Luggage cart

Abstract

This luggage cart (CC) comprises: front wheels 32 and rear wheels; and a cart body (19). The front wheels (32) are each supported by the cart body (19) via a link member (37) and an arm (41), and roll by rotating about a front axle (33). An arm body (42) of the arm (41) supports the front axle (33), and is rotatably supported by a link shaft (40) with respect to a link body (39) at the rear of the front axle (33). An elastic part (55) that is elastically deformed as the arm (41) rotates upward about the link shaft (40) is disposed behind the arm (41). In a state in which both the front wheels (32) and the rear wheels are in contact with the same horizontal surface which is a road surface (10), the link shaft (40) is disposed at a position same as or higher than the front axle (33) in the vertical direction.

Description

Carry cart

[0001] The present disclosure relates to a carry cart that has wheels that rotate about axles to roll on a road surface, and that travels by the rolling of the wheels.

[0002] In the field of carry carts, various structures have been proposed for enabling wheels to overcome convex steps. For example, a walking aid described in Patent Document 1 is provided with main wheels corresponding to the front wheels, and auxiliary wheels are provided in front of the main wheels in the direction of travel. The contact surfaces of the auxiliary wheels are set above the contact surfaces of the main wheels. A link mechanism is interposed between the auxiliary wheels and the main wheels. When the main wheels contact a step, they are moved rearward and upward in the direction of travel. This movement reduces the impact when the main wheels contact the step. Furthermore, the movement of the main wheels is transmitted to the auxiliary wheels via the link mechanism, causing the auxiliary wheels to pivot downward. The auxiliary wheels contact the top surface of the step and press down on the top surface, preventing the walking aid from tipping forward.

[0003] When the main wheels overcome the step, the auxiliary wheels are rotated upward by the elastic bodies and return to their original positions, and the walking aid returns to the same position as before the step was overcome.

[0004] Japanese Patent Application Laid-Open No. 2006-306246

[0005] The technology described in Patent Document 1 requires auxiliary wheels to allow the main wheels (front wheels) to overcome steps. However, there is a demand for a carry cart that allows the front wheels to overcome steps without using such auxiliary wheels.

[0006] One aspect of the present disclosure provides a carry cart. The carry cart includes wheels that roll on a road surface and a cart body that is positioned above the contact points of the wheels with the road surface and on which a transported object is placed. The wheels include front wheels that are supported on the cart body via link members and arms and that roll by rotating around front axles, and rear wheels that are supported on the cart body rearward of the front wheels in the direction of travel and that roll by rotating around rear axles. The carry cart travels forward in the direction of travel by the rolling of each wheel. The link member is attached to the cart body and has a link body behind the front axles in the direction of travel. The arm supports the front axles and has an arm body behind the front axles in the direction of travel that is rotatably supported by a link shaft relative to the link body. An elastic portion that elastically deforms as the arm rotates upward around the link shaft is located behind the arm in the direction of travel. With both the front wheels and the 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 at a higher position than the front axle.

[0007] FIG. 1 is a diagram showing one embodiment of a carry cart, and is a partial side cross-sectional view of a support mechanism for a front wheel. FIG. 2 is a side view of the carry cart in the embodiment, in which the front wheel contacts the rear corner of a step. FIG. 3 is a perspective view of the carry cart in the embodiment. FIG. 4 is a bottom view of the carry cart in the embodiment. FIG. 5 is a partial perspective view showing an enlarged view of the support mechanism in FIG. 3. FIG. 6 is an exploded perspective view showing the components of the support mechanism in FIG. 3. FIG. 7 is a partial side view showing an enlarged view of the support mechanism in FIG. 2. FIG. 8 is a partial side view showing the attachment state of the elastic part in the support mechanism in FIG. 7. FIG. 9 is a partial side view of the carry cart in the embodiment, in which the front wheel is being lifted. FIG. 10 is a partial side view of the carry cart in the embodiment, in which the front wheel rolls on the top surface of a step. FIG. 11 is an explanatory diagram illustrating an example of the positional relationship between the front axle, link shaft, connecting part, etc. FIG. 12 is an explanatory diagram illustrating another example of the positional relationship between the front axle, link shaft, connecting part, etc. Fig. 13 is a schematic diagram showing an example of the positional relationship between the front axle, link shaft, connecting portion, etc. Fig. 14 is a schematic diagram showing another example of the positional relationship between the front axle, link shaft, connecting portion, etc. Fig. 15 is a characteristic diagram showing the relationship between load and elastic deformation amount for the elastic portion.

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

[0009] The rolling of each wheel causes the carry cart CC to travel forward in the direction of travel. In Figures 1, 2, 4, and 7 to 10, the direction of travel is from right to left in each figure, and the front in the direction of travel is the left side in each figure.

[0010] In the following description, the forward direction of the carry cart CC is referred to as the front, and the backward direction is referred to as the rear. Furthermore, the up-down direction refers to the vertical direction of the carry cart CC, and the left-right direction refers to the direction perpendicular to both the forward direction and the up-down direction. The left-right direction refers to the width direction of the carry cart CC, and corresponds to the left-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 portions of the road surface 10 that are not the step 12, the latter will be referred to as a general road surface 11. Furthermore, the upper surface of the step 12 will be referred to as a top surface 13, and the upper rear corner of the step 12 will be referred to as a rear corner 14. For ease of explanation, it is assumed here that both the general road surface 11 and the top surface 13 are horizontal surfaces.

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

[0013] <Loading Platform 20> As shown in Figures 2 to 4, the loading platform 20 includes a loading platform main body 21 and mounting protrusions 23. The loading platform main body 21 is box-shaped with a bottom and a storage section 22 having an opening 22a at its upper end. The load C1 can be loaded into and removed from the storage section 22 through the opening 22a. The mounting protrusions 23 are provided on the upper part of the loading platform main body 21, at least in a position adjacent to and in front of the opening 22a. In this embodiment, the mounting protrusions 23 are provided in addition to the above positions on the upper part of the loading platform main body 21, and also in positions adjacent to both the left and right sides of the opening 22a.

[0014] A rear wheel support portion 24 is fixed to each of the left and right sides of the bed body portion 21. The rear wheel support portions 24 are spaced apart from each other in the left and right direction. As shown in Figures 2 and 4, the lower portion of each rear wheel support portion 24 extends downward below the bottom surface 21a of the bed body portion 21.

[0015] As shown in Figures 1, 3, and 5, a bearing 25 is fixed to the mounting protrusion 23 at a portion forward of the opening 22a and at the center of the loading platform 20 in the left-right direction. The bearing 25 includes a pair of bearing plates 26 and a connecting plate 27. When the front wheels 32 and the rear wheels 34 are both in contact with the same horizontal surface, i.e., the road surface 10, the pair of bearing plates 26 are inclined with respect to the horizontal plane so that the front ends are positioned higher. The connecting plate 27 is inclined with respect to the vertical plane so that the upper ends are positioned further rearward. The connecting plate 27 connects the rear edges of the pair of bearing plates 26 together. The connecting plate 27 is fastened to the mounting protrusion 23 by fastening members 28, such as bolts and nuts.

[0016] <Steering Wheel Shaft 30> As shown in Figure 2, the steering wheel shaft 30 has a central axis CL1 that extends in a direction intersecting a horizontal plane. In this embodiment, the central axis CL1 is inclined with respect to the vertical line VL so that the upper part of the central axis CL1 is positioned more rearward. Here, the angle that the central axis CL1 makes with respect to the vertical line VL is referred to as the caster angle θ1. In this embodiment, the caster angle θ1 is set to 20° as an example, but is not limited to this.

[0017] 1 and 5, the lower portion of the handle shaft 30 is inserted into the pair of bearing plates 26. The lower end of the handle shaft 30 protrudes downward from the lower bearing plate 26. The handle shaft 30 is supported by the bearings 25 at both bearing plates 26. The handle shaft 30 constitutes a steering shaft and is capable of rotating about a central axis line CL1.

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

[0019] <Plural Wheels> As shown in FIGS. 2 and 4, the plural wheels include a single front wheel 32 and a pair of rear wheels 34.

[0020] The front wheels 32 are supported on the handle shaft 30 by a support mechanism M1 provided below the fastening members 28. The front wheels 32 are driven by a motor (not shown) as a power source, rotating about the front axle 33, and serve as drive wheels that provide propulsive force for traveling to the carry cart CC. The motor receives power from a battery (not shown) mounted on the loading platform 20 or the like. The motor may be, for example, an electric motor disposed inside or near the front wheels 32 to transmit power to the front wheels 32 and directly drive and rotate the front wheels 32, a so-called in-wheel motor. In the front wheels 32 of this embodiment, the in-wheel motor is used as the motor.

[0021] 5 and 6, the front wheels 32 and the front axles 33 are configured as an integral part. Both ends of the front axles 33 protrude from the front wheels 32 on either side in the direction in which the front axles 33 extend.

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

[0023] 2 and 4, the loading platform 20 is disposed above the contact points of the front wheels 32 and rear wheels 34 with the road surface 10, for example, the general road surface 11. The bottom surface 21a of the loading platform 20 is located higher than the lowermost ends of the front wheels 32 and rear wheels 34 and lower than the uppermost ends of the wheels.

[0024] The support mechanism M1 includes a link member 37, an arm 41, a bracket 51, and an elastic portion 55. <Link member 37> As described above, the lower end of the handle shaft 30 protrudes downwardly beyond 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 a fastening member 38 such as a bolt so as to be integrally rotatable.

[0025] 5 and 6, the link member 37 has a pair of link main bodies 39 that extend in the up-down direction and are located rearward of the front axle 33. The pair of link main bodies 39 are spaced apart from each other in the direction in which the front axle 33 extends. The distance between the link main bodies 39 is slightly larger than the dimension of the front wheel 32 in the direction in which the front axle 33 extends.

[0026] <Arm 41> The arm 41 includes a pair of arm main bodies 42 and an arm attachment portion 46. Each arm main body 42 includes 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 main bodies 42 are disposed on both sides of the front wheel 32 in the direction in which the front axle 33 extends.

[0027] 2, 6, and 7, when the front wheels 32 and both rear wheels 34 are in contact with a horizontal surface, such as the general road surface 11, the front plate 43 of each arm main body 42 is inclined relative to the general road surface 11 so as to be lower toward the front. The rear plate 45 of each arm main body 42 extends in the front-to-rear direction. The front plate 43 and the rear plate 45 of each arm main body 42 are bent so as to protrude diagonally forward and upward.

[0028] The arms 41 support the front axles 33, thereby supporting the front wheels 32 on the link members 37. More specifically, each front plate 43 has a notch 44 formed therein that extends obliquely upward and rearward from the front lower end of the front plate 43 when both the front wheels 32 and the rear wheels 34 are in contact with the same horizontal surface, i.e., the road surface 10. That is, the notch 44 of each front plate 43 is inclined with respect to the horizontal and vertical planes so that the more rearward the notch 44 is positioned, the higher it is. The portion of the front axle 33 that protrudes from the front wheels 32 is inserted into and supported by the notch 44 of each front plate 43. The arm attachment portion 46 connects the rear edges of the pair of arm main bodies 42 rearward of the front wheels 32.

[0029] The arm 41 configured as described above is disposed between a pair of link main bodies 39. More specifically, each arm main body 42 is disposed adjacent to the inside of the link main body 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 rotatable in the vertical direction relative to the adjacent link body 39 located rearward of the front wheel 32 and on the outer side in the direction in which the front axle 33 extends.

[0031] <Bracket 51> As shown in Figures 1, 2, and 6, the bracket 51 includes a flat bracket main body 52 and a pair of mounting plates 53. The pair of mounting plates 53 are adjacent to the outer sides of the link main body 39 in the direction in which the front axle 33 extends (see Figure 5). The bracket main body 52 is located rearward of the pair of link main bodies 39 and rearward of the arm mounting portion 46. The bracket main body 52 connects the rear edges of the pair of mounting plates 53. The bracket main body 52 is inclined with respect to the vertical line VL so that the upper portion of the bracket main body 52 is positioned more rearward when both the front wheel 32 and the rear wheel 34 are in contact with the same horizontal plane as the road surface 10. Each mounting plate 53 is fastened to the link main body 39 adjacent to the mounting plate 53 on the inner side in the direction in which the front axle 33 extends by a fastening member 54 such as a bolt. Each mounting plate portion 53 is connected to the adjacent link body portion 39 by the link shaft 40 .

[0032] 1 and 6 , the elastic portion 55 includes an elastic main body portion 56, a first attachment portion 57, and a second attachment portion 58. The elastic portion 55 is disposed between the arm attachment portion 46 and the bracket main body portion 52.

[0033] The elastic main body 56 is made of rubber and is elastically deformable, and has a central axis CL2. The elastic main body 56 is bowl-shaped with an open rear surface. The outer surface of the elastic main body 56 has a hemispherical curved surface 56a that curves to bulge forward. The inner surface of the elastic main body 56 has a hemispherical curved surface 56b that curves to concave forward. The elastic main body 56 has the characteristic that the amount of elastic deformation increases as the load input thereto increases.

[0034] The first and second covering portions 57 and 58 are formed from a material, such as metal, that is less susceptible to elastic deformation than the elastic main body portion 56, and have greater strength than the elastic main body portion 56. The first and second covering portions 57 and 58 are attached to the front and rear ends of the elastic main body portion 56. In other words, the first and second covering portions 57 and 58 are connected by the elastic main body portion 56.

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

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

[0037] As shown in FIG. 8 , the elastic portion 55 is disposed with the central axis CL2 tilted relative to the horizontal plane so that it is lower toward the rear. In other words, the second attachment portion 58 of the elastic portion 55 is tilted relative to the vertical line VL so that it is positioned further rearward toward the upper end. Here, the angle that the second attachment portion 58 forms with respect to the vertical line VL is referred to as the elastic portion mounting angle θ3. The unit of the elastic portion mounting angle θ3 is degrees (deg). The elastic portion mounting angle θ3 is set to a magnitude that aligns the direction of the force acting from the arm 41 to the elastic portion 55 when the arm 41 rotates upward about the link shaft 40 with the central axis CL2. The elastic portion mounting angle θ3 is preferably set to, for example, 5 to 15 degrees. In this embodiment, the elastic portion mounting angle θ3 is set to 10 degrees.

[0038] As described above, the front wheels 32 are supported on the cart body 19 at the handle shaft 30 by the support mechanism M1. Therefore, as shown in Figures 2 and 8, when the handle shaft 30 is rotated about the central axis CL1 in response to the operation of the grip 31, the direction in which the front axle 33 extends is changed in response to the rotation. By turning the front wheels 32, the traveling direction of the carry cart CC is changed.

[0039] <Operation of this embodiment> In describing the operation of this embodiment, it is assumed that the load C1 is placed on the platform 20 of the carry cart CC as shown in FIG.

[0040] When the front wheel 32 and both rear wheels 34 contact the general road surface 11, which is a horizontal plane, the bottom surface 21a of the loading platform 20 is in a horizontal state. As shown by arrow A in Figure 2, when the front wheel 32 is driven to rotate forward and downward by the motor, a propulsive force is generated in the front wheel 32 for moving the carry cart CC forward. This propulsive force is transmitted to the both rear wheels 34 via the arm 41, link member 37, handle shaft 30, loading platform 20, etc. The both rear wheels 34 are pulled forward by the transmitted propulsive force and rotate forward and downward in conjunction with the front wheels 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 travels (self-propels) forward along the general road surface 11 without tilting the bottom surface 21a. As shown in FIGS. 1 and 7 , as the carry cart CC travels (self-propels), the front wheels 32 contact the rear corner 14 of the step 12 from behind. This contact causes a force from the front wheels 32 to act diagonally forward and downward on the step 12. In particular, since a transported object C1 is loaded on the loading platform 20, when the front wheels 32 contact the step 12 and restrict the forward travel of the carry cart CC, the transported object C1 tends to move forward due to inertia. Therefore, the diagonally forward and downward force is more likely to act on the corner 14 from the front wheels 32. Meanwhile, as a reaction force to the above force, a reaction force RF1 acts on the front wheels 32 from the corner 14 in a diagonally upward and rearward direction. This reaction force RF1 is a force that tries to push back the front wheel 32 that is trying to roll forward.

[0042] If the carry cart CC is not designed to make it easier for the front wheels 32 to climb over the step 12, it will be difficult for the front wheels 32 to climb over the step 12. Furthermore, the higher the step 12, the more difficult it becomes for the front wheels 32 to climb over the step 12.

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

[0044] Furthermore, as described above, when the front wheel 32 rotating forward and downward comes into contact with the corner 14 of the step 12, a force acting diagonally downward and rearward acts from the front wheel 32 on the corner 14. 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 force Fa and a forward component force Fb act on the front wheel 32.

[0045] Then, the component force Fa is added to the upward force F1 acting on the front wheels 32 as the arm 41 rotates, lifting the front wheels 32. Meanwhile, the rear wheels 34 are still in contact with the general road surface 11. Therefore, as shown in Figure 9, the bottom surface 21a of the loading platform 20 is inclined relative to the horizontal plane so that it is lower towards the rear.

[0046] Here, the dimension from the lowest point of the front wheel 32 that has been lifted as described above to the top surface 13 of the step 12 is defined as the overlap (lap) Δh. As the wheel is lifted as described above, the overlap Δh decreases. As the overlap Δh decreases, the force required for the front wheel 32 to climb over the step 12 decreases. Unlike conventional carry carts, the front wheel 32 can easily climb over the step 12 without using training wheels.

[0047] 10, when the front wheel 32 runs over the step 12, that is, when it passes the corner 14, the reaction force RF1 (see FIG. 7) no longer acts on the front wheel 32. Due to the elastic restoring force of the elastic portion 55, the arm 41 tries to rotate downward about the link shaft 40 as shown by arrow C in FIG. 10, and the front wheel 32 returns to the same state as before it ran over the step 12.

[0048] The front wheels 32 contact the top surface 13 of the step 12, and both rear wheels 34 still contact the general road surface 11. The front wheels 32 are positioned higher than the rear wheels 34. The bottom surface 21a of the loading platform 20 remains inclined relative to the horizontal plane so that it becomes lower towards the rear.

[0049] When the front wheel 32 rotates 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, with the bottom surface 21a of the platform 20 tilted relative to the horizontal plane as described above, travels forward. As the carry cart CC travels, both rear wheels 34 come into contact with the rear corners 14 of the step 12 from behind, as shown in the figure. At this time, unlike when the front wheels 32 come into contact with the step 12, a force acts on the rear wheels 34 in an obliquely forward and upward direction, as described above. This is because, as shown in FIG. 2 , when the front wheels 32 come into contact with the corners 14 of the step 12, the bottom surface 21a of the platform 20 is not tilted relative to the horizontal plane. In contrast, when both rear wheels 34 come into contact with the corners 14, the bottom surface 21a of the platform 20 is tilted relative to the horizontal plane so that it is lower toward the rear.

[0050] Therefore, both rear wheels 34 can go over the step 12 with less force than when the front wheel 32 goes over the step 12. Furthermore, the propulsive force generated by the rotational driving of the front wheel 32 acts to pull both rear wheels 34 forward. This force causes both rear wheels 34 to rotate forward and downward as shown by arrow B in Figure 10, and when they go over the step 12, both the front wheel 32 and both rear wheels 34 come into contact with the top surface 13 of the step 12, although this is not shown.

[0051] Furthermore, if the front wheel 32 comes into contact with a new convex step while the carry cart CC continues to run on the top surface 13, the front wheel 32 and both rear wheels 34 will climb over this new step in the same way as when climbing over the step 12 from the general road surface 11.

[0052] When the front wheel 32 and both rear wheels 34 are in contact with the same horizontal surface, such as the general road surface 11, as the road surface 10, if the link shaft 40 is located lower than the front axle 33 (see FIG. 12), the following phenomenon may occur. That is, the lower surfaces of the link member 37, arm 41, and bracket 51 in FIG. 5, which are below the portion through which the link shaft 40 is inserted, are located at the lowest point of the support mechanism M1. In other words, 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, components, etc., of the carry cart CC located between the front axle 33 and both rear axles 35, as shown in FIG. 2. Furthermore, when the front wheel 32 goes over a step and the elastic portion 55 is elastically deformed to lift the front wheel 32, there is a risk that the undersides of the link member 37, arm 41 and bracket 51 below the portion through which the link shaft 40 is inserted may interfere with the top surface 13.

[0053] In this regard, in this embodiment, as shown in Figures 7 and 11, when the front wheel 32 and the rear wheel 34 are in contact with the same horizontal surface, which is the road surface 10, the link shaft 40 is located at the same height as the front axle 33. The minimum ground clearance in this case 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 portion 55 is elastically deformed to lift the front wheel 32, and the link member 37, arm 41, and bracket 51 are less likely to interfere with the top surface 13 of the step 12.

[0054] As shown in Figure 12, the deviation between the position of the link shaft 40 and the position of the front axle 33 in the vertical direction is referred to 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. In contrast, if the link shaft 40 is lower than the front axle 33, the height difference ΔD1 will be a negative (-) value. In this embodiment, in which the link shaft 40 is located at the same height as the front axle 33, the height difference ΔD1 is 0 mm.

[0055] Furthermore, various characteristics of the carry cart CC vary depending on the dimensional and positional relationships of the front axle 33, arm 41, link member 37, etc. The various characteristics include the ability to climb over steps.

[0056] 11 and 12 , the dimensional relationships include the height difference ΔD1, the link axle-to-elastic-portion distance L1, the link axle-to-axle distance L2, the lever ratio R, and the link angle θ4. The link axle-to-elastic-portion distance L1 is the distance between the link axle 40 and the portion of the arm 41 that is connected to the elastic portion 55 by the fastening member 61 (hereinafter referred to as the connecting portion 47). The link axle-to-axle distance L2 is the distance between the link axle 40 and the front axle 33. The lever ratio R is the ratio (L2 / L1) of the link axle-to-axle distance L2 to the link axle-to-elastic-portion distance L1. The link angle θ4 is the angle between an imaginary line passing through the link axle 40 and the connecting portion 47 and an imaginary line passing through the link axle 40 and the front axle 33.

[0057] 11 and 12 differ in the following respects: The distance L2 between the link axles in FIG. 12 is longer than the distance L2 between the link axles in FIG.

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

[0059] The link angle θ4 in Fig. 12 is smaller than the link angle θ4 in Fig. 11. Figs. 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 link shaft-to-axle distance L2 is set to the same value as the link shaft-to-elastic portion distance L1. The lever ratio R is 1.0. An imaginary line passing through the front axle 33 and the connecting portion 47 forms an angle of 45 degrees (°) with an imaginary line passing through the front axle 33 and the link shaft 40.

[0061] 14, the link shaft-to-axle distance L2 is set to a value obtained by multiplying the link shaft-to-elastic portion distance L1 by √3. The lever ratio R is 1.7. The angle between an imaginary line passing through the front axle 33 and the connecting portion 47 and an imaginary line passing through the front axle 33 and the link shaft 40 is 30 degrees (°).

[0062] 13 and 14 are merely examples, and other values ​​may be used. As previously mentioned, when the front wheel 32 comes into contact with the corner 14 of the step 12 as shown in FIG. 1 , a force F1 (load) that tends to lift the front wheel 32 is applied to the front wheel 32. Furthermore, as shown in FIGS. 13 and 14 , when the arm 41 rotates upward about the link shaft 40, a force F2 that tends to elastically deform the elastic main body portion 56 acts on the elastic portion 55 through the connecting portion 47. In FIGS. 13 and 14 , the elastic main body portion 56 before elastic deformation is indicated by a solid line, and the elastic main body portion 56 after elastic deformation is indicated by a two-dot chain line.

[0063] When the arm 41 is rotated upward about the link shaft 40 by the force F1, the front wheel 32 and the front axle 33 are lifted, for example, by 1.3 mm, as shown by the two-dot chain line in Figure 13. This causes the elastic main body 56 to elastically deform 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 the front axle 33.

[0064] 14, when a force F1 of the same magnitude as in FIG. 13 is applied to the front wheel 32 and front axle 33, the arm 41 is rotated upward about the link shaft 40. As indicated by the two-dot chain line in FIG. 14, the front wheel 32 and front axle 33 are lifted by 3.8 mm, and the elastic main body 56 is elastically deformed by 2.2 mm. This is because a load that is √3 times the load applied to the front wheel 32 and front axle 33 is applied to the elastic part 55. Because the amount of elastic deformation of the elastic main body 56 is greater, the front wheel 32 is lifted even more.

[0065] 12 , if the link shaft 40 is located lower than the front axle 33 and the link shaft-to-axle distance L2 is long, the load input to the elastic portion 55 when going over a step increases, and the amount of lift of the front wheel 32 increases. This increases the possibility that the link member 37, arm 41, and bracket 51 will interfere with the top surface 13 of the step 12.

[0066] On the other hand, when the link shaft 40 is positioned at the same height as the front axle 33 or at a higher position, if the link shaft-to-axle distance L2 is long, interference between the link member 37, the arm 41, and the top surface 13 of the bracket 51 is less likely to occur, making it easier for the front wheel 32 to climb over the step 12.

[0067] Furthermore, the longitudinal dimension of the support mechanism M1, i.e., the longitudinal dimension of the entire link member 37, arm 41, bracket 51, and elastic portion 55, is affected by the link shaft-to-axle distance L2. The shorter the link shaft-to-axle distance L2, the smaller the longitudinal dimension, and therefore 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 or higher than the front axle 33. Based on this assumption, it is preferable to determine the distance L1 between the elastic portions of the link shafts, the distance L2 between the link shafts and the axles, the link angle θ4, etc., while taking into consideration the ease with which the front wheel 32 can get over the step 12, the dimensions in the fore-and-aft direction, etc.

[0069] Furthermore, as shown in Table 1, nine combinations were set for multiple types of height differences ΔD1, multiple types of link axle-to-elastic portion distances L1, multiple types of link axle-to-axle distances L2, and multiple types of link angles θ4. The combinations included eight examples (Examples 1 to 8) and one comparative example. In Examples 1 to 8, three types of height differences ΔD1 were set in the range of -10 mm to 10 mm, while in the comparative example, the height difference ΔD1 was set to -4.5 mm. Furthermore, in Examples 1 to 8, seven types of lever ratios 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, an evaluation was made as to whether the front wheel 32 could climb over the step 12. In this case, an elastic part 55 having the characteristics shown in Fig. 15 was used in terms of the relationship between the input load and the amount of elastic deformation. The elastic part 55 used had a spring constant of 60 N / mm, i.e., an elastic part 55 requiring a load of 60 Newtons (N) to elastically deform by 1 mm.

[0071] It was confirmed that the front wheel 32 was able to climb over the step 12 in all of the examples and comparative examples. It was confirmed that the front wheel 32 was able to climb over the step 12 when the lever ratio R was set to any value between 2.0 and 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, it is not intended to deny the lever ratio R being set to less than 2.0 or to a value greater than 5.5.

[0072] Furthermore, in Examples 2, 4, 6 and the comparative example, where the height difference ΔD1 is negative (-), there is a high possibility that the undersides of the link member 37, arm 41 and bracket 51 at the points where the link shaft 40 is inserted will interfere with the top surface 13 of the step 12.

[0073] In this embodiment, as shown in FIGS. 1, 6, and 8, the outer surface of the elastic main body portion 56 of the elastic portion 55 has a hemispherical curved surface 56a. As the arm 41 rotates, a rearward and downward load (see force F2 in FIGS. 13 and 14) is applied to the elastic portion 55. In contrast, when the front wheels 32 and both rear wheels 34 are in contact with the same horizontal surface, i.e., the road surface 10, the central axis CL2 of the elastic main body portion 56 is inclined relative to the horizontal plane so as to be lower toward the rear. The second attachment portion 58 of the elastic portion 55 is inclined relative to the vertical line VL so as to be positioned further rearward toward the upper side. Therefore, a load is more likely to be applied from the arm 41 to the elastic main body portion 56 in the direction along the central axis CL2 than when the central axis CL2 is not inclined relative to the horizontal plane or when the second attachment portion 58 is not inclined relative to the vertical line VL.

[0074] 1, a link member 37 is attached to the handle shaft 30 of the cart body 19. An arm 41 supporting the front axle 33 is supported by the link shaft 40 so as to be rotatable in the vertical direction relative to the link member 37. An elastic portion 55 is disposed behind the arm 41 and is compressively elastically deformed as the arm 41 rotates upward around the link shaft 40.

[0075] Therefore, when the front wheel 32 comes into contact with the corner 14 of the step 12, a reaction force RF1 acting diagonally upward and rearward is applied to the front wheel 32 from the corner 14, causing compressive elastic deformation of the elastic main body 56 of the elastic part 55, thereby rotating the arm 41 upward. An upward force F1 can be applied to the front wheel 32.

[0076] 9, when the front wheel 32 rotating downward and forward comes into contact with the corner 14, a reaction force RF2 directed obliquely upward and forward acts on the front wheel 32 from the corner 14. An upward component force Fa of this reaction force RF2 can be applied to the front wheel 32.

[0077] The force F1 and the component force Fa lift the front wheel 32, reducing the engagement allowance Δh and reducing the force required to make the front wheel 32 climb over the step 12. As a result, the front wheel 32 can climb over the step 12 without using training wheels.

[0078] (2) In the case of a type of carry cart that is pushed forward by the user (non-self-propelled), if the front wheels come into contact with the protruding step 12 and are prevented from moving, the user lifts the front wheels of the carry cart. This operation allows the front wheels to climb over the step 12.

[0079] In contrast, with a self-propelled carry cart, the user does not have to lift the front wheel as described above. In this regard, in this embodiment, the front wheel 32 is a drive wheel that is driven by a motor to provide propulsion for travel. The carry cart CC, in which the front wheel 32 is a drive wheel, employs the above-described configuration (1). That is, the carry cart CC includes the link member 37, the arm 41, and the elastic portion 55.

[0080] Therefore, although the carry cart CC is self-propelled without being operated by the user, the front wheels 32 can be made to climb over the step 12. Therefore, the above configuration (1) is particularly useful for the carry cart CC of this embodiment, which does not have any means for climbing over the step 12 other than by using the driving force of the front wheels 32 to climb over the step 12.

[0081] (3) As shown in Figure 2, when the front wheel 32 and both rear wheels 34 are 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, as shown in Figures 1 and 7.

[0082] Therefore, unlike when the link shaft 40 is lower than the front axle 33 (see Figure 12), when the front wheel 32 climbs over a step, the undersides 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.

[0083] 1 and 6, the elastic portion 55 includes an elastic main body 56 that is made of rubber and is elastically deformable, and has a central axis CL2. The outer surface of the elastic main body 56 has a hemispherical curved surface 56a that curves forward.

[0084] Therefore, even if the arm 41 rotates around the link shaft 40 and the direction of the load (see force F2 in FIGS. 13 and 14 ) input to the elastic portion 55 changes, the load is likely to act on the elastic main body portion 56. Regardless of the change in the direction of the input load, the elastic main body portion 56 is likely to be compressed and elastically deformed. This makes it possible to prevent the biasing force of the elastic main body portion 56 from changing significantly due to a change in the direction of the input load.

[0085] 1, 6, and 8, the elastic portion 55 is disposed such that the central axis CL2 of the elastic main body 56 is inclined relative to the horizontal plane so as to be lower toward the rear. The second covering portion 58 is disposed such that the central axis CL2 is inclined relative to the vertical line VL so as to be positioned further rearward toward the upper side.

[0086] Therefore, a load can be applied to the elastic portion 55 in the direction along the central axis line CL2 from the arm 41 that rotates upward about the link shaft 40. This allows the elastic portion 55 to be elastically deformed more efficiently.

[0087] (6) As shown in Figure 2, the handle shaft 30 is inclined relative to the vertical line VL so that the upper part is positioned further rearward. Therefore, when a load is applied to the grip part 31, the load can be prevented from being transmitted to the elastic part 55 via the handle shaft 30, the link member 37, etc.

[0088] <Modifications> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0089] 2, the vertical position of the loading platform 20 may be changed, provided that the front wheels 32 and both rear wheels 34 are positioned higher than the points where they contact the road surface 10, for example, the general road surface 11. For example, the bottom surface 21a of the loading platform 20 may be positioned higher than the uppermost ends of the front wheels 32 and the rear wheels 34.

[0090] (Matters related to the steering shaft 30) The central axis CL1 of the steering shaft 30 in Figure 2 may extend vertically. (Matters related to the wheels) The number of front wheels 32 may be changed to multiple. Also, the number of rear wheels 34 may be changed to three or more. Also, if the number of front wheels 32 is changed to multiple, the number of rear wheels 34 may be changed to one.

[0091] The front wheels 32 may be driven to rotate by a motor provided outside the front wheels 32. The front wheels 32 may be driven by a power source other than a motor. The rear wheels 34 may be drive wheels that are driven to rotate by a power source, and the front wheels 32 may be driven wheels. Furthermore, in addition to the front wheels 32, the rear wheels 34 may be drive wheels that are driven to rotate by a power source.

[0092] The wheel diameters (diameters) of the front wheels 32 and the rear wheels 34 may be different. (Matters related to the link axle 40) The link axle 40 may be positioned higher in the vertical direction than the front axle 33, with the front wheels 32 and both rear wheels 34 in contact with the same horizontal surface as the road surface 10. In this case, the same effects and advantages as those of the above embodiment in which the link axle 40 is positioned at the same vertical position as the front axle 33 can be obtained.

[0093] 5 and 6, the front plate 43 and the rear plate 45 of each arm body 42 do not necessarily have to be bent. Each arm body 42 may have a triangular plate shape, for example.

[0094] In cases such as when the front wheels 32 are not driven to rotate by a motor, the front axles 33 may be separated from the front wheels 32. In this case, instead of the cutouts 44, bearing holes may be formed in the front end portions of the arm main bodies 42. The portions of the front axles 33 that protrude from the front wheels 32 to both sides in the direction in which the front axles 33 extend may be inserted into the bearing holes of the respective arm main bodies 42, thereby being supported by the respective arm main bodies 42. In order to insert the portions of the front axles 33 that protrude from the front wheels 32 into the bearing holes of the respective arm main bodies 42, the pair of arm main bodies 42 in the arm 41 may be separated.

[0095] (Matters regarding the elastic portion 55) The elastic portion 55 may be one in which the outer surface of the elastic main body portion 56 has a hemispherical curved surface 56a and the inner surface of the elastic main body portion 56 does not have a hemispherical curved surface 56b.

[0096] The elastic portion 55 may be an elastic main body portion 56 whose outer surface 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.

[0097] An elastic body different from that used in the above embodiment may be used as the elastic portion 55. For example, a spring such as a coil spring or a leaf spring may be used as the elastic portion 55. Furthermore, an elastic body other than a spring may be used as the elastic portion 55.

[0098] (Other Matters) The carry cart of the present disclosure may be applied to a non-self-propelled carry cart. According to this modification, when the front wheels 32 come into contact with the step 12, the front wheels 32 can be caused to climb over the step 12 without the user having to perform an operation such as lifting the front wheels 32. This makes it easier for the user of the carry cart CC to climb over the step 12 even when the front wheels 32 come into contact with the step 12, making the carry cart CC easier to use.

[0099] The carry cart CC may include a seat for a user to sit on and a shopping basket. The carry cart CC may include a structure for detachably attaching a shopping basket. The carry cart CC may also include a hook for hanging a carrier bag, a purse, or other bag.

[0100] The carry cart CC may be provided with a brake mechanism for adjusting the traveling speed or stopping the travel of the carry cart CC. In this modification, by applying a braking force to at least one of the front wheels 32 and the rear wheels 34 while the carry cart CC is traveling, the rotational speed of the wheels and therefore the traveling speed of the carry cart CC can be adjusted. In addition, by stopping the rotation of at least one of the front wheels 32 and the rear wheels 34, the travel of the carry cart CC can be stopped.

[0101] The carry cart CC may also be provided with a brake mechanism for keeping the carry cart CC stationary when parked. In the case of a carry cart CC with a seat, the carry cart CC may also be provided with a brake mechanism for keeping the carry cart CC stationary when a person sits on the seat.

Claims

1. A carry cart comprising wheels that roll on a road surface, and a cart body portion on which a transported object is placed, the wheels being front wheels supported on the cart body portion via link members and arms and rolling around front axles, and rear wheels supported on the cart body portion behind the front wheels in the direction of travel and rolling around rear axles, the carry cart running forward in the direction of travel by the rolling of the wheels, wherein the link members are attached to the cart body portion and have a link body portion behind the front axles in the direction of travel, the arm supports the front axles and has an arm body portion behind the front axles in the direction of travel that is supported by a link shaft to be rotatable relative to the link body portion, and 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, A carry cart in which, with both the front wheels and the 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 at a higher position than the front axle.

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

3. A carry cart as described in claim 2, further comprising a bracket attached to the link main body portion, wherein the bracket has a bracket main body portion rearward of the arm in the direction of travel, and the arm further comprises an arm attachment portion rearward of the front wheel in the direction of travel and forward of the bracket main body portion, and the elastic portion further comprises a first attachment portion attached to the arm at the arm attachment portion and a second attachment portion attached to the bracket main body portion, and the elastic main body portion connects the first attachment portion and the second attachment portion.

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