JP7503017B2 - Wheel device - Google Patents

Description

The present invention relates to a wheel device for mounting on a cart, wheelchair, etc.

A conventional proposal has been made to mount three pairs of wheel devices on the front, rear, and intermediate sections of a cart with a push handle. In this proposal, the wheels of the intermediate pair of wheel devices are each able to swing around an axis parallel to the rotation axis of the wheels of the rear pair of wheel devices together with the push handle of the cart via a pair of swing devices.

According to this, by swinging the push handle, the pair of wheels in the middle are swung and brought from a non-contact state to a contact state with the road surface, helping the front or rear pair of wheels overcome steps. However, the swinging device has a relatively complex structure, and the installation of the swinging device requires significant modification of the dolly.

JP 2014-80068 A

The present invention provides a new wheel device that can be attached to a cart, wheelchair, etc., and enables the vehicle to overcome obstacles such as steps.

The wheel device according to the present invention comprises a mounting member having a mounting part with a flat mounting surface to be attached to a mounting object such as a dolly or wheelchair and an axle connected to the mounting part, a receiving member that receives the mounting member at the mounting part, the receiving member having a through hole through which the axle of the mounting member passes and is rotatable around the axle, two pairs of wheels having rotation axes attached to the receiving member at intervals around a center line passing through the axle, and a movement limiting member that is attached to the axle and limits the movement of the receiving member along the axle. The two pairs of wheels are on two opposing side surfaces of a quadrangular pyramid having an axis on the center line and a rectangular base whose center is on the center line and are in contact with the base, and the rotation axes of each pair of wheels are perpendicular to the two side surfaces. When a plane including the rotation axes of one pair of wheels out of the two pairs of wheels is parallel to the mounting surface of the mounting part, the pair of wheels is in a state in which it can roll on the road surface.

In the present invention, the term "wheel" conceptually refers to both a wheel consisting of one wheel and a wheel consisting of multiple wheels, including a double wheel. Therefore, with regard to the "number of wheels" in the present invention, the number of wheels consisting of one wheel and the number of wheels consisting of multiple wheels are both "1."

The wheel devices are attached, for example, two at each end to the front and rear of the dolly. When the dolly is placed on the road surface, one pair of the two pairs of wheels of the wheel device (hereinafter referred to as a pair of wheels) comes into contact with the road surface and is placed in a state in which it can roll on the road surface around its rotation axis, and the dolly is placed in a state in which it can run on the road surface. The weight of the dolly and the load of the luggage loaded on the dolly (load) are transmitted to the pair of wheels via the mounting members and the receiving members.

The cart can travel on the road surface via the pair of wheels of each wheel device. When the cart is traveling and there is an obstacle to its travel ahead in the direction of travel, such as a step protruding upward, one of the pair of wheels of each wheel device, which is the front wheel that hits the obstacle, receives a relatively large resistance, and as a result, the support member receives a relatively large rotational external force that tries to rotate it around the axle of the mounting member. As a result, the support member begins to rotate around the axle, and when the rotation angle reaches 90 degrees, the other pair of wheels straddles the step, and one of the other pair of wheels lands. When the rotation angle reaches 180 degrees through continued rotation, the other pair of wheels is placed in a state in which it can roll on the road surface, and the step is overcome.

As an example, the mounting member may have a conical surface of a convex truncated cone tapering toward the receiving member, and the receiving member may have a recess connected to its through hole that allows the shaft to pass through. Here, the recess has a conical surface of a concave truncated cone that is the same shape as the convex truncated cone, and the conical surface of the mounting member and the conical surface of the receiving member are in contact with each other. In this way, when the receiving member rotates around the shaft, the conical surface of the receiving member slides on the conical surface of the mounting member. Instead of this example, the mounting member and the receiving member may have two flat surfaces that face each other and are in contact with each other. In this way, when the receiving member rotates around the shaft, the flat surface of the receiving member slides on the flat surface of the mounting member.

FIG. 2 is a perspective view showing a carriage and a wheel device attached thereto. 1 is a perspective view of a wheel device in a state in which a pair of wheels are capable of rolling on a road surface. FIG. 11 is a perspective view of the wheel device when another pair of wheels is placed in a state capable of rolling on a road surface. FIG. 1 is a partial front view of the front part of the platform of a dolly to which a wheel device is attached, in which one pair of wheels of the wheel device is placed in a state in which it can roll on a road. 4 is an enlarged cross-sectional view showing a portion of the mounting member and the receiving member. FIG. FIG. FIG. FIG. 1 is a partial side view of the front of a platform of a dolly to which a wheel device is attached, showing a state in which one wheel (front wheel) of two pairs of wheels of the wheel device collides with a step when the dolly is traveling on a road surface. 1 is a partial side view of the front part of the platform of a dolly to which a wheel device is attached, showing a state in which a pair of wheels of the wheel device are in the middle of climbing over a step and the rotation angle of the support member and the two pairs of wheels around the axle has reached 45 degrees. 1 is a partial side view of the front part of the platform of a dolly to which a wheel device is attached, showing a state in which a pair of wheels of the wheel device are in the middle of climbing over a step and the rotation angle of the support member and the two pairs of wheels around the axle has reached 90 degrees. 1 is a partial side view of the front part of the platform of a dolly to which a wheel device is attached, showing a state in which a pair of wheels of the wheel device are in the middle of climbing over a step and the rotation angle of the support member and the two pairs of wheels around the axle has reached 135 degrees. 1 is a partial side view of the front part of the platform of a dolly to which a wheel device is attached, showing a state in which the wheel device has completed climbing over a step, i.e., the rotation angle of the support member and two pairs of wheels around the axle has reached 180 degrees, and the other pair of wheels of the wheel device is ready to roll on a road surface.

Referring to FIG. 1, the wheel device according to the present invention is indicated by the reference numeral 10. In the figure, two pairs of wheel devices 10 are attached to a plate-shaped loading platform 14 of a dolly 12, which is an example of an object to which the wheel devices 10 are to be attached, as a pair of front wheels and a pair of rear wheels of the dolly 12. The dolly 12 travels on a road surface R via the two pairs of wheel devices 10 when pushed by hand using a push handle 16 provided at the rear end of the dolly 12. The wheel devices 10 can be attached to a wheelchair, for example, and used as the front wheels of the wheelchair.

As shown in Figures 2 to 4, the wheel device 10 includes a mounting member 18 that is attached to the trolley 12, a support member 20 that receives the mounting member 18, and two pairs of wheels 22, 24 that are attached to the support member 20.

The mounting member 18 has a mounting portion 26 and a shaft portion 28 connected to the mounting portion 26.

As shown in FIG. 5, the mounting portion 26 has an upper portion 30 located at the top of the figure, and a lower portion 32 located below the upper portion. The upper portion 30 has a flat mounting surface 34. The wheel device 10 is mounted to the dolly 12 with the mounting surface 34 of the upper portion 30 in contact with the flat underside of the loading platform 14 of the dolly 12.

The lower portion 32 of the mounting portion 26 has a conical surface 32a that defines a convex truncated cone that tapers downward from the upper portion 30, i.e., toward the receiving member 20, and a circular bottom surface 32b located at the tip of the conical surface. The shaft portion 28 extends downward from the bottom surface 32b of the lower portion 32 in the figure. The shaft portion 28 shown has a circumferential groove 29 provided at its tip.

On the other hand, the receiving member 20 that receives the mounting member 18 has a through hole 36 through which the shaft portion 28 of the mounting member 18 passes, and is rotatable around the shaft portion 28. The receiving member 20 shown in the figure has a receiving portion 38 that is generally cylindrical in shape, and four arm portions 40 that are fixed to the receiving portion 38 and extend diagonally downward in the figure. The four arm portions 40 are arranged at intervals from one another around the axis of the through hole 36. Here, the axis of the through hole 36 is substantially on the center line L that passes through the shaft portion 28, or more precisely, on the center line L of the wheel device 10 that extends along the axis of the shaft portion 28.

The receiving portion 38 has a recess 42 that communicates with the through hole 36 and allows the shaft portion 28 to pass through. The recess 42 has a conical surface 42a that defines a concave truncated cone of the same shape as the convex truncated cone, which extends and opens out toward the mounting portion 26. The recess 42 of the receiving portion 38 receives the lower portion 32 of the mounting portion 26, and the conical surface 32a of the lower portion 32 of the mounting portion 26 contacts the conical surface 42a of the recess 42. As a result, when the mounting member 18 is received by the receiving member 20 at its mounting portion 26 and the receiving member 20 rotates around its shaft portion 28 relative to the mounting member 18, the conical surface 42a of the receiving portion 38 slides on the conical surface 32a of the mounting portion 26.

Instead of the illustrated example in which the mounting portion 26 is provided with the convex truncated cone-shaped lower portion 32 and the receiving portion 38 is provided with the concave truncated cone-shaped recess 42, the mounting portion 26 and the receiving portion 38 can each have two flat surfaces (not shown) that face each other and are in contact with each other, without providing the lower portion 32 and recess 42. In this way, when the receiving member 20 rotates around the shaft portion 28, the flat surface of the receiving portion 38 slides on the flat surface of the mounting portion 26.

The wheel device 10 further includes a movement limiting member 44 that is attached to the shaft portion 28 and limits the movement of the receiving member 20 along the shaft portion 28. The illustrated movement limiting member 44 is made of a C-ring fitted into the circumferential groove 29 of the shaft portion 28. In the illustrated example, in addition to the movement limiting member 44, a coil spring 46 as a cushioning means surrounding the periphery of the shaft portion 28 and a washer 48 that receives the coil spring are disposed between the receiving portion 38 and the movement limiting member 44.

Referring again to Figures 2 to 4, each wheel 22 and each wheel 24 is rotatably supported by each fork 50 via an axle 52. The two forks 50 supporting each pair of wheels 22, 24 are fixed to a belt-shaped connecting plate 54 and connected to each other. The pair of wheels 22 and the other pair of wheels 24 are supported by two of the four arm portions 40 and the other two arm portions 40 via the two connecting plates 54, respectively.

6 to 8, the two pairs of wheels 22, 24 are located on two opposing side surfaces P3 of a pyramid P having a rectangular base P2 and an axis P1 that is the center line L passing through the shaft portion 28. Furthermore, a rotation axis ₁₁ passing through the axles 52 of the pair of wheels 22 and a rotation axis ₁₂ passing through the axles 52 of the other pair of wheels 24 are perpendicular to both side surfaces P3. Therefore, the pair of wheels 22 and the other pair of wheels 24 face each other at an angle to each other, and the pair of wheels 22 and the other pair of wheels 24 face the same direction.

The pyramid P forms a right pyramid with a perpendicular line (axis P1) extending from its vertex P4 toward the rectangular base P2 passing through the center of gravity (center) of the base P2, and the four hypotenuses (ridges) of the pyramid P extend along the four arms 40. The pyramid P preferably has a rectangular base P2 that approximates a square, as in the illustrated example, and more preferably has a square base P2. Most preferably, the pyramid P has a square base P2 and each hypotenuse has a length equal to the length of one side of the square.

Furthermore, each of the pair of wheels 22 and the other pair of wheels 24 can be made up of a single wheel as shown, or multiple wheels including double wheels (not shown). Here, the number of each wheel 22, 24 is considered to be 1, regardless of whether each wheel 22, 24 is made up of a single wheel or multiple wheels.

Referring again to Fig. 4, the wheel device 10 is attached to the platform 14 of the cart 12 so that either one of the two pairs of wheels 22, 24 (the pair of wheels 22 in the drawing) can roll on the road surface R. More specifically, the wheel device 10 is attached so that the pair of wheels 22 can roll on the road surface R when a plane _H1 (see Fig. 9) including the two axes _l1 of the pair of wheels 22 of the wheel device 10 and a flat mounting surface 34 of the mounting portion 26 are parallel to each other, and the wheel device 10 is attached so that the pair of wheels 24 can roll on the road surface R when a plane H2 (see Fig. 13) including the two axes _l2 of the other pair of wheels ₂₄ and a mounting surface 34 of the mounting portion 26 are parallel to each other. For this attachment, in the illustrated example, an angle α is set between the center line L of the shaft portion 28 and the mounting surface 34 of the mounting portion 26. The value of the angle α varies depending on the shape of the pyramid P, more specifically, the shape of the base P2 and the size of the hypotenuse of the pyramid P, and is determined by geometric calculations. In the most preferred example of the pyramid P, the angle α is about 55 degrees.

The cart 12 can travel on the road surface R via one of the two pairs of wheels 22, 24 of each wheel device 10 (the pair of wheels 22 in the figure). As shown in FIG. 9, when the cart 12 is traveling and there is an obstacle to its progress, such as a step S protruding upward, in front of the cart 12, the wheel located at the front of the pair of wheels 22 of each wheel device 10, which is the front wheel that hits the step, receives a relatively large resistance. As a result, the receiving member 20 receives a relatively large external rotational force that tries to rotate it around the shaft portion 28 of the mounting member 18.

As a result, the support member 20 and the two pairs of wheels 22, 24 begin to rotate around the shaft 28, and as a result, one wheel located at the rear of the pair of wheels 22 rotates and moves above the road surface R while one wheel located at the front of the pair of wheels 22 is in contact with the ground (Figure 10). Next, when the rotation angle of the support member 20 and the two pairs of wheels 22, 24 reaches 90 degrees, the other pair of wheels 24 straddles the step S, and the one wheel located at the front of the other pair of wheels 24 lands on the road surface R (Figure 11). Furthermore, as the support member 20 and the two pairs of wheels 22, 24 continue to rotate, the pair of wheels 22 rotates and moves above the road surface R while the front wheel of the other pair of wheels 24 remains in contact with the road surface R (Figure 12). During this time, the loading platform 14 of the dolly 12 is raised. Furthermore, when the rotation angle reaches 180 degrees, the other pair of wheels 24 contacts the road surface R and is able to roll on the road surface R, completing the climb over the step S (Figure 13). During this time, the height position of the platform 14 gradually drops to the height position shown in Figure 9.

10 Wheel device 12 Cart (mounting object)
18 Mounting member 20 Receiving member 22 Pair of wheels 24 Another pair of wheels 26 Mounting portion 28 Shaft portion 38 Receiving portion 42 Recess 44 Movement limiting member 46 Coil spring L Center line l ₁ , 1 ₂ Rotation axis of wheel

Claims (5)

A wheel device comprising:
a mounting member having a mounting portion having a flat mounting surface to be attached to an object to which the wheel device is to be attached and a shaft portion connected to the mounting portion;
a receiving member for receiving the mounting member, the receiving member having a through hole through which a shaft portion of the mounting member is inserted and being rotatable around the shaft portion;
two pairs of wheels having rotation axes attached to the receiving member at intervals around a center line passing through the axle, the wheels being on two opposing side surfaces of a quadrangular pyramid having an axis on the center line and a rectangular base whose center is on the axis line and in contact with the base, and the rotation axes of the two pairs of wheels are each perpendicular to the two side surfaces;
a movement limiting member attached to the shaft portion and limiting movement of the receiving member along the shaft portion,
A wheel device in which, when a plane including the rotation axes of one of the two pairs of wheels is parallel to the mounting surface of the mounting portion, the pair of wheels is placed in a state in which it can roll on a road surface. The mounting member has a conical surface of a convex truncated cone tapering toward the receiving member, the receiving member has a recess that allows the shaft portion to pass through and is connected to the through hole, and the recess has a conical surface of a concave truncated cone that is the same shape as the convex truncated cone,
The wheel assembly according to claim 1 , wherein the conical surface of the mounting member and the conical surface of the receiving member are in contact with each other. The wheel device according to claim 1, wherein the mounting member and the receiving member have two flat surfaces that face each other and are in contact with each other. The wheel device according to any one of claims 1 to 3, wherein the mounting object is a bogie. The wheel device according to any one of claims 1 to 3 , wherein the object to which the wheel device is to be attached is a wheelchair.

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