JP2024054745A - Wheelchair anti-tipping device - Google Patents

Abstract

[Problem] To provide a wheelchair tipping prevention device of a new structure that can prevent both forward and lateral tipping of the wheelchair while minimizing adverse effects on the wheelchair's travel. [Solution] A wheelchair tipping prevention device 10 is attached to a wheelchair 12 equipped with a front caster 16 whose steering axle 28 is positioned offset in the wheel travel direction from the wheel axle 24, and has a ground contact part 54 that is supported by the fork part 22 of the front caster 16 that is rotatable about the steering axle 28, and prevents the wheelchair 12 from tipping over by contacting the ground outboard in the wheel travel direction from the ground contact position of the front caster 16. [Selected Figure] Figure 1

Description

The present invention relates to a tip-over prevention device that prevents a wheelchair from tipping over.

The number of wheelchair users is increasing due to the recent aging of the population, and as a result, the number of falls occurring while using wheelchairs is becoming an issue. Specifically, forward falls can occur when the user applies weight to the front of the wheelchair, and sideways falls can occur when the user leans out to the side from the wheelchair, so there is a need to prevent these falls.

For example, JP 2018-158001 A (Patent Document 1) proposes a wheelchair tipping prevention device that is attached to the footrest of a wheelchair to prevent the wheelchair from tipping forward. Patent Document 1 has a structure in which a leg member made of a tightly wound helical spring is provided to extend downward from the footrest. When the wheelchair is about to tip forward, the leg member braces itself against the ground, preventing the wheelchair from tipping forward.

JP 2018-158001 A

However, after the inventors' investigations, they found that the anti-tip device in Patent Document 1 only prevents the wheelchair from tipping forward or backward, and cannot prevent it from tipping sideways.

The problem to be solved by this invention is to provide a wheelchair anti-tip device with a new structure that can prevent the wheelchair from tipping over both forward and sideways.

The following describes preferred embodiments for understanding the present invention. However, each embodiment described below is merely an example, and may be combined with one another as appropriate. The multiple components described in each embodiment may be recognized and used independently as far as possible, and may also be combined with any of the components described in another embodiment as appropriate. As a result, the present invention is not limited to the embodiments described below, and various alternative embodiments may be realized.

The first aspect is a wheelchair tip-over prevention device that is attached to a wheelchair equipped with front casters whose steering axles are offset in the wheel travel direction from the wheel axles, and has a ground contact part supported by the fork part of the front casters that can rotate around the steering axle, and the ground contact part contacts the ground outside the ground contact position of the front casters in the wheel travel direction, thereby preventing the wheelchair from tipping over.

While a wheelchair tips forward and to the side, this is caused by a moment centered on an axis (tipping moment axis) that passes through the ground contact point of the front caster, the inventor discovered that an offset between the steering axis and the wheel axis of the front caster increases the distance from the point of application of the force that causes the tipping to the tipping moment axis, making the wheelchair more likely to tip in the direction of travel of the front caster (wheel travel direction). Therefore, the tipping prevention device of this embodiment is provided with a contact part that is located further in the wheel travel direction than the ground contact point of the front caster, and the contact of the contact part can prevent the wheelchair from tipping in the wheel travel direction.

The anti-tip device has a ground contact part supported by the fork part of the front caster, which rotates around the steering axis together with the wheel of the front caster, and the position of the ground contact part is always maintained in the direction of travel of the wheel of the front caster. Therefore, the ground contact part can prevent the wheelchair from tipping over not only when the wheel of the front caster is moving in the forward direction of the wheelchair, but also when the wheel of the front caster is moving to the side of the wheelchair. According to the inventor's study, a sideways tipping of a wheelchair can occur when the front caster falls to the side while the wheel of the front caster is moving in the forward direction of the wheelchair, but it was found that a sideways tipping of a wheelchair often occurs when, for example, the user leans out to the side, inputs a load to the wheelchair in the direction of travel of the wheel of the front caster to the side of the wheelchair, and then applies a force again in the same direction. Therefore, the anti-tip device of this embodiment, which can prevent the wheelchair from tipping in the direction of travel of the front caster wheels, can effectively prevent the wheelchair from tipping forward and sideways.

In the second aspect, in the fall prevention device described in the first aspect, the ground contact portion is configured with an auxiliary caster that contacts the ground at a position offset in the wheel travel direction from the front caster when the wheelchair is in a traveling state.

With a tip-over prevention device constructed according to this embodiment, the auxiliary casters are always in contact with the ground, so it is possible to prevent the wheelchair from changing position (tilting) when it tips over. In addition, because the parts that come into contact with the ground are the auxiliary casters, the wheelchair's movement is less affected even if it is always in contact with the ground.

The third aspect is the fall prevention device described in the first aspect, in which the ground contact portion is disposed close to and above the ground at a position offset in the wheel travel direction from the front caster when the wheelchair is in a traveling state.

With a tip-over prevention device constructed according to this aspect, the contact part is away from the ground when the wheelchair is moving, so the contact part is less likely to affect the movement of the wheelchair. In addition, because the contact part is disposed close to the ground, when an input that may cause tip-over is made, the contact part quickly touches the ground, effectively preventing the wheelchair from tipping over.

The fourth aspect is an anti-toppling device according to any one of the first to third aspects, in which a pair of fixing members are provided to clamp the fork portion of the front caster from both sides in the extension direction of the wheel axle and fix the fork portion, and the ground contact portion is supported by the fork portion via the pair of fixing members.

An anti-tip device constructed in accordance with this aspect is attached to the front caster by a pair of fixing members that clamp the fork section, making it possible to attach it to front casters of various sizes and structures.

The fifth aspect is a fall prevention device according to the fourth aspect, in which a pair of extension members extending forward in the wheel travel direction from the pair of fixed members are fixed to the pair of fixed members, and the ground contact portion is provided at the extension end of the pair of extension members.

With a tip-over prevention device constructed according to this aspect, the ground contact part can be placed wherever necessary without restricting the shape or size of the fixing member. In addition, because the fixing member and the extension part are separate, it is possible to change the position of the ground contact part while using a common fixing member, for example, by replacing the extension part.

The sixth aspect is an anti-tip device according to the fourth or fifth aspect, which is provided with an adjustment mechanism for adjusting the mounting position of the fixing member relative to the front caster.

With a tip-over prevention device constructed according to this aspect, for example, the attachment position of the fixing member relative to the front caster can be adjusted using an adjustment mechanism depending on the size, structure, position, etc. of the front caster, thereby adjusting the position of the contact part, etc.

The seventh aspect is a tip-over prevention device according to any one of the first to sixth aspects, in which an auxiliary grounding part is provided on the side of the front caster, and the front caster is prevented from tipping sideways by the auxiliary grounding part touching the ground.

For example, when a lateral force is applied, the wheels may get caught on uneven ground, preventing the front casters from rotating around the steering axis, causing the front casters to tilt to the side, resulting in the wheelchair tipping over to the side. With a tip-prevention device constructed in accordance with this aspect, the auxiliary grounding parts provided on the sides of the front casters prevent the front casters from tipping over to the side, thereby preventing the wheelchair from tipping over to the side in the manner described above.

The present invention makes it possible to prevent the wheelchair from tipping both forward and sideways.

FIG. 1 is a right side view showing a state in which a tip-over prevention device according to a first embodiment of the present invention is attached to a wheelchair. FIG. 2 is a perspective view showing the tip-over prevention device of FIG. 1 attached to a front caster; FIG. 2 is a perspective view of the anti-tipover device of FIG. 1 attached to a front caster from a different angle; FIG. 2 is a left side view showing the anti-tipover device of FIG. 1 attached to the front caster; FIG. 2 is a plan view showing the anti-tipover device of FIG. 1 attached to a front caster; FIG. 2 is a bottom view showing the tip-over prevention device of FIG. 1 attached to the front caster; FIG. 2 is a perspective view of a fixing member constituting the fall prevention device shown in FIG. FIG. 2 is a perspective view of a connecting member constituting the anti-toppling device shown in FIG. FIG. 2 is a bottom view model diagram illustrating how the anti-tip device shown in FIG. 1 prevents the wheelchair from tipping forward. FIG. 2 is a bottom view model diagram illustrating the prevention of a wheelchair from tipping over sideways by the tipping prevention device shown in FIG. 1. FIG. 11 is a right side view showing a state in which a tip-over prevention device according to a second embodiment of the present invention is attached to a wheelchair. FIG. 12 is a perspective view showing the tip-over prevention device of FIG. 11 attached to the front caster; FIG. 12 is a right side view showing the tip-over prevention device of FIG. 11 attached to the front caster; FIG. 12 is a front view showing the tip-over prevention device of FIG. 11 attached to the front caster; FIG. 12 is a plan view showing the tip-over prevention device of FIG. 11 attached to the front caster;

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 shows a wheelchair anti-tip device 10 according to a first embodiment of the present invention, attached to a wheelchair 12. In the following description, the up-down direction of the wheelchair 12 generally refers to the up-down direction in Figure 1, which is the vertical up-down direction, the front-rear direction of the wheelchair 12 generally refers to the left-right direction in Figure 1, and the left-right direction of the wheelchair 12 generally refers to the direction perpendicular to the plane of the paper in Figure 1. In addition, the direction of travel of the wheels 26 of the front caster 16 (wheel travel direction), which will be described later, refers to the right in Figure 3. In the following structural description, the state in which the wheel travel direction of the front caster 16 is aligned with the front of the wheelchair 12, as a general rule, will be described.

The wheelchair 12 is equipped with a frame 14 made of steel or the like that supports the seat, and the lower end of the frame 14 is supported by front casters 16 and rear wheels 18. In addition, a foot support 20 for the user to place their feet on is provided in front of the front casters 16 at the front of the frame 14.

As shown in Figs. 2 to 6, the front caster 16 is equipped with a wheel 26 that can rotate around a wheel axle 24 supported by a fork portion 22. The fork portion 22 is bifurcated at the lower portion and extends to both sides of the wheel 26, and the lower end of the fork portion 22 supports both ends of the wheel axle 24 in a fixed manner. A steering shaft 28 is attached to the upper end of the fork portion 22 that is not bifurcated. The steering shaft 28 is rod-shaped and protrudes upward from the fork portion 22, and is rotatable relative to the fork portion 22 around its central axis. The steering shaft 28 is fixed to the mounting portion of the front caster 16 on the frame 14 of the wheelchair 12, thereby mounting the front caster 16 to the frame 14. The direction of travel of the wheel 26 of the front caster 16 can be freely changed relative to the frame 14 by rotating the fork portion 22 relative to the steering shaft 28.

As shown in FIG. 4, the steering axle 28 of the front caster 16 is offset from the wheel axle 24 by a predetermined distance D in the travel direction of the wheel 26. Because the ground contact position of the wheel 26 is vertically below the wheel axle 24, the center line of the steering axle 28 is offset from the ground contact position of the wheel 26 by D in the travel direction of the wheel. The ground contact position of the wheel 26 is offset in the travel direction of the wheel from the intersection of the line connecting the upper end of the bifurcated part of the fork section 22 and the wheel axle 24 with the ground, and a predetermined caster trail T is set. The front caster 16 has the caster trail T set by the horizontal offset between the steering axle 28 and the wheel axle 24, so that the travel direction of the wheel 26 is easily oriented in the horizontal offset direction of the steering axle 28 relative to the wheel axle 24 (to the right in FIG. 4).

The tip-over prevention device 10 is provided with a pair of fixing members 30, 30 attached to the fork portion 22 of the front caster 16. As shown in FIG. 7, the fixing member 30 is formed in a substantially trapezoidal plate shape, with both front and rear ends extending in the up-down direction and the lower end extending in the front-rear direction, and both front and rear ends perpendicular to the lower end. The lower rear end of the fixing member 30 is formed with an axle insertion hole 32 through which the wheel axle 24 of the front caster 16 is inserted, penetrating in the plate thickness direction. The lower front end of the fixing member 30 is formed with two connecting bolt holes 34, 34 penetrating in the plate thickness direction, lined up in the wheel travel direction. The upper rear end of the fixing member 30 is formed with two mounting bolt holes 36, 36 penetrating in the plate thickness direction. The mounting bolt holes 36, 36 are arranged in a line along the upper end of the fixing member 30. In addition, the fixing member 30 of this embodiment is formed with a lightening hole 40 penetrating the center part in the plate thickness direction, thereby reducing weight and reducing the forming material. As shown in FIG. 4, a longitudinal reinforcing plate 38 made of steel or the like is superimposed on the fixed member 30 to improve the rigidity of the fixed member 30 against bending deformation. The reinforcing plate 38 extends in the front-rear direction, for example, to the connecting bolt hole 34 and the axle insertion hole 32, and both front and rear ends are fixed to the fixed member 30 by the connecting bolt 47 and the wheel axle 24, which will be described later.

A connecting member 42 is provided between the opposing surfaces of the pair of fixing members 30, 30. As shown in FIG. 8, the connecting member 42 is generally formed in a triangular prism shape extending in the left-right direction as a whole, with the lower surface spreading out substantially horizontally and the upper surface being an inclined surface that slopes downward toward the wheel travel direction (forward), narrowing in the vertical direction toward the front. The connecting member 42 has a void 44 that penetrates in the vertical direction with a substantially rectangular cross section. Two connecting bolt holes 46, 46 that penetrate the left and right side walls of the void 44 are formed on both the left and right sides at the lower rear end of the connecting member 42. The connecting member 42 is arranged with its rear part sandwiched between the pair of fixing members 30, 30, and the connecting bolts 47, 47 inserted into the connecting bolt holes 46, 46 of the fixing members 30, 30 are inserted into the connecting bolt holes 46, 46 of the connecting member 42, thereby bolting the connecting member 42 to the fixing members 30, 30. The connecting member 42 is fixed to the fixed members 30, 30 and is disposed forward of the wheels 26 of the front caster 16 in the wheel travel direction. The connecting member 42 is disposed between the pair of fixed members 30, 30, and positions the tip portions of the pair of fixed members 30, 30 relative to each other. The distance between the pair of fixed members 30, 30 can also be adjusted by interposing a spacer (such as a ring that is fitted onto the connecting bolt 47) between the overlapping surfaces of the connecting member 42 and the fixed member 30.

The adjuster 48 is provided at the upper rear end of the connecting member 42 so as to protrude in an upward incline toward the opposite side (rear) from the wheel travel direction. The adjuster 48 is structured so that a flat abutment member 52 is positioned in the axial direction of an adjustment screw 50 that is screwed into the connecting member 42, and is attached in a manner that allows relative rotation in the circumferential direction. The adjuster 48 can adjust the distance between the abutment member 52 and the connecting member 42 by tightening or loosening the adjustment screw 50 relative to the connecting member 42. The abutment member 52 is pressed against the upper part of the fork part 22 of the front caster 16 from diagonally below the front side, thereby determining the position and orientation of the connecting member 42 relative to the front caster 16.

An auxiliary caster 54 is attached to the end of the connecting member 42 in the direction of wheel travel as a ground contact part. The auxiliary caster 54 is attached to the underside of the connecting member 42, and when the anti-tip device 10 is attached to the front caster 16, it can contact the ground simultaneously with the front caster 16 on the outside (forward) of the front caster 16 in the direction of wheel travel. The auxiliary caster 54 contacts the ground at a position offset to the outside of the ground contact position of the front caster 16 in the direction of wheel travel. The offset amount between the ground contact position of the auxiliary caster 54 and the ground contact position of the front caster 16 is appropriately set according to the amount of movement of the tipping moment axis required for tipping prevention, which will be described later, and is preferably set within the range of 22.5 to 27.5 mm, thereby preventing interference between the tipping prevention device 10 and the foot support 20 of the wheelchair 12 while effectively obtaining the tipping prevention effect. The auxiliary caster 54 has a steering axis 56 offset forward of the wheel axis 58, similar to the front caster 16. In addition, by adjusting the attachment position and orientation of the connecting member 42 relative to the front caster 16 using the adjuster 48, the auxiliary caster 54 can be positioned so that it can come into contact with the ground at the same time as the front caster 16.

The thus constructed anti-tip device 10 is fixedly attached to the fork portion 22 of the front caster 16 of the wheelchair 12. That is, the pair of fixing members 30, 30 arranged on the left and right outer sides of the fork portion 22 are tightened to the left and right inner sides by the wheel axle 24 of the front caster 16 inserted into the axle insertion holes 32, 32, so that the fork portion 22 is sandwiched between the pair of fixing members 30, 30 from both outer sides. Also, the mounting bolt 60 inserted into the mounting bolt holes 36, 36 of the pair of fixing members 30, 30 is arranged extending rearward from the upper part of the fork portion 22, and the abutment member 52 of the adjuster 48 attached to the connecting member 42 is pressed against the upper part of the fork portion 22 from the front. As a result, the fixing members 30, 30 are positioned and fixed to the fork portion 22, and the anti-tip device 10 is attached to the fork portion 22.

In this way, the anti-tip device 10 is attached to the front caster 16 by sandwiching the fork portion 22 of the front caster 16 between a pair of fixing members 30, 30, and by sandwiching the upper portion of the fork portion 22 front and rear between the mounting bolt 60 and the adjuster 48 (contact member 52), so it is easy to accommodate differences in the size and shape of the front caster 16 and can be attached to various front casters 16 for use. The adjuster 48 functions as an adjustment mechanism in this embodiment because it is possible to adjust the attachment position and direction of the anti-tip device 10 to the fork portion 22 by adjusting the position of the contact member 52 by the amount of tightening of the adjustment screw 50 to the connecting member 42 (the amount of protrusion from the connecting member 42).

The fixing members 30, 30 and the connecting member 42 have upper surfaces that slope downward outward in the direction of wheel travel, and are gradually narrower in the vertical direction. As a result, even if the tip-over prevention device 10 is retrofitted to the front wheel caster 16 of the wheelchair 12, it is unlikely to interfere with the structure of the wheelchair 12, such as the foot support 20, and is unlikely to adversely affect the running performance of the wheelchair 12 or the storage function of the foot support 20.

The fixing members 30, 30 and the connecting member 42 are attached to the fork section 22, so that the auxiliary caster 54 is supported by the fork section 22 via the fixing members 30, 30 and the connecting member 42. The orientation of the auxiliary caster 54 relative to the front wheel caster 16 (wheel 26) of the tip-over prevention device 10 is always maintained, and the auxiliary caster 54 is always positioned outside the wheel travel direction relative to the ground contact position of the front wheel caster 16. In short, the tip-over prevention device 10 is attached to the fork section 22 of the front wheel caster 16 so that it can rotate around the steering shaft 28, and therefore, regardless of the direction of travel of the wheel of the front wheel caster 16 relative to the wheelchair 12, the auxiliary caster 54 is always positioned outside the wheel travel direction relative to the front wheel caster 16. In this embodiment, the fixing members 30, 30 and the connecting member 42 are tapered as described above, so that the tip-over prevention device 10 is allowed to change direction to follow the front wheel caster 16 without being hindered by interference with other members.

As shown in FIG. 4, the tip-prevention device 10 attached to the front casters 16 is in contact with the ground G at the auxiliary casters 54. Because the tip-prevention device 10 has a ground contact portion formed by the auxiliary casters 54, even if the device is in contact with the ground when the wheelchair 12 is in a normal traveling state, it is unlikely to affect the traveling performance of the wheelchair 12.

By mounting the tip-prevention device 10 on the front caster 16 of the wheelchair 12, the wheelchair 12 is prevented from tipping forward, for example, when the user leans forward or stands on the foot support 20. The mechanism by which the tip-prevention device 10 prevents the wheelchair 12 from tipping forward can be understood, for example, as follows.

In a wheelchair 12 without a tip-over prevention device 10, as shown in FIG. 9, when a downward load Wp acting on the front of the wheelchair 12 causes the wheelchair 12 to tip forward, the moment center axis (tipping moment axis) of the forward tipping is a straight line connecting the grounding positions of the left and right front casters 16, 16. When the moment (Wp×Lp') around the tipping moment axis due to the downward load Wp acting on the front of the wheelchair 12 is greater than the moment (Ww×Lw') around the tipping moment axis due to the downward load Ww acting on the center of gravity of the wheelchair 12 (Wp×Lp'>Ww×Lw'), the wheelchair 12 will tip forward due to the imbalance of the moments. Therefore, by keeping the difference between the moment due to the load Ww and the moment due to the load Wp positive (Ww×Lw'-Wp×Lp'>0), the wheelchair 12 can be prevented from tipping forward.

When the tip-prevention device 10 is attached to the front caster 16 of the wheelchair 12, the wheelchair 12 touches the ground at the auxiliary caster 54, which is located further forward than the front caster 16. As a result, the tip-over moment axis of a wheelchair 12 equipped with the tip-over prevention device 10 for a forward tip-over is set forward by the distance d from the contact position of the front caster 16 to the contact position of the auxiliary caster 54, relative to the tip-over moment axis of a wheelchair 12 without the tip-over prevention device 10.

In addition, in a wheelchair 12 equipped with a tip-over prevention device 10, the distance Lw from the center of gravity of the wheelchair 12, which is the point of application of the load Ww, to the tip-over moment axis is longer by d than (Lw') in the case of a wheelchair 12 without a tip-over prevention device 10. As a result, the moment (Ww x Lw) due to the load Ww of a wheelchair 12 equipped with a tip-over prevention device 10 is greater than the moment (Ww x Lw') due to the load Ww of a wheelchair 12 without a tip-over prevention device 10.

Furthermore, in a wheelchair 12 equipped with a tip-over prevention device 10, the distance Lp from the point of application of the load Wp set at the front of the wheelchair 12 to the tip-over moment axis is shorter by d than (Lp') in the case of a wheelchair 12 without a tip-over prevention device 10. As a result, the moment (Wp x Lp) due to the load Wp of a wheelchair 12 equipped with a tip-over prevention device 10 is smaller than the moment (Wp x Lp') due to the load Wp of a wheelchair 12 without a tip-over prevention device 10.

As a result, compared to a wheelchair 12 without a tip-over prevention device 10, a wheelchair 12 equipped with a tip-over prevention device 10 has a larger moment due to load Ww acting in a direction that prevents the wheelchair from tipping forward, and a smaller moment due to load Wp acting in a direction that causes the wheelchair to tip forward. This makes it easier to keep the difference between the moment due to load Ww and the moment due to load Wp positive, thereby preventing the wheelchair 12 from tipping forward.

The tip-over prevention device 10 can also prevent the wheelchair 12 from tipping sideways. That is, when the user leans out to the side of the wheelchair 12, for example, and the user's center of gravity moves to the side of the wheelchair 12, a downward load Wp acts on the wheelchair 12 to the side, as shown in FIG. 10. Note that sideways tipping is likely to occur when the wheel direction of the front caster 16 faces the side where the load Wp acts, as shown in FIG. 10, so the following describes a state in which the load Wp acts to the right of the wheelchair 12 and the front caster 16 faces to the right of the wheelchair 12.

In a wheelchair 12 without a tip-over prevention device 10, the tip-over moment axis for lateral tip-over is a straight line extending through the ground contact position of the right rear wheel 18 and the ground contact position of the right front wheel caster 16. The right front wheel caster 16 rotates around the steering axis 28 so that the right direction of travel is the ground contact position to the left of the ground contact position of the rear wheel 18. As in the case of forward tip-over, the wheelchair 12 will tip over sideways when the moment (Wp x Lp') around the tip-over moment axis due to a downward load Wp acting on the side of the wheelchair 12 is greater than the moment (Ww x Lw') around the tip-over moment axis due to a downward load Ww acting on the center of gravity of the wheelchair 12 (Wp x Lp' > Ww x Lw'). Therefore, by keeping the difference between the moment due to the load Ww and the moment due to the load Wp positive (Ww x Lw' - Wp x Lp' > 0), the wheelchair 12 can be prevented from tipping over to the side. In other words, by making the moment due to the load Ww as large as possible and the moment due to the load Wp as small as possible, tipping over to the side can be prevented.

In a wheelchair 12 equipped with a tip-over prevention device 10, when the front caster 16 is facing right as shown in FIG. 10, the auxiliary caster 54 touches the ground to the right of the front caster 16. As a result, the tip-over moment axis of a lateral tip-over in a wheelchair 12 equipped with a tip-over prevention device 10 is set to the right and outward of the tip-over moment axis of a wheelchair 12 without a tip-over prevention device 10.

In addition, in a wheelchair 12 equipped with a tip-over prevention device 10, the distance Lw from the center of gravity of the wheelchair 12, which is the point of application of the load Ww, to the tip-over moment axis is longer than the distance (Lw') in the case of a wheelchair 12 without a tip-over prevention device 10. As a result, the moment (Ww x Lw) due to the load Ww in a wheelchair 12 with a tip-over prevention device 10 is greater than the moment (Ww x Lw') due to the load Ww in a wheelchair 12 without a tip-over prevention device 10.

In addition, in a wheelchair 12 equipped with a tip-over prevention device 10, the distance Lp from the point of application of the load Wp input to the right of the wheelchair 12 to the tip-over moment axis is shorter than that (Lp') in the case of a wheelchair 12 without a tip-over prevention device 10. As a result, the moment (Wp x Lp) due to the load Wp of a wheelchair 12 with a tip-over prevention device 10 is smaller than the moment (Wp x Lp') due to the load Wp of a wheelchair 12 without a tip-over prevention device 10.

As a result, compared to a wheelchair 12 without a tip-over prevention device 10, a wheelchair 12 equipped with a tip-over prevention device 10 has a larger moment due to the load Ww acting in a direction that prevents lateral tipping, and a smaller moment due to the load Wp acting in a direction that causes lateral tipping, making it easier to keep the difference between the moment due to the load Ww and the moment due to the load Wp positive, thereby preventing the wheelchair 12 from tipping sideways.

In this way, the anti-tip-over device 10 has the auxiliary caster 54, which is the ground contact part, rotatable around the steering shaft 28 together with the front caster 16, and is always held forward of the direction of travel of the front caster 16. Therefore, when the direction of travel of the front caster 16 faces to the side, which makes lateral tipping more likely to occur due to the offset between the ground contact position of the front caster 16 and the steering shaft 28, the anti-tip-over effect of the auxiliary caster 54 on the ground is effectively exerted against lateral tipping. Note that while FIG. 10 has been described with respect to lateral tipping to the right, it goes without saying that the same anti-tip-over effect is exerted for lateral tipping to the left as well.

In this embodiment, the ground contact portion of the anti-tip device 10 is composed of the auxiliary caster 54, and the ground contact portion is in a pre-contact state not only when a tipping moment that is expected to cause a tipping occurs but also during normal driving conditions. This ensures that the anti-tip effect is quickly achieved when a tipping moment is applied, and also prevents changes in the posture of the wheelchair 12 (such as tilting in the tipping direction).

Figure 11 shows a wheelchair anti-tip device 70 according to a second embodiment of the present invention attached to a wheelchair 12. As shown in Figures 11 to 15, the anti-tip device 70 is attached to the front caster 16 of the wheelchair 12. In the following description, the same reference numerals are used in the figures to designate components and parts that are substantially the same as those in the first embodiment, and descriptions thereof will be omitted.

As shown in Figures 12 to 15, the tip-over prevention device 70 includes a pair of fixing members 72, 72 that are attached to the front caster 16. The fixing member 72 is in the shape of a generally sector-shaped plate with the lower end at the center. A plurality of mounting bolt holes 76 are provided in the upper part of the fixing member 72. The plurality of mounting bolt holes 76 are provided at a predetermined distance from each other in the circumferential direction of the wheel axle 24 (axle insertion hole 74), and in this embodiment, six mounting bolt holes 76, 76, ... are provided. In short, the axle insertion hole 74 is provided in the center part of the sector-shaped fixing member 72, and a plurality of mounting bolt holes 76 are provided in the arc part. The fixing member 72 can also be formed with a lightening hole 40 as necessary to reduce its weight.

The pair of fixing members 72, 72 are arranged to sandwich the fork part 22 of the front caster 16 in the extension direction of the wheel axle 24, and the wheel axle 24 penetrates the lower end in the left-right direction. The pair of fixing members 72, 72 are positioned with respect to the lower end of the fork part 22 by the wheel axle 24. In addition, mounting bolts 78 are inserted into mounting bolt holes 76, 76 arranged in series in a direction parallel to the wheel axle 24 in the pair of fixing members 72, 72, and two mounting bolts 78, 78 inserted between the pair of fixing members 72, 72 are arranged to sandwich the upper part of the fork part 22 on both sides of the wheel travel direction and the opposite direction. As a result, the pair of fixing members 72, 72 are positioned with respect to the upper part of the fork part 22. In this way, the pair of fixing members 72, 72 are positioned at the upper and lower parts with respect to the fork part 22, and the pair of fixing members 72, 72 are fixed to the fork part 22.

Since the pair of fixing members 72, 72 are attached so as to sandwich the fork portion 22, it is easy to accommodate differences in the width dimensions of the fork portion 22 when attaching the pair of fixing members 72, 72, and the device can be attached to multiple types of front casters of different sizes and structures. In addition, the mounting bolt holes 76 through which the mounting bolts 78, 78 are inserted can be appropriately selected, thereby forming an adjustment mechanism that adjusts the mounting position and mounting direction of the tip-over prevention device 70 relative to the fork portion 22. This makes it possible to attach the tip-over prevention device 70 to fork portions 22 of different shapes and sizes, and also allows the orientation and position of the extension member 80 and ground contact portion 96, which will be described later, to be set.

An extension member 80 is attached to each fixed member 72. The extension member 80 is a longitudinal plate or rod extending from the fixed member 72 in the travel direction of the wheel 26, and in this embodiment, is separate from the fixed member 72 and fixed to the fixed member 72 by a plurality of fixing bolts 82. More specifically, the extension member 80 in this embodiment has a base 84 fixed to the fixed member 72 by the fixing bolts 82 that extends downward from the fixed member 72, and a tip 86 that extends from the lower end of the base 84 while inclining downward in the travel direction of the wheel. The extension end 88 of the extension member 80 is disposed close to and above the ground G.

A connecting member 90 is attached to the extension ends 88, 88 of the pair of extension members 80, 80. The connecting member 90 is a plate-like member elongated in the left-right direction. The connecting member 90 is disposed between the extension ends 88, 88 of the pair of extension members 80, 80, and is fixed to each extension member 80 with fixing bolts 94, 94. The connecting member 90 attached to the extension ends 88, 88 of the extension members 80, 80 extends approximately parallel to the ground G with a small inclination relative to the ground G, and is disposed close to and above the ground G.

The extension ends 88, 88 of the extension members 80, 80 and the connecting member 90 constitute the ground contact portion 96 of this embodiment. When the anti-toppling device 70 is attached to the front caster 16, the ground contact portion 96 is disposed at a position offset outward in the wheel travel direction from the ground contact position of the front caster 16 as shown in FIG. 13. When the wheel travel direction is aligned with the front of the wheelchair 12, the ground contact portion 96 is preferably located forward of the rear end of the foot support 20 of the wheelchair 12, and more preferably located directly below or forward of the front-to-rear center of the foot support 20.

When the anti-tip device 70 is attached to the front caster 16, the ground contact portion 96 is disposed above and close to the ground as shown in FIG. 13. It is desirable that the distance h1 of the ground contact portion 96 from the ground G is smaller than the distance H of the wheel axle 24 from the ground G. The distance h1 of the ground contact portion 96 from the ground G is preferably within the range of 1 to 3 cm. This makes it difficult for the ground contact portion 96 to interfere with unevenness on the ground G when the wheelchair 12 is traveling, and can effectively prevent tipping due to ground contact, as described below. For example, a cushioning material may be provided on the underside of the ground contact portion 96 so that the ground contact portion 96 is less likely to damage the floor surface when it touches the ground.

A side member 98 is provided on each fixing member 72. The side member 98 extends outwardly from the side of the wheel 26, inclining downward. The upper part of the side member 98 is overlapped with the fixing member 72, and is fixed to the fixing member 72 by two fixing bolts 100, 100 to form the fixing member 72. The side member 98 is provided with a reinforcing rib 102 that extends continuously in the length direction from the upper part to the lower end.

The lower end of the side member 98 is an auxiliary ground contact portion 104. The auxiliary ground contact portion 104 is provided on each side of the wheel 26. The auxiliary ground contact portion 104 extends approximately parallel to the ground G and is disposed close to and above the ground G. It is desirable that the distance h2 of the auxiliary ground contact portion 104 from the ground G is smaller than the distance H of the wheel axle 24 from the ground G. The distance h2 of the auxiliary ground contact portion 104 from the ground G is preferably within a range of 1 to 2 cm. The distance h2 of the auxiliary ground contact portion 104 from the ground G may be the same as the distance h1 of the ground contact portion 96 from the ground G, or may be different from h1, and in this embodiment, h2>h1.

The side members 98 are attached to each of the pair of fixing members 72, 72, and extend out to one side, so that auxiliary grounding portions 104, 104 are disposed on both sides of the wheel 26. This prevents the wheel 26 from tipping over to either side by one of the auxiliary grounding portions 104 touching the ground G.

The thus constructed anti-tip device 70 is attached to the fork portion 22 of the front caster 16 of the wheelchair 12, so that the orientation of the wheelchair 12 relative to the frame 14 can be changed together with the fork portion 22 by rotating the steering shaft 28. Therefore, the ground contact portion 96 is always positioned in the direction of wheel travel relative to the steering shaft 28, and the auxiliary ground contact portion 104 is always positioned to the side of the wheel 26. In short, even if the orientation of the front caster 16 relative to the frame 14 changes around the steering shaft 28 depending on the direction of movement of the wheelchair 12, the relative positions of the ground contact portion 96 and the auxiliary ground contact portion 104 relative to the wheel 26 are maintained.

By mounting such a tipping prevention device 70 on the front caster 16 of the wheelchair 12, it is possible to prevent the wheelchair 12 from tipping forward and sideways. Note that a forward tipping of the wheelchair 12 occurs when, for example, the user (occupant) of the wheelchair 12 shifts their center of gravity forward by leaning their upper body forward or standing on the foot supports 20. A sideways tipping of the wheelchair 12 occurs when, for example, the user of the wheelchair 12 shifts their center of gravity to the side by leaning their body out to the side.

In a forward movement state of the center of gravity (a downward input state relative to the front of the wheelchair 12) in which forward tipping of the wheelchair 12 becomes an issue, the wheel travel direction is in front of the wheelchair 12, and the ground contact position of the wheels 26, which are offset to the opposite side of the wheel travel direction relative to the steering axis 28, is further rearward. Since the ground contact position of the wheels 26 is the central axis of the moment that causes forward tipping (tipping moment axis), the distance from the point of application of the downward load on the front of the wheelchair 12 to the tipping moment axis becomes longer, and a large moment acts about the tipping moment axis, making it easy for the wheelchair 12 to tip forward.

When the anti-tip device 70 is attached to the wheelchair 12, when a forward tipping moment acts, the ground contact portion 96 of the anti-tip device 70, which is located forward of the steering axis 28, touches the ground G, and the tipping moment axis shifts from the ground contact position of the wheels 26 to the ground contact position of the ground contact portion 96, and the tipping moment axis is set further forward. Therefore, the distance from the downward input to the front of the wheelchair 12 to the tipping moment axis is shortened, and the moment around the tipping moment axis from the point of application of the downward load to the front of the wheelchair 12 is reduced, making it less likely for the wheelchair 12 to tip forward.

In a state where the center of gravity is shifting to the side, causing the wheelchair 12 to tip over to the side, the wheels 26 of the front casters 16 rotate around the steering shaft 28, and the wheel travel direction is to the side of the wheelchair 12. The ground contact position of the wheels 26 is set further inward in the left-right direction due to the offset between the wheel shaft 24 and the steering shaft 28. In a traveling state where the ground contact portion 96 is away from the ground, the tipping moment axis in a side tipping is a straight line connecting the ground contact position of the rear wheels 18 of the wheelchair 12 and the ground contact position of the wheels 26 of the front casters 16. Therefore, when the wheel travel direction is the left-right direction of the wheelchair 12 and the ground contact position of the wheels 26 is set to the inside left-right, the distance from the point of application of the downward load applied to the side of the wheelchair 12 by the user's center of gravity shift to the tipping moment axis becomes longer, making side tipping more likely to occur.

The anti-tip device 70 rotates around the steering shaft 28 together with the front caster 16, so in a state where lateral tipping is a problem when the wheel travel direction is the left-right direction of the wheelchair 12, the ground contact part 96 is located outward (to the outside of the side of the user's center of gravity movement) in the left-right direction of the wheelchair 12 relative to the wheels 26. When the wheelchair 12 tries to tilt to the side due to the tipping moment, the ground contact part 96 of the anti-tip device 70 touches the ground G, and the tipping moment axis shifts to a straight line connecting the ground contact position of the rear wheel 18 of the wheelchair 12 and the ground contact part 96, and the tipping moment axis is set further outward to the left and right. This shortens the distance from the downward input position on the side of the wheelchair 12 to the tipping moment axis, reducing the moment around the tipping moment axis due to the input to the side of the wheelchair 12, making it less likely for the wheelchair 12 to tip sideways.

As described above, in the front caster 16 in which the steering axle 28 and the ground contact position of the wheel 26 are offset, the tipping moment axis is located on the opposite side to the wheel travel direction, making tipping in the wheel travel direction more likely to be a problem. The tipping prevention device 70 of this embodiment is attached to the fork section 22 that rotates around the steering axle 28 together with the wheel 26, so that the ground contact part 96 is always located in the wheel travel direction relative to the wheel 26, and the contact of the ground contact part 96 can shift the tipping moment axis closer to the input position that causes the tipping. Therefore, according to the tipping prevention device 70, the contact of the ground contact part 96 can provide an effective tipping prevention effect regardless of whether the tipping direction is forward or to the side.

If the wheel 26 gets caught on an uneven surface of the ground G, causing the wheel 26 to tip over without the wheel moving in the same direction as the input direction, causing a forward or lateral tipping to occur, the auxiliary grounding portion 104, which is located laterally outboard of the grounding position of the wheel 26, will touch the ground, shifting the tipping moment axis further outboard, thereby preventing the wheelchair 12 from tipping over to the side with the wheel 26 tipping over.

The ground contact portion 96 and the auxiliary ground contact portion 104 are both located above the ground G, so they are unlikely to affect the normal running of the wheelchair 12. In addition, because the ground contact portion 96 and the auxiliary ground contact portion 104 are both located close to the ground G, they quickly come into contact with the ground when there is an input that may cause a fall, providing a fall prevention effect. In particular, in this embodiment, the distance h1 of the ground contact portion 96 from the ground G is within a range of 1 to 3 cm, so that the fall prevention effect can be effectively obtained while preventing adverse effects on running. Similarly, the distance h2 of the auxiliary ground contact portion 104 from the ground G is within a range of 1 to 2 cm, so that the fall prevention effect can be effectively obtained while preventing adverse effects on running.

In this embodiment, a plurality of mounting bolt holes 76 are formed in each of the fixing members 72, 72, and the distance of the ground contact portion 96 from the ground G (the timing of contact with the ground G) can be adjusted by appropriately selecting the mounting bolt holes 76 through which the mounting bolts 78, 78 are inserted. In addition, by setting the distance h1 of the ground contact portion 96 from the ground G to be large, interference with the ground contact portion 96 due to the inclination or unevenness of the ground G when the wheelchair 12 is moving can be easily avoided, and the influence on the movement can be further suppressed. On the other hand, by setting the distance h1 of the ground contact portion 96 from the ground G to be small, the tipping motion of the wheelchair 12 can be stopped at an earlier stage by the touchdown of the ground contact portion 96, and the tipping prevention performance can be improved.

Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the specific description. For example, in the above embodiment, the prevention of forward and lateral tipping has been described as an example of preventing the wheelchair 12 from tipping over. However, for example, a diagonal forward tipping, such as a combination of forward and lateral tipping, can also be prevented by keeping the ground contact position of the auxiliary caster 54 following the front caster 16 in the direction of travel of the front caster 16. In short, the tipping prevention device 10 can effectively prevent tipping caused by a shift in the user's center of gravity, etc., in a range of approximately 180 degrees from both sides to the front of the wheelchair 12.

The method of fixing the fall prevention device 10 to the fork portion 22 is not particularly limited, and it is not necessary to fix it by sandwiching it between a pair of fixing members. For example, it is possible to omit the pair of fixing members by fixing the connecting member 42 of the second embodiment directly to the fork portion 22 with screws or the like.

The fixing member of the tip-over prevention device 10 can be provided integrally with the fork portion 22. It is preferable that the tip-over prevention device 10 is retrofitted separately from the front caster 16 so that it can be applied to an existing wheelchair 12, but it may also be provided integrally with the front caster 16 of the wheelchair 12 in advance, for example.

10 Fall prevention device (first embodiment)
REFERENCE SIGNS LIST 12 wheelchair 14 frame 16 front wheel caster 18 rear wheel 20 foot support 22 fork portion 24 wheel axle 26 wheel 28 steering axle 30 fixing member 32 axle insertion hole 34 connecting bolt hole 36 mounting bolt hole 38 reinforcing plate 40 lightening hole 42 connecting member 44 cavity 46 connecting bolt hole 47 connecting bolt 48 adjuster (adjusting mechanism)
50 Adjustment screw 52 Contact member 54 Auxiliary caster (ground contact portion)
56 Steering shaft 58 Wheel shaft 60 Mounting bolt 70 Anti-toppling device (second embodiment)
72 Fixing member 76 Mounting bolt hole (adjustment mechanism)
78 Mounting bolt (adjustment mechanism)
80 Extension member 82 Fixing bolt 84 Base portion 86 Tip portion 88 Extension end portion 90 Connection member 94 Fixing bolt 96 Ground contact portion 98 Side member 100 Fixing bolt 102 Reinforcing rib 104 Auxiliary ground contact portion G Ground surface

Claims (7)

A wheelchair tip-over prevention device that is attached to a wheelchair equipped with front wheel casters in which a steering axis is offset in a wheel travel direction from a wheel axis, comprising:
The steering shaft is rotatable about a ground contact portion supported by a fork portion of the front caster.
The ground contact portion contacts the ground outside the ground contact position of the front wheel caster in the direction of travel of the wheel, thereby preventing the wheelchair from tipping over. The anti-tip device according to claim 1, wherein the ground contact portion is constituted by an auxiliary caster that contacts the ground at a position offset in the wheel travel direction from the front caster when the wheelchair is in a traveling state. The anti-tip device according to claim 1, wherein the ground contact portion is disposed close to and above the ground at a position offset in the wheel travel direction from the front caster when the wheelchair is in a traveling state. An anti-tip device according to any one of claims 1 to 3, in which a pair of fixing members are provided that sandwich the fork portion of the front caster from both sides in the extension direction of the wheel axle and are fixed to the fork portion, and the ground contact portion is supported by the fork portion via the pair of fixing members. An anti-tipover device according to claim 4, in which a pair of extension members extending forward in the wheel travel direction from the pair of fixed members are fixed to the pair of fixed members, and the ground contact portion is provided at the extended end of the pair of extension members. An anti-tip device as described in claim 4, which is provided with an adjustment mechanism for adjusting the mounting position of the fixing member relative to the front caster. An auxiliary grounding portion is provided on the side of the front caster,
The anti-tip device according to any one of claims 1 to 3, wherein the front caster is prevented from tipping sideways by the auxiliary grounding portion contacting the ground.

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