1. In the present embodiment, as an example, the caster angle θ1 is set to 20°, but it is not limited thereto.

[0017] As shown in Figures 1 and 5, the lower part of the handle shaft 30 is inserted through the pair of bearing plate portions 26 described above. The lower end of the handle shaft 30 protrudes below the lower bearing plate portion 26. The handle shaft 30 is supported by the bearing portion 25 at both bearing plate portions 26. The handle shaft 30 constitutes the steering shaft and is capable of rotating about the central axis CL1.

[0018] The handle shaft 30 is connected to the front upper end of the loading platform 20 via the bearing portion 25 and the fastening member 28. As shown in Figure 2, the carry cart CC is attached to the upper end of the handle shaft 30 and has a grip portion 31 for the user of the carry cart CC to grasp. The user can rotate the handle shaft 30 around the central axis CL1 by changing the orientation of the grip portion 31.

[0019] <Multiple wheels> As shown in Figures 2 and 4, the multiple wheels consist of a single front wheel 32 and a pair of rear wheels 34.

[0020] The front wheel 32 is supported on the handle shaft 30 by a support mechanism M1 located below the fastening member 28. The front wheel 32 is a drive wheel that is rotated around the front axle 33 by a motor (not shown) as a power source, and provides propulsion to the carry cart CC for driving. The motor is supplied with power from a battery (not shown) mounted on the cargo bed 20, etc. As the motor, for example, an electric motor of the type that is positioned inside or near the wheel of the front wheel 32 and transmits power to the front wheel 32 to directly rotate the front wheel 32, a so-called in-wheel motor, may be used. In this embodiment, the front wheel 32 uses the above-mentioned in-wheel motor.

[0021] As shown in Figures 5 and 6, the front wheel 32 and the front axle 33 are constructed as a single integrated part. Both ends of the front axle 33 protrude from the front wheel 32 to both sides in the direction in which the front axle 33 extends.

[0022] As shown in Figures 2 to 4, each rear wheel 34 is rotatably supported on the rear axle 35 with respect to the portion of the rear wheel support 24 that is below the bottom surface 21a of the cargo bed body 21. Each rear wheel 34 rolls on the road surface 10 by rotating around the rear axle 35. Unlike the front wheels 32, both rear wheels 34 are driven wheels that do not generate driving force. Both rear wheels 34 have a wheel diameter (diameter) that is about the same as that of the front wheels 32.

[0023] As shown in Figures 2 and 4, the cargo bed 20 is positioned above the contact points of the front wheels 32 and rear wheels 34 with the road surface 10, for example, a general road surface 11. The bottom surface 21a of the cargo bed 20 is located higher than the lowest point of the front wheels 32 and rear wheels 34, and lower than the highest point of the respective wheels.

[0024] The support mechanism M1 comprises a link member 37, an arm 41, a bracket 51, and an elastic part 55. <Link member 37> As described above, the lower end of the handle shaft 30 protrudes below the lower bearing plate portion 26, as shown in Figures 1 and 5. The link member 37 is fastened to the lower end of the handle shaft 30 by fastening members 38 such as bolts so that it can rotate integrally with the handle shaft 30.

[0025] As shown in Figures 5 and 6, the link member 37 has a pair of link body portions 39 extending vertically, located behind the front axle 33. The pair of link body portions 39 are spaced apart from each other in the direction in which the front axle 33 extends. The distance between the two link body portions 39 is slightly greater than the dimension of the front wheel 32 in the direction in which the front axle 33 extends.

[0026] <Arm 41> The arm 41 comprises a pair of arm body portions 42 and an arm mounting portion 46. Each arm body portion 42 comprises a front plate portion 43 and a rear plate portion 45 adjacent to the rear side of the front plate portion 43. The pair of arm body portions 42 are positioned on both sides of the front wheel 32 in the direction in which the front axle 33 extends.

[0027] As shown in Figures 2, 6, and 7, when the front wheels 32 and both rear wheels 34 are in contact with a horizontal surface, such as a general road surface 11, the front plate portion 43 of each arm body portion 42 is inclined with respect to the general road surface 11 such that it becomes lower towards the front. The rear plate portion 45 of each arm body portion 42 extends in the front-rear direction. The front plate portion 43 and rear plate portion 45 of each arm body portion 42 are bent so as to protrude diagonally forward and upward.

[0028] The arm 41 supports the front axle 33, thereby supporting the front wheel 32 to the link member 37. More specifically, each front plate portion 43 has a notch 44 that extends diagonally upward and backward from the front lower end of the front plate portion 43, with both the front wheel 32 and the rear wheel 34 in contact with the same horizontal surface as the road surface 10. That is, the notch 44 of each front plate portion 43 is inclined with respect to the horizontal and vertical planes so that it is located higher towards the rear. The portion of the front axle 33 that protrudes from the front wheel 32 is inserted into and supported in the notch 44 of each front plate portion 43. The arm mounting portion 46 connects the rear edges of a pair of arm body portions 42 behind the front wheel 32.

[0029] The arm 41, configured as described above, is positioned between a pair of link body portions 39. More specifically, each arm body portion 42 is positioned adjacent to the inside of the link body portion 39 in the direction in which the front axle 33 extends.

[0030] Each arm body 42 is supported by a link shaft 40 so as to be able to rotate vertically with respect to a link body 39 adjacent to it on the outside in the direction in which the front axle 33 extends, located behind the front wheel 32.

[0031] <Bracket 51> As shown in Figures 1, 2, and 6, the bracket 51 comprises a flat bracket body portion 52 and a pair of mounting plate portions 53. The pair of mounting plate portions 53 are adjacent to the outside of the link body portion 39 in the direction in which the front axle 33 extends (see Figure 5). The bracket body portion 52 is located behind the pair of link body portions 39 and behind the arm mounting portion 46. The bracket body portion 52 connects the rear edges of the pair of mounting plate portions 53. The bracket body portion 52 is inclined with respect to the vertical line VL such that, when both the front wheel 32 and the rear wheel 34 are in contact with the same horizontal surface as the road surface 10, the upper part is located further back. Each mounting plate portion 53 is fastened to the link body portion 39 adjacent to the inside of the mounting plate portion 53 in the direction in which the front axle 33 extends by fastening members 54 such as bolts. In addition, each mounting plate portion 53 is connected to the adjacent link body portion 39 by the link shaft 40.

[0032] <Elastic part 55> As shown in Figures 1 and 6, the elastic portion 55 comprises an elastic main body portion 56, a first attachment portion 57, and a second attachment portion 58. The elastic portion 55 is positioned between the arm mounting portion 46 and the bracket main body portion 52.

[0033] The elastic body portion 56 is formed from rubber so as to be elastically deformable and has a central axis CL2. The elastic body portion 56 is bowl-shaped with an open rear surface. The outer surface of the elastic body portion 56 has a hemispherical curved surface 56a that curves forward. The inner surface of the elastic body portion 56 has a hemispherical curved surface 56b that curves forward and concave. The elastic body portion 56 has the characteristic that the amount of elastic deformation increases as the load applied to it increases.

[0034] The first attachment portion 57 and the second attachment portion 58 are made of a material that is less elastically deformable than the elastic main body portion 56, such as metal, and have higher strength than the elastic main body portion 56. The first attachment portion 57 is attached to the front end of the elastic main body portion 56, and the second attachment portion 58 is attached to the rear end of the elastic main body portion 56. In other words, the first attachment portion 57 and the second attachment portion 58 are connected by the elastic main body portion 56.

[0035] The elastic portion 55 is fastened to the arm mounting portion 46 by fastening members 61 such as bolts at the first attachment portion 57. The elastic portion 55 is fastened to the bracket body portion 52 by fastening members 62 such as bolts at the second attachment portion 58.

[0036] The elastic body portion 56 of the elastic portion 55 configured in this way is compressed and elastically deformed as the arm 41 rotates upward around the link shaft 40. Furthermore, as shown in Figures 2 and 7, with both the front wheel 32 and the rear wheel 34 in contact with the same horizontal surface as the road surface 10, the link shaft 40 is positioned at the same position as the front axle 33 in the vertical direction, or at a higher position than the front axle 33. In this embodiment, the link shaft 40 is positioned at the same position as the front axle 33 in the vertical direction.

[0037] Furthermore, as shown in Figure 8, the elastic part 55 is positioned inclined with respect to the horizontal plane such that its central axis CL2 is lower towards the rear. In other words, the second attachment portion 58 of the elastic part 55 is inclined with respect to the vertical line VL such that it is located further back towards the top. Here, the angle that the second attachment portion 58 makes with respect to the vertical line VL is defined as the elastic part mounting angle θ3. The unit of the elastic part mounting angle θ3 is degrees [deg]. The elastic part mounting angle θ3 is set to such a magnitude that the direction of the force acting from the arm 41 to the elastic part 55 when the arm 41 rotates upward around the link axis 40 is aligned with the central axis CL2. The elastic part mounting angle θ3 is preferably set to, for example, 5 to 15 degrees. In this embodiment, the elastic part mounting angle θ3 is set to 10 degrees.

[0038] As described above, the front wheel 32 is supported by the support mechanism M1 on the handle shaft 30 and attached to the cart body 19. Therefore, as shown in Figures 2 and 8, when the handle shaft 30 rotates around the central axis CL1 in response to the operation of the gripping part 31, the direction in which the front axle 33 extends is changed in response to that rotation. The rotation of the front wheel 32 changes the direction of travel of the carry cart CC.

[0039] <Operation of this embodiment> In describing the operation of this embodiment, we will assume that the object to be transported C1 is placed on the loading platform 20 of the carry cart CC, as shown in Figure 2.

[0040] When the front wheels 32 and both rear wheels 34 are in contact with a general road surface 11 which is a horizontal surface, the bottom surface 21a of the cargo bed 20 becomes horizontal. As shown by arrow A in Figure 2, when the front wheel 32 is rotated forward and downward by the motor, a thrust force is generated in the front wheel 32 that causes the carry cart CC to move forward. This thrust force is transmitted to both rear wheels 34 via the arm 41, link member 37, handle shaft 30, loading platform 20, etc. Pulled forward by the transmitted thrust force, both rear wheels 34 rotate forward and downward in conjunction with the front wheel 32, as shown by arrow B.

[0041] The front wheels 32 and both rear wheels 34 roll forward on the general road surface 11. The carry cart CC moves forward (self-propelled) along the general road surface 11 without tilting its bottom surface 21a. As shown in Figures 1 and 7, as the carry cart CC moves (self-propelled), the front wheels 32 make contact with the rear corner 14 of the step 12 from behind. This contact causes a force to act from the front wheels 32 diagonally forward and downward on the step 12. In particular, since the transported object C1 is placed on the platform 20, the forward movement of the carry cart CC is restricted by the contact of the front wheels 32 with the step 12, causing the transported object C1 to try to move forward due to inertia. Therefore, the diagonal forward and downward force is more likely to act from the front wheels 32 on the corner 14. On the other hand, as a reaction force to the above force, a reaction force RF1 acts on the front wheels 32 diagonally rearward and upward from the corner 14. This reaction force RF1 is a force that tries to push back the front wheels 32 that are trying to roll forward.

[0042] Here, assuming that the carry cart CC does not have any features to make it easier for the front wheels 32 to overcome the step 12, the front wheels 32 will have difficulty overcoming the step 12. Furthermore, as the step 12 gets higher, it becomes more difficult for the front wheels 32 to overcome it.

[0043] In this embodiment, the arm 41 is supported by the link shaft 40 so as to be rotatable in the vertical direction on the link member 37. Due to the reaction force RF1, the arm 41 attempts to rotate upward around the link shaft 40, compressing and elastically deforming the elastic portion 55 downward and rearward. As a result, an upward force F1 acts on the front wheel 32.

[0044] Furthermore, as described above, when the front wheel 32, which rotates forward and downward, comes into contact with the corner 14 of the step 12, a force acts from the front wheel 32 on the corner 14 diagonally backward and downward. As shown in Figure 9, a reaction force RF2 of this force acts from the corner 14 on the front wheel 32. As components of this reaction force RF2, an upward component Fa and a forward component Fb act on the front wheel 32.

[0045] Then, the component force Fa is added to the upward force F1 acting on the front wheel 32 as the arm 41 rotates, causing the front wheel 32 to lift. In contrast, both rear wheels 34 remain in contact with the general road surface 11. Therefore, as shown in Figure 9, the bottom surface 21a of the cargo bed 20 becomes inclined with respect to the horizontal plane, becoming lower towards the rear.

[0046] Here, the distance from the lowest point of the lifted front wheel 32 to the top surface 13 of the step 12 is defined as the overlap (lap allowance) Δh. As the lifting increases, the overlap Δh decreases. As the overlap Δh decreases, the force required for the front wheel 32 to overcome the step 12 decreases. Unlike conventional carry carts, the front wheel 32 can easily overcome the step 12 without the use of auxiliary wheels.

[0047] As shown in Figure 10, when the front wheel 32 rides onto the step 12, that is, when it passes the corner 14, the reaction force RF1 (see Figure 7) ceases to act on the front wheel 32. Due to the elastic restoring force of the elastic part 55, the arm 41 attempts to rotate downward around the link shaft 40, as indicated by arrow C in Figure 10, and the front wheel 32 returns to the same state as before it rode onto the step 12.

[0048] The front wheels 32 are in contact with the top surface 13 of the step 12, while both rear wheels 34 are still in contact with the general road surface 11. The front wheels 32 are positioned higher than both rear wheels 34. The bottom surface 21a of the cargo bed 20 maintains an inclined state with respect to the horizontal plane, becoming lower towards the rear.

[0049] As the front wheels 32 rotate forward and downward as indicated by arrow A, and both rear wheels 34 rotate forward and downward as indicated by arrow B, the carry cart CC moves forward with the bottom surface 21a of the loading platform 20 tilted relative to the horizontal plane as described above. As the carry cart CC moves, although not shown in the figures, both rear wheels 34 come into contact with the rear corner 14 of the step 12 from behind. At this time, unlike when the front wheels 32 come into contact with the step 12, as described above, a force acts on the rear wheels 34 diagonally forward and upward. This is because, as shown in Figure 2, when the front wheels 32 come into contact with the corner 14 of the step 12, the bottom surface 21a of the loading platform 20 is not tilted relative to the horizontal plane. In contrast, when both rear wheels 34 come into contact with the corner 14, the bottom surface 21a of the loading platform 20 is tilted relative to the horizontal plane so that it is lower towards the rear.

[0050] Therefore, both rear wheels 34 can overcome the step 12 with less force than the front wheels 32 can overcome the step 12. In addition, the propulsive force generated by the rotational drive of the front wheels 32 exerts a force on both rear wheels 34 that pulls them forward. Due to this force, both rear wheels 34 rotate forward and downward as indicated by arrow B in Figure 10, and when they overcome the step 12, although not shown in the figure, both the front wheels 32 and both rear wheels 34 come into contact with the top surface 13 of the step 12.

[0051] Furthermore, if the front wheels 32 come into contact with a new protruding step while the carry cart CC is continuing to travel on the top surface 13, the front wheels 32 and both rear wheels 34 will overcome this new step in the same manner as when overcoming the step 12 from the general road surface 11.

[0052] By the way, when the front wheels 32 and both rear wheels 34 are in contact with the same horizontal surface, such as a general road surface 11, as the road surface 10, if the link shaft 40 is located lower than the front axle 33 (see Figure 12), the following phenomenon may occur. That is, the lower surface of the part of the link member 37, arm 41, and bracket 51 shown in Figure 5 that is below the part through which the link shaft 40 is inserted is located at the lowest point of the support mechanism M1. To put it another way, the height of this lower surface is the minimum ground clearance of the carry cart CC. The minimum ground clearance is the height from the ground (road surface 10) of the lowest part of the parts, members, etc., located between the front axle 33 and both rear axles 35 of the carry cart CC, as shown in Figure 2. Furthermore, when the front wheel 32 crosses a step, the elastic part 55 is elastically deformed, causing the front wheel 32 to be lifted. At this time, the lower surface of the part of the link member 37, arm 41, and bracket 51 below the part through which the link shaft 40 is inserted may interfere with the top surface 13.

[0053] In this embodiment, as shown in Figures 7 and 11, when the front wheel 32 and rear wheel 34 are in contact with the same horizontal surface as the road surface 10, the link shaft 40 is at the same height as the front axle 33. In this case, the minimum ground clearance is higher than the minimum ground clearance when the link shaft 40 is lower than the front axle 33 (see Figure 12). Therefore, when the front wheel 32 goes over a step, the elastic part 55 is elastically deformed and the front wheel 32 is lifted, making it less likely for the link member 37, arm 41 and bracket 51 to interfere with the top surface 13 of the step 12.

[0054] As shown in Figure 12, the vertical deviation between the position of the link shaft 40 and the position of the front axle 33 is defined as the height difference ΔD1. The unit is [mm]. If the link shaft 40 is higher than the front axle 33, the height difference ΔD1 will be a positive (+) value. Conversely, if the link shaft 40 is lower than the front axle 33, the height difference ΔD1 will be a negative (-) value. In this embodiment, where the link shaft 40 is at the same height as the front axle 33, the height difference ΔD1 is 0 mm.

[0055] Furthermore, the various characteristics of the carry cart CC will differ depending on the dimensional and positional relationships of the front axle 33, arm 41, link member 37, etc. These characteristics include the ability to overcome obstacles.

[0056] As shown in Figures 11 and 12, the dimensional relationships include, in addition to the height difference ΔD1, the distance between the elastic parts of the link shafts L1, the distance between the axles of the link shafts L2, the lever ratio R, and the link angle θ4. The distance between the elastic parts of the link shafts L1 is the distance between the link shaft 40 and the connecting portion (hereinafter referred to as the connecting portion 47) of the arm 41 to the elastic part 55 by the fastening member 61. The distance between the axles of the link shafts L2 is the distance between the link shaft 40 and the front axle 33. The lever ratio R is the ratio of the distance between the axles of the link shafts L2 to the distance between the elastic parts of the link shafts L1 (L2 / L1). The link angle θ4 is the angle that a virtual line passing through the link shaft 40 and the connecting portion 47 makes with a virtual line passing through the link shaft 40 and the front axle 33.

[0057] Figure 11 and Figure 12 differ in the following respects. • The distance L2 between the link axle and the axle in Figure 12 is longer than the distance L2 between the link axle and the axle in Figure 11.

[0058] In Figure 11, the link shaft 40 is at the same height as the front axle 33, and the height difference ΔD1 is 0 mm. In contrast, in Figure 12, the link shaft 40 is lower than the front axle 33, so the height difference ΔD1 is a negative value (-).

[0059] • The link angle θ4 in Figure 12 is smaller than the link angle θ4 in Figure 11. Figures 13 and 14 schematically show the positional relationship between the front axle 33, the link shaft 40, and the connecting portion 47.

[0060] In Figure 13, the distance L2 between link axles is set to the same value as the distance L1 between elastic parts of link axles. The lever ratio R is 1.0. The angle that the imaginary line passing through the front axle 33 and the connecting part 47 makes with respect to the imaginary line passing through the same front axle 33 and the link axle 40 is 45 degrees (°).

[0061] In contrast, in Figure 14, the distance L2 between link axles is set to a value obtained by multiplying the distance L1 between elastic parts of the link axles by √3. The lever ratio R is 1.7. The angle that the imaginary line passing through the front axle 33 and the connecting part 47 makes with the imaginary line passing through the same front axle 33 and the link axle 40 is 30 degrees (°).

[0062] Note that the lever ratio R shown in Figures 13 and 14 is merely an example, and other values ​​may be set. As shown in Figure 1, when the front wheel 32 contacts the corner 14 of the step 12, a force F1 (load) is applied to the front wheel 32 that attempts to lift it, as previously described. Also, as shown in Figures 13 and 14, the upward rotation of the arm 41 around the link shaft 40 causes a force F2 to act on the elastic part 55 through the connecting part 47, causing the elastic body part 56 to undergo elastic deformation. In Figures 13 and 14, the elastic body part 56 before elastic deformation is shown by a solid line, and the elastic body part 56 after elastic deformation is shown by a dashed line.

[0063] When the arm 41 is rotated upward around the link shaft 40 by the force F1 described above, the front wheel 32 and front axle 33 are lifted by, for example, 1.3 mm, as shown by the dashed line in Figure 13. As a result, the elastic body 56 is elastically deformed by the same amount, 1.3 mm. This is because the load applied to the elastic part 55 is the same as the load applied to the front wheel 32 and front axle 33.

[0064] In contrast, in Figure 14, when a force F1 of the same magnitude as in Figure 13 is applied to the front wheel 32 and front axle 33, the arm 41 rotates upward around the link axis 40. As shown by the dashed line in Figure 14, the front wheel 32 and front axle 33 are lifted by 3.8 mm, and the elastic body 56 is elastically deformed by 2.2 mm. This is because a load √3 times greater than the load applied to the front wheel 32 and front axle 33 is applied to the elastic part 55. As the amount of elastic deformation of the elastic body 56 increases, the front wheel 32 is lifted more.

[0065] Here, as shown in Figure 12, when the link shaft 40 is positioned lower than the front axle 33, if the distance L2 between the link shaft and the axle increases, the load applied to the elastic part 55 when crossing a step increases, and the amount the front wheel 32 is lifted increases. The link member 37, arm 41 and bracket 51 are more likely to interfere with the top surface 13 of the step 12.

[0066] In contrast, when the link shaft 40 is positioned at the same height as the front axle 33, or at a higher position, increasing the distance L2 between the link shaft and the axle makes interference with the link member 37, the arm 41, and the top surface 13 of the bracket 51 less likely, making it easier for the front wheel 32 to overcome the step 12.

[0067] Furthermore, the longitudinal dimensions of the support mechanism M1, that is, the overall longitudinal dimensions of the link member 37, arm 41, bracket 51, and elastic part 55, are affected by the distance L2 between the link axles. The shorter the distance L2 between the link axles, the smaller the longitudinal dimensions become, and thus the more compact the support mechanism M1 becomes in the longitudinal direction.

[0068] Therefore, it is assumed that the link shaft 40 is positioned at the same height as the front axle 33, or at a higher position. Based on this assumption, it is preferable to determine the distance L1 between the elastic parts of the link shaft, the distance L2 between the link shafts and axles, the link angle θ4, etc., while considering the ease with which the front wheel 32 can overcome the step 12, the dimensions in the longitudinal direction, etc.

[0069] Furthermore, as shown in Table 1, nine combinations were set for multiple types of height difference ΔD1, multiple types of link shaft elastic part distance L1, multiple types of link shaft axle distance L2, and multiple types of link angle θ4. These combinations consist of eight examples (Examples 1-8) and one comparative example. In Examples 1-8, three types of height difference ΔD1 were set in the range of -10mm to 10mm, while in the comparative example, the height difference ΔD1 was set to -4.5mm. In Examples 1-8, seven types of lever ratio R were set in the range of 2.0 to 5.5, while in the comparative example, the lever ratio R was set to 3.0.

[0070] Then, for each combination, we evaluated whether the front wheels 32 could overcome the step 12. In this process, we used an elastic part 55 having the characteristics shown in Figure 15 in relation to the input load and the amount of elastic deformation. As the elastic part 55, we used one with a spring constant of 60 N / mm, that is, an elastic part 55 that requires a load of 60 Newtons (N) to cause an elastic deformation of 1 mm.

[0071] [Table 1]

[0072] In all examples and comparative examples, it was confirmed that the front wheel 32 could overcome the step 12. It was also confirmed that the front wheel 32 could overcome the step 12 regardless of whether the lever ratio R was set to 2.0 or 5.5. However, Table 1 shows the measurement results when the lever ratio R was set in the range of 2.0 to 5.5. Therefore, this does not negate the possibility of setting the lever ratio R to less than 2.0 or to a value greater than 5.5.

[0073] Furthermore, in Examples 2, 4, 6 and Comparative Examples where the height difference ΔD1 is negative (-), the lower surface of the link member 37, arm 41, and bracket 51 through which the link shaft 40 is inserted is more likely to interfere with the top surface 13 of the step 12.

[0074] In this embodiment, as shown in Figures 1, 6, and 8, the outer surface of the elastic body portion 56 of the elastic part 55 has a hemispherical curved surface 56a. As the arm 41 rotates, a load directed downward and rearward (see force F2 in Figures 13 and 14) is applied to the elastic part 55. When both the front wheel 32 and both rear wheels 34 are in contact with the same horizontal surface as the road surface 10, the central axis CL2 of the elastic body portion 56 is inclined with respect to the horizontal plane such that it is lower towards the rear. The second attachment portion 58 of the elastic part 55 is inclined with respect to the vertical line VL such that it is located further rearward towards the upper side. Therefore, a load is more easily applied from the arm 41 to the elastic body portion 56 in the direction along the central axis CL2 than when the central axis CL2 is not inclined with respect to the horizontal plane or when the second attachment portion 58 is not inclined with respect to the vertical line VL.

[0075] <Effects of this embodiment> (1) As shown in Figure 1, a link member 37 is attached to the handle shaft 30 of the cart body 19. An arm 41 that supports the front axle 33 is supported by the link shaft 40 so as to be able to rotate vertically relative to the link member 37. Behind the arm 41 is an elastic part 55 which is compressed and elastically deformed as the arm 41 rotates upward around the link shaft 40.

[0076] Therefore, as the front wheel 32 comes into contact with the corner 14 of the step 12, the reaction force RF1 directed diagonally upward and backward applied to the front wheel 32 from the corner 14 causes the elastic body 56 of the elastic part 55 to compressively deform, thereby allowing the arm 41 to rotate upward. An upward force F1 can be applied to the front wheel 32.

[0077] Furthermore, as shown by arrow A in Figure 9, when the front wheel 32, which rotates forward and downward, contacts the corner 14, a reaction force RF2 is applied from the corner 14 to the front wheel 32, directed diagonally forward and upward. The upward component force Fa of this reaction force RF2 can be applied to the front wheel 32.

[0078] The above-mentioned force F1 and component force Fa lift the front wheel 32, reducing the amount of force Δh required to move the front wheel 32 over the step 12. As a result, the front wheel 32 can move over the step 12 without the use of auxiliary wheels.

[0079] (2) In the case of a non-self-propelled carry cart that is pushed forward by the user, if the front wheels come into contact with a protruding step 12 and hinder its movement, the user lifts the front wheels of the carry cart. This operation makes it possible for the front wheels to overcome the step 12.

[0080] In contrast, with a self-propelled carry cart, the user does not perform any operations such as lifting the front wheels, as described above. In this embodiment, the front wheels 32 are driven by a motor to provide propulsion for movement. The configuration described in (1) above is adopted for the carry cart CC in which the front wheels 32 are the drive wheels. Specifically, the carry cart CC uses a link member 37, an arm 41, and an elastic part 55.

[0081] Therefore, although the carry cart CC is self-propelled and does not require user operation, it is possible to make the front wheels 32 overcome the step 12. Accordingly, the configuration described in (1) above is particularly useful for the carry cart CC of this embodiment, which has no means to overcome the step 12 other than by the driving force of the front wheels 32.

[0082] (3) As shown in Figure 2, with the front wheels 32 and both rear wheels 34 in contact with the same horizontal surface as the road surface 10, the link shaft 40 is positioned in the same position as the front axle 33 in the vertical direction, as shown in Figures 1 and 7.

[0083] Therefore, unlike the case where the link shaft 40 is lower than the front axle 33 (see Figure 12), when the front wheel 32 rides over a step, the lower surface of the part of the link member 37, arm 41, and bracket 51 below the insertion portion of the link shaft 40 can be prevented from interfering with the top surface 13.

[0084] (4) As shown in Figures 1 and 6, the elastic portion 55 is formed of rubber so as to be elastically deformable and comprises an elastic body portion 56 having a central axis CL2. The outer surface of the elastic body portion 56 has a hemispherical curved surface 56a that curves forward.

[0085] Therefore, even if the arm 41 rotates around the link shaft 40 and the direction of the load applied to the elastic part 55 (see force F2 in Figures 13 and 14) changes, the load is still likely to act on the elastic main body 56. Regardless of the change in the direction of the applied load, the elastic main body 56 is easily compressed and elastically deformed. This suppresses large changes in the biasing force of the elastic main body 56 due to changes in the direction of the applied load.

[0086] (5) As shown in Figures 1, 6 and 8, the elastic portion 55 is positioned inclined with respect to the horizontal plane such that the central axis CL2 of the elastic main body portion 56 is lower towards the rear. The second attachment portion 58 is positioned inclined with respect to the vertical line VL such that the upper part is located towards the rear.

[0087] Therefore, a load can be applied to the elastic part 55 from the arm 41, which rotates upward around the link shaft 40, in a direction along the central axis CL2. This allows the elastic part 55 to be elastically deformed more efficiently.

[0088] (6) As shown in Figure 2, the handle shaft 30 is inclined with respect to the vertical line VL such that the upper part is located further back. Therefore, when a load is applied to the gripping part 31, it is possible to suppress the transmission of that load to the elastic part 55 via the handle shaft 30, link member 37, etc.

[0089] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0090] (Matters concerning cargo bed 20) In Figure 2, the vertical position of the cargo bed 20 may be changed, provided that the front wheels 32 and both rear wheels 34 are positioned above the point of contact with the road surface 10, for example, a general road surface 11. For example, the bottom surface 21a of the cargo bed 20 may be positioned higher than the uppermost points of the front wheels 32 and the rear wheels 34.

[0091] (Matters concerning the handle shaft 30) • The central axis CL1 of the handle shaft 30 in Figure 2 may extend in the vertical direction. (Matters concerning wheels) The number of front wheels 32 may be changed to multiple. Also, the number of rear wheels 34 may be changed to 3 or more. Furthermore, if the number of front wheels 32 is changed to multiple, the number of rear wheels 34 may be changed to 1.

[0092] The front wheel 32 may be rotationally driven by a motor provided on the outside of the front wheel 32. The front wheels 32 may be driven by a power source other than the motor. The rear wheels 34 may be driven wheels that are rotationally driven by a power source, and the front wheels 32 may be driven wheels. In addition, the rear wheels 34 may be driven wheels that are rotationally driven by a power source, in addition to the front wheels 32.

[0093] The front wheel 32 and the rear wheel 34 may have different wheel diameters. (Matters concerning link shaft 40) With both the front wheels 32 and both rear wheels 34 in contact with the same horizontal surface as the road surface 10, the link shaft 40 may be positioned higher than the front axle 33 in the vertical direction. In this case as well, the same operation and effects as in the above embodiment, where it is positioned at the same position as the front axle 33 in the vertical direction, can be obtained.

[0094] (Matters concerning Arm 41) In Figures 5 and 6, the front plate portion 43 and the rear plate portion 45 of each arm body portion 42 do not necessarily have to be bent. Each arm body portion 42 may, for example, be in the shape of a triangular plate.

[0095] - If the front wheels 32 are not driven by a motor, the front axle 33 may be separated from the front wheels 32. In this case, bearing holes may be formed at the front end of each arm body portion 42 instead of the notches 44. Then, each portion of the front axle 33 that protrudes from the front wheels 32 to both sides in the direction in which the front axle 33 extends may be supported by the arm body portion 42 by being inserted into the bearing holes of each arm body portion 42. In order to insert each protruding portion of the front axle 33 from the front wheels 32 into the bearing holes of each arm body portion 42, the arm 41 may be divided into a pair of arm body portions 42.

[0096] (Matters concerning the elastic part 55) - As the elastic part 55, an elastic body part 56 may be used in which the outer surface of the elastic body part 56 has a hemispherical curved surface 56a, and the inner surface of the elastic body part 56 does not have a hemispherical curved surface 56b.

[0097] - The elastic portion 55 may be one in which the outer surface of the elastic main body portion 56 does not have a hemispherical curved surface 56a. In this case, the inner surface of the elastic main body portion 56 may or may not have a hemispherical curved surface 56b.

[0098] • A different elastic body than the one used in the above embodiment may be used as the elastic part 55. For example, a spring such as a coil spring or a leaf spring may be used as the elastic part 55. Alternatively, an elastic body other than a spring may be used as the elastic part 55.

[0099] (Other matters) The carry cart of the present invention may also be applied to a non-self-propelled carry cart. According to this modification, if the front wheels 32 come into contact with a step 12, the front wheels 32 can be made to overcome the step 12 without any operation by the user, such as lifting the front wheels 32. Users of the carry cart CC will find it easier to overcome the step 12 even if the front wheels 32 come into contact with the step 12, making the carry cart CC easier to use.

[0100] The carry cart CC may be equipped with a seat for the user to sit on and a shopping basket. The carry cart CC may also be equipped with a structure for attaching the shopping basket detachably. In addition, the carry cart CC may be equipped with a place to hang bags such as tote bags and purses.

[0101] The carry cart CC may be equipped with a braking mechanism to adjust the travel speed or stop the cart from moving. According to this modification, when the carry cart CC is in motion, the rotation speed of the front wheels 32 and the rear wheels 34 can be adjusted by applying braking force to at least one of them. In addition, the carry cart CC can be stopped from moving by stopping the rotation of at least one of the front wheels 32 and the rear wheels 34.

[0102] Furthermore, the carry cart CC may be equipped with a braking mechanism to keep the carry cart CC stationary when parked. In the case of a carry cart CC equipped with a seat, the carry cart CC may be equipped with a braking mechanism to keep the carry cart CC stationary when someone is sitting on the seat. [Explanation of Symbols]

[0103] 10…road surface 19... Cart body 32…Front wheel 33…Front axle 34...Rear wheel (wheel) 35…Rear axle 37…Link component 39...Link body 40... Link axis 41... Arm 42...Arm body 46... Arm mounting section 51…Bracket 52…Bracket body 55...Elastic part 56...Elastic main body 56a...Curved surface 57...First attachment part 58…Second attachment part C1…Object to be transported CC...Carry Cart CL2…Center axis line

Claims

1. It comprises wheels that roll on the road surface, and a cart body positioned above the point where the wheels make contact with the road surface, on which the object to be transported is placed. The cart comprises a front wheel supported on the cart body via a link member and an arm, which rolls by rotation around the front axle, and a rear wheel supported on the cart body behind the front wheel in the direction of travel, which rolls by rotation around the rear axle, and the cart moves forward in the direction of travel by the rolling of each wheel, The link member is attached to the cart body and has its link body located behind the front axle in the direction of travel. The arm supports the front axle and has an arm body that is rotatably supported by a link shaft relative to the link body, behind the front axle in the direction of travel. Furthermore, behind the arm in the direction of travel, an elastic part is positioned which is elastically deformed as the arm rotates upward around the link axis. A carry cart in which both the front and rear wheels are in contact with the same horizontal surface as the road surface, and the link shaft is positioned at the same position as the front axle in the vertical direction, or at a position higher than the front axle.

2. The elastic part is formed of rubber so as to be elastically deformable and comprises an elastic main body having a central axis, The outer surface of the elastic body portion has a hemispherical curved surface that curves forward in the direction of travel, The elastic portion is attached to the arm at its front end in the direction of travel. The carry cart according to claim 1, wherein the elastic portion is arranged in a state inclined with respect to the horizontal plane such that the central axis becomes lower towards the rear in the direction of travel.

3. The link body is further equipped with a bracket attached to it, The bracket has a bracket body portion located behind the arm in the direction of travel. The arm is located behind the front wheel in the direction of travel and further includes an arm mounting portion located in front of the bracket body. The elastic portion further comprises a first attachment portion that is attached to the arm at the arm mounting portion, and a second attachment portion that is attached to the bracket body portion. The carry cart according to claim 2, wherein the elastic main body connects the first attachment portion and the second attachment portion.

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