Shopping cart

Abstract

Without using training wheels, have the front wheels go over the obstacle. [Solution] A handle shaft 30 having a central axis CL1 is connected to the cargo bed 20 by a connecting portion 29. The front wheels 32 are supported by the handle shaft 30 via a link member 37 and an arm 41, which are respectively provided below the connecting portion 29. The link member 37 is attached to the handle shaft 30 and has a link body portion 39 located behind the front axle 33. The arm 41 has an arm body portion 42 that supports the front axle 33. The arm body portion 42 is supported by the link shaft 40 so as to be rotatable in the vertical direction relative to the link body portion 39, located behind the front wheels 32. The elastic portion 55 is located behind the arm 41 and is elastically deformed 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 located behind the central axis CL1 and below the connecting portion 29.

Description

Technical Field

[0004] , , , , , , ,

[0005] , , ,

[0001] The present invention relates to a carrier cart that includes wheels that roll on a road surface by rotating around an axle, and that 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 down on the top surface, forward tipping of the walking assist device is suppressed.

[0003] When the main wheel has overcome 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 overcoming the step.

Prior Art Documents

Patent Documents

[0006] A carry cart to solve the above problems comprises: wheels that roll on the road surface; a loading platform positioned above the point where the wheels make contact with the road surface; and a handle shaft having a central axis extending in a direction intersecting the horizontal plane and connected to the loading platform by a connecting part; wherein the wheels are supported by the handle shaft via link members and arms provided below the connecting part and consist of front wheels that roll by rotation around the front axle and rear wheels that roll behind the front wheels in the direction of travel, and the carry cart travels forward in the direction of travel by the rolling of each wheel, wherein the link members are the handle shaft A carry cart that is attached to the front axle and has a link body portion located behind the front axle in the direction of travel, the arm supports the front axle and has an arm body portion located behind the front axle in the direction of travel and supported by a link shaft so as to be rotatable in the vertical direction relative to the link body portion, and further, an elastic portion is arranged 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 wheel and the rear wheel in contact with the same horizontal surface as the road surface, the link shaft is located behind the central axis and below the connecting portion. [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 of the carry cart in the above embodiment, showing the front wheels being lifted. [Figure 9] Figure 9 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 10] Figure 10 is an explanatory diagram illustrating the amount of sinking of the link member (the amount of downward movement of the link shaft) when the front wheel contacts the corner of a step. [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, a loading platform 20 on which the goods 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 carry cart CC moves forward in the direction of travel due to the rolling motion of each wheel. In Figures 1, 2, 4, 7-9, the direction of travel is from right to left in each figure, and the forward direction in the direction of travel is to the left in each figure.

[0010] In the following description, the forward direction of the carry cart CC will be referred to as "forward," and the reverse direction as "rear." The vertical direction refers to the up and down direction of the carry cart CC, and the left and right direction is the direction perpendicular to both the forward and vertical directions. The left and right direction is the width direction of the carry cart CC and coincides with the left and right direction when the carry cart CC is moving forward.

[0011] <Road surface 10> The road surface 10 on which the carry cart CC travels has a convex step 12. Here, in order to distinguish the convex step 12 from other parts of the road surface 10, the latter will be referred to as the general road surface 11. The upper surface of the step 12 will be referred to as the top surface 13, and the rear upper corner of the step 12 will be referred to as the rear corner 14. For the sake of simplicity, here we will assume that both the general road surface 11 and the top surface 13 are composed of horizontal surfaces.

[0012] The top surface 13 is, for example, the top surface of a sidewalk. The general road surface 11 is, for example, the top surface of a roadway. Next, we will explain the individual components that make up the Carry Cart CC.

[0013] <Cargo bed 20> As shown in Figures 2 to 4, the cargo bed 20 comprises a cargo bed body 21 and mounting protrusions 23. The cargo bed body 21 is a box-shaped structure with a bottom, and a storage compartment 22 having an opening 22a at its upper end. The transported object C1 can be loaded into and unloaded from the storage compartment 22 through the opening 22a. The mounting protrusions 23 are provided on the upper part of the cargo bed body 21, at least adjacent to the front of the opening 22a. In this embodiment, in addition to the above location, the mounting protrusions 23 are also provided on the upper part of the cargo bed body 21, and adjacent to both the left and right sides of the opening 22a.

[0014] Rear wheel support sections 24 are fixed to both sides of the cargo bed body 21 in the left-right direction. The two rear wheel support sections 24 are spaced apart from each other in the left-right direction. As shown in Figures 2 and 4, the lower part of each rear wheel support section 24 extends below the bottom surface 21a of the cargo bed body 21.

[0015] As shown in FIGS. 1, 3, and 5, among the mounting protrusions 23, a bearing portion 25 is fixed to a portion in front of the opening 22a and at the central portion in the left - right direction of the loading platform 20. 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, the pair of bearing plate portions 26 are each inclined with respect to the horizontal plane such that the front side is positioned higher. The connecting plate portion 27 is inclined with respect to the vertical plane such 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 mounting protrusion 23 by fastening members 28 such as bolts and nuts.

[0016] <Handle shaft 30> [[ID=⑥]]As shown in FIG. 2, the handle shaft 30 has a central axis CL1 extending in a direction intersecting the horizontal plane. In the present embodiment, the central axis CL1 is inclined with respect to the vertical line VL such that the upper side is positioned more rearward. Here, the angle formed by the central axis 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 FIGS. 1 and 5, the lower portion of the handle shaft 30 is inserted through the pair of bearing plate portions 26 described above. The lower end portion 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 a steering shaft and is rotatable about the central axis CL1.

[0018] The handle shaft 30 is connected to the front upper end portion of the loading platform 20 by the fastening member 28 via the bearing portion 2{5}. Incidentally, the location where the handle shaft 30 is connected to the loading platform 20 by the fastening member 28, more specifically, the location where the fastening member 28 is inserted through the connecting plate portion 27, may be referred to as the connecting portion 29 of the handle shaft 30 with respect to the loading platform 20.

[0019] Furthermore, as shown in Figure 2, the carry cart CC is equipped with a gripping portion 31 attached to the upper end of the handle shaft 30 and which is held by the user of the carry cart CC. The user can rotate the handle shaft 30 around the central axis CL1 by changing the orientation of the gripping portion 31.

[0020] <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.

[0021] The front wheel 32 is supported on the handle shaft 30 by a support mechanism M1 located below the connecting portion 29. 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] <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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] <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. 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.

[0033] <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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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, in this embodiment, 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 located behind the central axis CL1 of the handle shaft 30 and below the connecting portion 29.

[0038] Furthermore, the front wheel 32 is supported on the handle shaft 30 by the support mechanism M1. Therefore, 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 8, 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 8, 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 9, when the front wheel 32 rides onto the step 12, that is, when it passes the corner 14, the reaction force RF1 (see Figures 1 and 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 9, 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 9, and when they overcome the step 12, both the front wheels 32 and both rear wheels 34 come into contact with the top surface 13 of the step 12, although this is not shown in the figure.

[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] Incidentally, as shown in Figures 1 and 7, when the front wheels 32 come into contact with the rear corner 14 of the step 12 from behind as the carry cart CC moves (self-propelled), the handle shaft 30 attempts to rotate in the direction indicated by arrow D, with the connecting part 29 as the pivot point. The link member 37 sinks down, and the link shaft 40 moves downward. In contrast, the vertical position of the front axle 33 does not change. Therefore, the arm 41 rotates upward around the link shaft 40, compressing and elastically deforming the elastic part 55. The amount of this elastic deformation increases as the amount S of sinking of the link member 37 increases. And, by the amount of the above elastic deformation, the amount of elastic deformation of the elastic part 55 that can be used to lift the front wheels 32 when going over the step decreases.

[0053] On the other hand, as shown in Figure 10, when the handle shaft 30 rotates by a certain angle θ3 with the connecting portion 29 as the pivot point, the amount of sinking S of the link member 37 and the amount of downward movement of the link shaft 40 differ depending on the position of the link shaft 40 before rotation. For example, when the link shaft 40 is located behind the central axis CL1 of the handle shaft 30, which is inclined so that the upper part is located further back as described above, the amount of sinking S of the link member 37 is less than the amount of sinking S when it is located forward. The same applies to the amount of downward movement of the link shaft 40. Moreover, when the link shaft 40 is located behind the central axis CL1, the amount of sinking S and the amount of movement decrease as it approaches the point directly below the connecting portion 29.

[0054] In this embodiment, as shown in Figures 1 and 7, the link shaft 40 is located behind the central axis CL1 of the handle shaft 30 and below the connecting portion 29. Therefore, the amount of sinking S of the link member 37 when the front wheel 32 contacts the corner 14 of the step 12 is small (see Figure 10). Also, the amount of downward movement of the link shaft 40 is small.

[0055] Here, as shown in Figure 7, the distance between the link shaft 40 and the connecting portion 29 is defined as the link shaft connecting portion distance L1. The angle that the imaginary line IL passing through the link shaft 40 and the connecting portion 29 makes with respect to the vertical line VL is defined as the link shaft connecting portion angle θ2. The position of the link shaft 40, in this case the vertical position of the link shaft 40 with respect to the general road surface 11, is defined as the link shaft position P. Figure 10 shows the amount of sinking S of the link member 37 when the handle shaft 30 rotates at a certain angle θ3, for example, 3 degrees, with the connecting portion 29 as the pivot point. The unit of angle is degrees [deg].

[0056] As shown in Figures 7 and 10, four combinations were set for multiple types of caster angles θ1, multiple types of link shaft connection distances L1, multiple types of link shaft connection angles θ2, and multiple types of link shaft positions P. Three embodiments (Embodiments 1 to 3) and a comparative example were set as combinations. The amount of sinking S of the link member 37 for each combination was calculated. The results are shown in Table 1.

[0057] [Table 1]

[0058] In Examples 1 to 3, the link shaft 40 is located behind the central axis CL1 and below the connecting portion 29. In Examples 1 to 3, the distance L1 between the link shaft connection parts is set to a common value (153.66 mm). In Examples 1 to 3, the caster angle θ1, the link shaft connection part angle θ2, and the link shaft position P are set to different values.

[0059] Note that "Initial" in Table 1 indicates the value before the front wheel 32 makes contact with the corner 14. "After Rotation" in the same Table 1 indicates the value after the handle shaft 30 rotates by an angle θ3 (3 degrees in this case) in the direction indicated by arrow D, with the connecting part 29 as the pivot point, due to the front wheel 32 making contact with the corner 14.

[0060] In the comparative example, the link shaft 40 is set forward of the central axis CL1, and the caster angle θ1 is set to 0 degrees. From Table 1 above, it can be seen that the amount of sinking S of the link member 37 is -3.582 mm in the comparative example, while it is less in Examples 1 to 3, ranging from -0.337 mm to -1.727 mm.

[0061] As described above, if the amount of sinking S of the link member 37 is small and the amount of downward movement of the link shaft 40 is small, the amount of upward rotation of the arm 41 around the link shaft 40 is small. The amount of compressive elastic deformation of the elastic part 55 is reduced, and as a result, the amount of elastic deformation that the elastic part 55 can use to lift the front wheel 32 when going over a step is increased.

[0062] <Effects of this embodiment> (1) As shown in Figure 1, a link member 37 is attached to the handle shaft 30. 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.

[0063] 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.

[0064] Furthermore, as shown by arrow A in Figure 8, 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.

[0065] 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.

[0066] (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 to get the front wheels over the step.

[0067] 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.

[0068] 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.

[0069] (3) 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 behind the central axis CL1 of the steering shaft 30 and below the connecting portion 29.

[0070] Therefore, by reducing the amount S of sinking of the link member 37 when the front wheel 32 contacts the corner 14 of the step 12, the amount of elastic deformation of the elastic part 55 when contacting the step can be reduced. The elastic deformation of the elastic part 55 can be effectively utilized for the front wheel 32 to overcome the step.

[0071] (4) As shown in Figures 1 and 2, the central axis CL1 of the handle shaft 30 is inclined with respect to the vertical line VL such that the upper side 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.

[0072] (5) As shown in Figures 1 and 6, 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.

[0073] Therefore, even if the arm 41 rotates around the link shaft 40 and the direction of the load applied to the elastic part 55 changes, that load is more 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 more likely to undergo compressive elastic deformation. This suppresses large changes in the biasing force of the elastic main body 56 due to changes in the direction of the applied load.

[0074] <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.

[0075] (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.

[0076] (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.

[0077] 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.

[0078] The front wheel 32 and the rear wheel 34 may have different wheel diameters. (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.

[0079] - 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.

[0080] (Matters concerning the elastic part 55) • 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.

[0081] (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.

[0082] 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.

[0083] 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.

[0084] 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]

[0085] 10…road surface 20...Cargo bed 29...Connection part 30... Handle shaft 32…Front wheel 33…Front axle 34...Rear wheel (wheel) 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 57...First attachment part 58…Second attachment part CC...Carry Cart CL1…Center axis line VL…Plumb line

Claims

1. It comprises wheels that roll on the road surface, a loading platform positioned above the point where the wheels make contact with the road surface, and a handle shaft having a central axis extending in a direction intersecting the horizontal plane and connected to the loading platform by a connecting part, The cart comprises a front wheel that is supported on the handle shaft via link members and arms provided below the connecting portion and rolls by rotation around the front axle, and a rear wheel that rolls behind the front wheel in the direction of travel, and the cart moves forward in the direction of travel by the rolling of each wheel, The link member is attached to the handle shaft and has a link body portion located behind the front axle in the direction of travel. The arm supports the front axle and has an arm body that is supported by a link shaft so as to be rotatable in the vertical direction 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 located behind the central axis and below the connecting portion.

2. The carry cart according to claim 1, wherein the central axis of the handle shaft is inclined with respect to the vertical line such that the upper side is located further back 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 carry cart according to claim 1 or 2, wherein the elastic part comprises a first attachment part attached to the arm mounting part, a second attachment part attached to the bracket body part, and an elastic body part formed of rubber so as to be elastically deformable and connecting the first attachment part and the second attachment part.

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