JP7479600B2 - Step-crossing aid and wheeled transport device equipped with the aid - Google Patents

Description

The present invention relates to a step-over-step assistance device that assists a wheeled transport device in overcoming a step, and to a wheeled transport device equipped with the step-over-step assistance device.

Conventionally, as an auxiliary device for getting over a step and a wheeled transport device equipped with the same, a wheelchair with a step-over function disclosed in Patent Document 1 is known. When this wheelchair is going over a step, the auxiliary wheels are placed on the ground by stepping on the operation link of the four-side connecting link with the foot, and the front wheels (steering wheels) of the wheelchair can be lifted by applying a stepping force to the operation link. The four-side connecting link is locked when the steering wheels are lifted to a certain extent, so that the steering wheels can be moved and positioned above the step by pushing the wheelchair forward in this state. Then, when the auxiliary wheels are returned to their original positions by releasing the lock on the four-side connecting link, the steering wheels are placed on the ground above the step.

JP 10-85264 A

In the above-mentioned conventional wheelchair, the steering wheels can be lifted up over a step by the action of the four-side link and the auxiliary wheels, but in order to move the steering wheels over the step, the caregiver must push the wheelchair forward. Since the operation of lifting the steering wheels and the operation of moving the wheelchair forward are required, the conventional wheelchair has a problem that it is time-consuming to get over a step. In addition, after the auxiliary wheels touch the ground, if the wheelchair is not supported firmly, the auxiliary wheels may rotate in the direction of moving the wheelchair backward. Furthermore, since the four-side link is used to support the auxiliary wheels, the structure of the step-crossing assistance mechanism becomes complicated, and the wheelchair equipped with this mechanism becomes heavy. Since wheelchairs are often folded and carried, the increased weight is a heavy burden for the caregiver.

The present invention has been created in view of the above problems, and aims to provide a step-crossing aid that makes it easier to get over steps, and a wheeled transport device equipped with the same. To achieve this aim, the step-crossing aid of the present invention has a lever member that is arranged to extend in the direction of travel of a wheeled transport device such as a wheelchair or a luggage transport cart, the lever member is rotatably supported on a base member that can be attached to the wheeled transport device, and a movable fulcrum member is rotatably connected to the lever member at a predetermined position away from the center of rotation, and the movable fulcrum member is always opposed to the running surface of the wheeled transport device and has a cam surface that extends in the direction of rotation of the movable fulcrum member.

When force is applied to the lever member to rotate it relative to the base member, the cam surface of the movable fulcrum member comes into contact with the running surface of the wheeled transport device, which becomes the fulcrum of the lever. When further force is applied to the lever member to rotate it, the connection point between the base member and the lever member is lifted with the movable fulcrum member as the fulcrum, due to the principle of leverage. At the same time, the movable fulcrum member rotates so that the cam surface moves along the running surface, and the wheeled transport device moves forward while the front wheels are lifted. This makes it easier for the wheeled transport device to overcome steps.

The movable fulcrum member is preferably configured to be rotatable in a direction to advance the wheeled transport device. Moreover, the movable fulcrum member is preferably arranged so that a cam surface on the rear side of the wheeled transport device from the rotation center of the movable fulcrum member contacts the running surface as the lever member rotates. By configuring the cam surface on the rear side of the rotation center to contact the running surface, the movable fulcrum member can be reliably rotated in the direction to advance the wheeled transport device.

Furthermore, it is preferable that the cam surface of the movable fulcrum member is configured such that the length from the portion in contact with the running surface to the center of rotation of the movable fulcrum member becomes shorter as the movable fulcrum member rotates. Moreover, it is preferable that the cam surface of the movable fulcrum member is formed as a smooth curved surface over its entire length. By configuring the cam surface in this way, even if the lever member rotates further as the movable fulcrum member rotates, the front wheel of the wheeled transport device does not lift more than necessary. In other words, it is possible to minimize the inclination of the wheeled transport device when going over a step. As a result, if the wheeled transport device is a wheelchair for carrying a person, the wheelchair will not tilt more than necessary, causing fear to the person riding in it.

The same effect as described above can also be obtained by a wheeled transport device equipped with the step-crossing aid. That is, a wheeled transport device that can cross steps more reliably and more easily with the step-crossing aid can be provided. Suitable examples of such wheeled transport devices include wheelchairs and luggage carriers.

According to the present invention, the action of the lever member and the movable fulcrum member makes it easier for a wheeled transport device such as a wheelchair or a baggage transport cart to overcome a step. In addition, when the lever member rotates and the movable fulcrum member comes into contact with the running surface of the wheeled transport device, the force that rotates the lever member thereafter is immediately converted into a force that lifts the wheels and a force that rotates the movable fulcrum member to move the wheeled transport device forward, so that the wheels of the transport device can be lifted and moved forward at the same time, and it is no longer necessary to overcome a step as in the past. In addition, there is an advantage that the complicated link mechanism found in the conventional step-crossing aid is no longer necessary, and the configuration is simplified to minimize the weight increase when attached to a wheeled transport vehicle. This weight reduction is a great advantage in that it reduces the burden on the caregiver who carries the wheelchair, which is often folded and carried when not in use.

1 is a cross-sectional view of a wheelchair equipped with a step-crossing aid according to the present invention. 1 is a rear view of a wheelchair equipped with a step-crossing aid according to the present invention; FIG. 2 is a right side view of the step-crossing aid according to the present invention. FIG. 2 is a left side view of the step-crossing aid according to the present invention. 1 is a plan view of a step-crossing aid according to the present invention. 1 is an enlarged view illustrating the operation of a main part of a wheelchair equipped with a step-crossing aid according to the present invention; 1 is an explanatory diagram of the operation of a wheelchair equipped with a step-crossing aid according to the present invention; 1 is an explanatory diagram of the operation of a wheelchair equipped with a step-crossing aid according to the present invention; 1 is a cross-sectional view of a luggage transport cart equipped with a step-crossing aid according to the present invention. 1 is a bottom view of a luggage transport cart equipped with a step-crossing aid according to the present invention. FIG. FIG. 11 is a right side view of another step-crossing aid according to the present invention. FIG. 11 is a rear view of another step-crossing aid according to the present invention.

Hereinafter, an embodiment of the invention will be described. In Fig. 1 to Fig. 8, reference numeral 10 denotes a step-crossing aid, and in Fig. 1 and Fig. 2, reference numeral 20 denotes a wheelchair, which is an example of a wheeled transport device equipped with the step-crossing aid 10.

The step-crossing aid 10 is particularly configured to assist a pair of front wheels 21 provided at the front of a wheelchair 20 in climbing over steps. The wheelchair 20 is provided with X-shaped cross members 23, 24 at the front and rear below the seat 22, and is configured to be foldable by rotating the cross members 23, 24. In other words, the members 23a, 23b, 24a, 24b constituting the cross members 23, 24 are each rotatably connected to the body frames 25, 26 on the sides of the wheelchair 20, and the intersections between the members are also rotatably connected.

The step-crossing aid 10 is attached to the cross members 23, 24 of the wheelchair 20 so as to hang down from them. The step-crossing aid 10 has a square bar-shaped base member 11 extending in the direction of travel of the wheelchair 20 below the cross members 23, 24, and support parts 11a, 11b are integrally provided in an upright manner at the front and rear of the base member 11. The base member 11 is attached to the wheelchair 20 by fastening the support parts 11a, 11b together to the cross-connecting points of the members 23a, 23b, 24a, 24b of the cross members 23, 24, respectively.

One end of a square bar-shaped lever member 12 is rotatably supported on the front end of the base member 11, and a sector-shaped movable fulcrum member 13 is rotatably supported on a predetermined position midway in the longitudinal direction of the lever member 12. Both the lever member 12 and the movable fulcrum member 13 are configured to be rotatable on a plane that is parallel to the front-rear direction of the wheelchair 20 and perpendicular to the running surface of the wheelchair. The other end of the lever member 12 is positioned to extend downward to the rear of the seat surface 22 of the wheelchair 20, and a plate-shaped pedal 14 is fixed thereto. Furthermore, the lever member 12 is connected to the base member 11 by a spring 15 so as to be constantly kept rotated toward the base member 11. The spring 15 is configured to be hung on a spring hook 11c provided on the support portion 11b of the base member 11, and the spring hook 11c can be replaced with a plurality of mounting holes 11d... provided in the longitudinal direction of the support portion 11b. With this configuration, the force pulling the lever member 12 can be changed by changing the position of the spring hook 11c.

The movable fulcrum member 13 has a cam surface 13a consisting of a smooth arc-shaped curved surface with a uniform radius, and rubber 16 is attached to the entire surface of this cam surface 13a for the purpose of protection and anti-slip (in the following explanation, this rubber 16 is also referred to as the cam surface 13a). The movable fulcrum member 13 is constantly pulled by a spring 17 stretched between it and the lever member 12, so that the cam surface 13a faces the front side of the wheelchair 20 and one end of the cam surface 13a faces the running surface of the wheelchair 20, and is constantly maintained in a rotated state toward the lever member 12.

The center of rotation of the movable fulcrum member 13, i.e., the pivot point 13b for the lever member 12, is set at a position offset by a predetermined length toward the front side of the wheelchair 20 from the center ct of the imaginary circle Cr along the cam surface 13a. Therefore, as shown in Fig. 6, the lengths r1 and r2 from each end of the cam surface 13a to the pivot point 13b are different (r1>r2). The movable fulcrum member 13 is always maintained in a rotated state so that the end of the cam surface 13a on which the length from the pivot point 13b to the cam surface 13a is longer faces the running surface of the wheelchair 20.

Next, the operation of the wheelchair 20 equipped with the step-crossing aid 10 when climbing over a step will be described. The front wheels 21 of the wheelchair 20 are usually significantly smaller in diameter than the rear wheels 27, and the wheelchair 20 cannot move forward even if there is a slight step on the running surface. In the wheelchair 20 according to the present invention, as shown in Fig. 7, when the front wheels 21 are in contact with or close to a step and a caregiver (not shown) pushing the wheelchair 20 steps on the pedal 14, the lever member 12 rotates toward the running surface with the pivot fulcrum 12a as the center of rotation, and in response, the cam surface 13a of the movable fulcrum member 13 comes into contact with the running surface.

When the pedal 14 is further depressed to rotate the lever member 12 toward the running surface, the force applied to the lever member 12 is increased accordingly, with the movable fulcrum member 13 in contact with the ground as the fulcrum, and acts on the pivot fulcrum 12a with the base member 11 (principle of leverage). As a result, a force is generated to lift the front wheel 21 of the wheelchair 20.

Furthermore, as described above, when the pedal 14 is further depressed to rotate the lever member 12, the movable fulcrum member 13 receives the force and rotates counterclockwise in Fig. 8. As the movable fulcrum member 13 rotates, i.e., as the cam surface 13a rolls forward on the running surface, the wheelchair 20 moves forward.

One end of the movable fulcrum member 13 contacts the traveling surface with the cam surface 13a facing forward, and at this time, the contact portion of the cam surface 13a is set to be a predetermined distance L behind the pivot fulcrum 13b (center of rotation) of the movable fulcrum member 13, as shown in Figure 6. Therefore, the movable fulcrum member 13 can be reliably rotated in the direction that moves the wheelchair 20 forward.

In addition, the length from the pivot 13b, which is the center of rotation of the movable fulcrum member 13, to the cam surface 13a is not uniform, so when the cam surface 13a rolls along the running surface of the wheelchair 20, the length from the pivot 13b (center of rotation) to the grounding portion of the cam surface 13a gradually shortens with the rotation of the movable fulcrum member 13. Therefore, if the amount of depression of the pedal 14 does not change, the lifted front wheel 21 will gradually lower as the wheelchair 20 moves forward. However, since the caregiver keeps his/her foot on the pedal 14, even if the wheelchair 20 moves forward with the rotation of the movable fulcrum member 13, he/she cannot take a step forward in response to this. Therefore, when the wheelchair 20 moves forward and the fulcrum moves forward, the caregiver will naturally press the pedal 14 deeper. As a result, even if the wheelchair 20 moves forward, the front wheel 21 does not lower, and it is possible to keep it at a substantially constant height. In other words, the cam surface is set to produce such a movement. If the length from the pivot 13b of the movable fulcrum member 13 to the ground contact point of the cam surface 13a did not change even when the movable fulcrum member 13 rotated, the front wheel 21 would be lifted higher if the caregiver pressed deeply into the pedal 14 as described above. In other words, the wheelchair 20 would be significantly tilted backward, and in severe cases, this could cause fear to the user sitting in the wheelchair 20.

As described above, by depressing the pedal 14 of the lever member 12, the wheelchair 20 can be moved forward while lifting the front wheel 21, and thus the front wheel 21 of the wheelchair 20 can be moved up the step as shown in Fig. 8. Then, when depressing the pedal 14 is stopped, the lever member 12 and the movable fulcrum member 13 are rotated back to their original positions by the forces of the springs 15 and 17, respectively, so that the front wheel 21 can land on the step. Since the diameter of the rear wheels of the wheelchair 20 is significantly larger than that of the front wheels 21, once the front wheels 21 have overcome the step, the step can be easily overcome by the assistant simply by pushing the wheelchair 20.

9 and 10 show a wheeled transport device according to another embodiment of the present invention, which is a luggage transport dolly 30 (hereinafter simply referred to as dolly 30) equipped with a step-crossing aid 100 based on the same principle as described above. Here, the step-crossing aid 100 has a base member 101 fastened to the dolly 30 by a bolt 31a that attaches the front wheels 31, 31 (both of which are swivel casters) of the dolly 30. The tip of a square bar-shaped lever member 102 extending rearward from the dolly 30 is pivotally supported on the base member 101, and a substantially sector-shaped movable fulcrum member 103 is pivotally supported on the lever member 102. The configurations of the lever member 102 and the movable fulcrum member 103 are substantially the same as the lever member 12 and the movable fulcrum member 13 of the step-crossing aid 10 attached to the wheelchair 20 described above, and therefore will not be described in detail here. The lever member 102 and the movable fulcrum member 103 are tensioned by springs 104 and 105 so as to be constantly maintained in a rotated state toward the loading platform 32 of the dolly 30 .

In this dolly 30, by stepping on the pedal 106 at the end of the lever member 102, the entire dolly 30 can be moved forward while applying a force to lift the front wheel 31 of the dolly 30, as in the above-mentioned wheelchair 20, and thus it is possible to easily overcome a step. In the case of the dolly 30, there is often no difference in diameter between the front wheel 31 and the rear wheel 33. In the step-crossing aid 100 of this dolly 30, the movable fulcrum member 103 is disposed between the rear wheels 33, 33, i.e., in line with the rear wheel 33, and the cam surface 103a is configured to always protrude slightly forward from the rear wheels 33, 33. Moreover, the movable fulcrum member 103 can rotate against the tensile force of the spring 105 even without the force being applied from the lever member 102, and the rotation radius is larger than the rotation radius of the rear wheel 33. Due to this configuration, the rear wheel 33 side can overcome a step just by pushing the dolly 30 without stepping on the pedal 106. In other words, if the dolly 30 is pushed without depressing the pedal 106 after the front wheel 31 has climbed up the step, the movable fulcrum member 103, which has returned to the loading platform 32 side by the force of the spring 105, will come into contact with the step at the cam surface 103a before the rear wheel 33 reaches the step. If the dolly 30 is pushed further from here, the movable fulcrum member 103 will receive the force and rotate around the contact point between the step and the cam surface 103a as a fulcrum. As a result, the dolly 30 moves forward with the rear wheel 33 being lifted, and the rear wheel 33 can also get over the step with less force.

11 and 12 show a step-crossing aid 10' according to another embodiment of the present invention, in which a roller 18 is attached to the rear end of the lever member 12 so as to be rotatable in the forward and backward directions of the wheeled transport device. By providing such a roller 18, as shown in FIG. 8, even if the wheelchair 2 or the like is tilted or the lever member 12 is pressed deeply when crossing a step, the roller 18 rolls in contact with the running surface, protecting the lever member 12 and enabling smooth step-crossing. In addition, this step-crossing aid 10' is configured such that the base member 11 is divided at each connecting portion of the support portions 11a and 11b, and these portions are made into hinge-like pivot structures, so that the lever member 12 and the movable pivot member 13 can be rotated together about the pivot points 19a and 19b. Of course, although not shown, it is desirable to provide a stopper structure so that the lever member 12 etc. can be maintained in the positions shown in Fig. 12(a) and Fig. 12(b). By making the lever member 12 etc. rotatable in this way, when the step-crossing aid 10' is not needed, the lever member 12 and the movable fulcrum member 13 etc. can be rotated to the position shown in Fig. 12(b), allowing more space on the running surface side of the wheelchair 20 or the cart 30.

In the step-crossing aid 10' shown in Figures 11 and 12, the spring 15 is removed to prevent the spring 15 from twisting when the lever member 12 and the like are rotated to the position shown in Figure 12(b). However, if the pivot point 19b is positioned above the spring hook 11c, it is possible to rotate the lever member 12 and the like without removing the spring 15.

The above explanation has presented examples in which the step-crossing aid is applied to a wheelchair 20 and a luggage transport cart 30, but the step-crossing aid of the present invention can be applied to various wheeled transport devices equipped with wheels for movement, such as other types of carts, pushcarts, carts, factory automation equipment and home appliances with casters, wheeled stretchers, and wheeled beds.

REFERENCE SIGNS LIST 10 Step-crossing aid 10' Step-crossing aid 11 Base member 12 Lever member 13 Movable fulcrum member 13a Cam surface 13b Pivot 14 Pedal 15 Spring 16 Rubber 17 Spring 18 Roller 19a, 19b Pivot 20 Wheelchair 21 Front wheel 22 Seat 23, 24 Cross member 25, 26 Body frame 27 Rear wheel 30 Luggage transport cart 31 Front wheel 32 Cargo platform 33 Rear wheel 100 Step-crossing aid 101 Base member 102 Lever member 103 Movable fulcrum member 103a Cam surface 104 Spring 105 Spring 106 Pedal

Claims (8)

A step-crossing aid comprising a lever member extending in the direction of travel of a wheeled transport device, the lever member being rotatably supported on a base member that can be attached to the wheeled transport device, and a movable fulcrum member being rotatably connected to a predetermined position away from the center of rotation of the lever member, the movable fulcrum member always facing the running surface of the wheeled transport device and having a cam surface extending in the direction of rotation of the movable fulcrum member. 2. The step-crossing aid according to claim 1, wherein the movable fulcrum member is configured to be rotatable in a direction in which the wheeled transport device moves forward. A step-crossing aid as described in claim 1 or claim 2, characterized in that the movable fulcrum member is positioned so that, as the lever member rotates, the cam surface that is rearward of the wheeled transport device from the center of rotation of the movable fulcrum member first comes into contact with the running surface. A step-crossing aid as described in any one of claims 1 to 3, characterized in that the cam surface of the movable fulcrum member is configured so that the length from the portion where it contacts the running surface to the center of rotation of the movable fulcrum member becomes shorter as the movable fulcrum member rotates. 5. The step-crossing aid according to claim 1, wherein the cam surface of the movable fulcrum member is formed into a smooth curved surface over its entire length. A wheeled transport device comprising the step-crossing aid according to any one of claims 1 to 5. 7. The wheeled transport device equipped with the step-crossing aid according to claim 6, wherein the wheeled transport device is a wheelchair. 7. The wheeled transport device equipped with the step-crossing aid according to claim 6, wherein the wheeled transport device is a luggage transport dolly.

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