JP2011156044A - Front wheel caster for wheelchair and wheelchair - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a caster for a wheelchair front wheel, of which straight running stability and level difference overriding capability are improved. <P>SOLUTION: The wheelchair includes the front wheel caster including: a caster wheel rotated centering around a predetermined rotary shaft; an auxiliary wheel arm rotated centering around the rotary shaft and provided with a rotary shaft at the end part; an auxiliary wheel rotated centering around the rotary shaft and having a diameter smaller than that of the caster wheel; and a spring member for urging the auxiliary wheel to a ground surface. The eccentric amount of the caster wheel is reduced, and the diameter of the caster wheel is increased. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a wheelchair front wheel caster and a wheelchair.

There are two main problems in the outdoor running of wheelchairs that use a free caster on the front wheels for steering.
One is meandering and poor straightness. Secondly, it is difficult to get over even a small level difference.
FIGS. 13, 14, 15-a, 15-b, 16-a, 16-b, 16-c, 16-d, 17-a, 17-b, FIG. 17-c, 17-d, 17-e, 17-f, 18-a, 18-b, 18-c, 18-d, 19-a and 19-b To do.

FIG. 13 is a mounting diagram of the front wheel caster 120 of the wheelchair 30 of the prior art. In the front wheel caster 120, a caster shaft 130 is fixed to a frame 30a that is lowered from a side armrest of the wheelchair 30 in FIG. The caster wheel 140 can freely turn on a horizontal plane around the caster shaft 130.

FIG. 14 is an enlarged view of a portion E in FIG. 13, and is a structural diagram of the front wheel caster 120.
The caster wheel 140 having the diameter D2 is eccentric with the caster shaft 130 and the horizontal distance L4. The rubber or resin tire caster wheel 140 can freely turn in a horizontal plane around the caster shaft 130.

The caster wheel diameter D2 of the self-propelled and nursing wheelchairs is 130 mm (5 in) to 180 mm (7 in). The ratio of the eccentric L4 of the caster wheel to the caster wheel diameter D2 and the eccentricity E2 are approximately 0.3.
The eccentricity E2 between the caster wheel diameters 100 and 200 of the caster manufacturer A is 0.27 to 0.33, and the eccentricity E between the caster wheel diameters 100 and 200 of the caster manufacturer B is 0.28 to It was 0.35.

[About bad straightness]

As shown in FIG. 14, since there is a horizontal distance L4 due to eccentricity between the caster shaft 130 and the ground contact point P3 of the caster wheel 140, when the caster shaft 130 is moved by the movement of the wheelchair, the caster wheel 140 is Swing the head according to the traveling direction of the caster shaft 130 to follow.

18A shows a straight traveling state of the rear wheels 40l and 40r and the caster wheels 140l and 140r, and FIG. 18B shows a turning state of the rear wheels 40l and 40r and the caster wheels 140l and 140r. If the four wheels of the rear wheels 40l and 40r and the caster wheels 140l and 140r can touch the running surface at the same time, the wheelchair can travel straight and turn without meandering as shown in FIGS. 18A and 18B. .

However, when traveling on a general sidewalk, the wheelchair 140 swings in a direction different from the traveling direction due to repeated unevenness of the road surface and small changes in slope, and the wheelchair moves in the traveling direction only by applying a forward force to the wheelchair. Then it will meander.

There are two main causes of meandering because of poor straightness.

One reason is that a state occurs in which the caster wheels can freely turn regardless of the traveling direction.

This will be described with reference to FIGS. 15-a and 15-b.
The caster wheels 140l, 140r swing in the direction different from the traveling direction is a structure in which the left and right front wheel casters 120l, 120r can turn independently and freely, and the rear wheels 40l, 40r and the front wheel casters 120l, When the mounting height of 120r is fixed and only one wheel of the caster wheel 140r is floated as shown in FIGS. 15A and 15B, or when the running surface is concave, the caster wheel 140r is This is because the vehicle can turn freely regardless of the traveling direction. When the caster wheel 140r is inclined to the grounded slope again, the caster wheel 140r swings its head in accordance with the tilt and begins to meander.

Second, the caster wheel follows the inclination of the cross section perpendicular to the traveling direction.

It also meanders when the cross section perpendicular to the direction of travel is not horizontal but inclined to one side.
FIG. 16A and FIG. 16B will be described. In FIG. 16-b, the caster wheel 140 of the front wheel caster 120 is traveling on an uphill with an inclination descending to the front side of the drawing.
The caster shaft 130 receives the weight of the wheelchair 30, and is centered on the ground contact point P3 of the caster wheel 140, which is generated by following the inclination of the right-angled cross section in the traveling direction (uphill) (down to the front of the page in FIG. 16B). As a result, the caster wheel 140 is steered in the clockwise direction by the force M3a which is generated at the position of the radius L4 and tries to rotate the caster shaft, and the meandering starts.
In order to prevent meandering, in the case of a self-propelled wheelchair, a force M4a for steering in the opposite direction to meandering is given to the handling of the rear wheel 40 driven by human power, and the forces of M3a and M4a are offset. In the wheelchair for the caregiver, a clockwise force is transmitted to the pusher 150 in FIG. 13, so that the pusher is reversely rotated to prevent meandering.

16-c and 16-d will be described. In FIG. 16-d, the caster wheel 140 of the front wheel caster 120 is traveling on a downhill having an inclination descending to the front side of the drawing.
The caster shaft 130 receives the weight of the wheelchair 30, and is centered on the ground contact point P3 of the caster wheel 140, which is generated following the inclination of the right-angled cross section in the traveling direction (downhill) (down to the front of the paper in FIG. 16-d). As a result, the caster wheel 140 is steered in the clockwise direction by the force M3c to rotate the caster shaft generated at the position of the radius L4, and the meandering starts.
In order to prevent meandering, in the case of a self-propelled wheelchair, a force M4a for steering in the opposite direction to meandering is given to the handling of the rear wheel 40 driven by human power, and the forces of M3a and M4a are offset. In the wheelchair for the caregiver, a clockwise force is transmitted to the pusher 150 in FIG. 13, so that the pusher is reversely rotated to prevent meandering.

[It is difficult to get over even with a small step]
There are two main causes.

For one thing, the wheel diameter is smaller than the steps that are close.

FIG. 17B is a diagram in which the caster wheel is slightly lifted as the wheelchair advances so that the front wheel caster 120 having a diameter D2 of 180 mm of the caster wheel 140 gets over the step 23 mm.
At this time, the angle K7 at which the caster wheel 140 comes into contact with the step becomes 42 degrees, and a force to climb up the slope corresponding to the ascending slope 8.9 / 10 is temporarily required. In the self-propelled type, if the wheelchair is gained momentum, it is a height that cannot be overcome, but the wheelchair's center of gravity is much higher than the step, so there is a risk that the passenger will be thrown out. A wheelchair for a caregiver is dangerous unless the front wheel caster 120 is lifted and climbed over.

17B, FIG. 17C, and FIG. 17D will be described. FIG. 17B is a diagram of the caster wheel 140 with a diameter D2 of 180 mm, and the front wheel caster 120 starts overcoming the step 23 mm, FIG. 17C is a diagram in the middle of overcoming, and FIG. 17D is a diagram near the end of the overriding. is there. What can be said about FIGS. 17-b, 17-c, and 17-d is that K7> K8> K9, the angle at which the caster wheel 140 first contacts the step is the maximum, and the caster wheel 140 gets over the step. Depending on the degree, the angle at which the caster wheel 140 contacts the step decreases, and when the step over the step is over, it becomes 0 degree. In other words, overcoming a step means that there is maximum resistance at the beginning of overcoming, and at this time, maximum force is required.

FIG. 17-e shows a step of 46 mm, which cannot be overcome. The angle K10 at which the caster wheel 140 having a wheel diameter D2 of 180 mm contacts is 61 degrees, which corresponds to an upward gradient of 1.8 / 10.
FIG. 17-f shows a step of 11.5 mm, which is easy to get over. An angle K11 at which the caster wheel 140 having a wheel diameter D2 of 180 mm contacts is 31 degrees, which corresponds to an ascending slope of 6/10.

The second reason is that the caster wheel 140 may swing its head in accordance with the surface or corner of the step at the moment of hitting the step.

As shown in FIG. 14, the caster wheel 140 has the eccentricity of the caster shaft 130 and L4. The eccentric L4 allows the caster wheel 130 to follow the caster shaft in the direction of travel, but it cannot be more than a certain level difference.

In FIG. 17-a, when there is a step T that is in contact with the caster wheel 140 at the contact point P4 immediately below the axis of the caster shaft 130, the caster wheel 140 collides with the step and tries to get over it. When the center of gravity of the wheel 140 is about to move to a step, the contact point P3 with the traveling surface of the caster wheel 140 disappears.
The contact point of the caster wheel 140 is only P4, the horizontal distance between the caster shaft 120 and the contact point P4 is zero, and the ability of the caster wheel 140 to follow in the traveling direction is zero.
Incidentally, when the wheel diameter D2 of the caster wheel 140 is 180 mm, the step contacted at the contact point P4 is about 23 mm.

18-c and 18-d show the straight traveling state of the rear wheels 40l and 40r and the caster wheels 140l and 140r.
The upper half of FIG. 18-c is a view in which the caster wheel 140l tries to collide with the obstacle l of the step T having an angle K12 in the traveling direction while maintaining the ability to follow the traveling direction of the wheelchair. is there. The lower half of FIG. 18-c loses the ability of the caster wheel 140r to follow the direction of travel of the wheelchair (occurs when the caster wheel 140r moves away from the running surface) and proceeds with the head swung. It is a figure which is going to collide with the obstacle r of the level | step difference T perpendicular to a direction.

FIG. 18D is a view in which the above-mentioned caster wheels 140l and 140r collide with the obstacle l and the obstacle r, respectively, and the front wheel caster 120 swings its head due to the bending force and cannot move forward.

FIG. 19A and FIG. 19B are views of a front wheel caster fitted in a rainwater drainage groove in an apartment corridor. The front wheel caster 120 turns freely when only the caster wheel 140 on one side is floating above the groove, and easily fits into a shallow narrow groove. Since the groove cannot move with momentum, it is difficult to pass if the groove width is more than 1/2 the caster wheel diameter even if it is shallow.
The size of the groove shown in the drawing is a width L3 of about 120 mm and a depth H1 of about 30 mm. When the wheel diameter D2 of the caster wheel 120 is 180 mm, the contact angle K13 between the caster wheel 120 and the corner of the groove is 41 degrees, which corresponds to an ascending slope of 9/10, which is a groove size that cannot be exceeded.

It is an object of the present invention to provide a wheelchair equipped with a front wheel caster with improved straightness and ability to ride over a step.

A caster wheel that rotates about a predetermined rotation axis, an auxiliary wheel arm that rotates about the rotation axis, and the auxiliary wheel arm further has a rotation shaft at an end, and the rotation axis is the center. The auxiliary wheel having a smaller diameter than the caster wheel that rotates in turn, and a spring member for biasing the auxiliary wheel to the running surface, the eccentric amount of the caster wheel is reduced, and the diameter of the caster wheel is reduced. A wheelchair equipped with a front wheel caster, which is characterized by being enlarged.

The front wheel caster 50 according to the present invention urges the auxiliary wheel 90 toward the traveling surface by the spring members 1 and 2, and therefore prevents the self-turning when the caster wheel 70 is separated from the traveling surface. Since the swing of the influence due to the change in the inclination of the surface can be reduced, the straight running performance can be particularly improved. Since the eccentric L1 of the caster wheel 70 is reduced and the turning diameter of the caster wheel is reduced, the wheel diameter can be increased, so that the wheel diameter can be increased by 300 mm and the step overcoming ability is improved. In addition, since the wheel diameter has been increased, it is possible to equip with pneumatic tires and further improve the ability to climb over steps.

FIG. 1 is an overall configuration diagram of a wheelchair front wheel caster and a wheelchair according to a first embodiment of the present invention. Fig. 1 is an excerpt of the wheel section seen from the arrow A (the state of the rear wheel and front wheel caster when the wheelchair goes straight) Fig. 1 A wheel section excerpt (state of the rear wheel and front wheel caster when turning the wheelchair) Part B enlarged view of FIG. Wheelchair front wheel caster equipped with the pneumatic tire of Example 2 of the present invention Front wheel caster rugged surface (with one wheel lifted up) Front wheel caster uneven surface (state where one wheel is recessed) Front wheel caster uphill view (plane) Front wheel caster uphill (side view) Front wheel caster downhill view (plane) Front wheel caster downhill (side view) Front wheel casters and steps (1) Front wheel caster and step (2) Front wheel caster and step (3) Front wheel casters and steps (4) Front wheel casters and steps (5) Front wheel casters and steps (6) Front wheel casters equipped with pneumatic tires and steps (1) Front wheel casters equipped with pneumatic tires and steps (2) Front wheel casters equipped with pneumatic tires and steps (3) Front wheel casters equipped with pneumatic tires and steps (4) Front wheel caster groove (1) Front wheel caster groove (2) Front wheel caster groove (3) C arrow enlarged view of FIG. D arrow enlarged view of FIG. 3 is an enlarged cross-sectional view of the main part viewed from the arrow C in FIG. Front wheel caster installation state diagram of the wheelchair of the prior art E part enlarged view of FIG. Illustration of running on the uneven surface of a front wheel caster (with one wheel lifted up) Illustration of running on the uneven surface of the front wheel caster (state where the running surface of one wheel is recessed) Front wheel caster and uphill view (plane) Front wheel caster and uphill view (side view) Front wheel caster and downhill diagram (plane) Front wheel caster and downhill diagram (side view) Front wheel casters and steps (1) Front wheel caster and step (2) Front wheel caster and step (3) Front wheel casters and steps (4) Front wheel casters and steps (5) Front wheel casters and steps (6) 13 is an excerpt of the wheel section seen from the arrow F in FIG. 13 (the state of the rear wheel and front wheel caster when the wheelchair goes straight). Figure F excerpt wheel part view of Fig. 13 (Rear wheel and front wheel caster during wheelchair turning) Fig. 13 F excerpt wheel part view (when the wheelchair goes straight, the position of the front wheel casters and obstacles) Fig. 13 F excerpt wheel section (when the front wheel caster hits an obstacle and swings his head when the wheelchair goes straight) Front wheel caster and groove (1) Front wheel caster and groove (2)

Embodiment 1 and Embodiment 2 of the present invention will be described in detail with reference to the drawings.

The first embodiment of the present invention is shown in FIGS. 1, 2-a, 2-b, 3, 5-a, 5-b, 6-a, 6-b, 6-c, 6 -D, Figure 7-a, Figure 7-b, Figure 7-c, Figure 7-d, Figure 7-e, Figure 7-f, Figure 9-a, Figure 9-b, Figure 9-c, Figure 10 11 and 12 will be described.

FIG. 1 is an overall configuration diagram of Embodiment 1 of the present invention, in which a wheelchair having a general function and performance is equipped with a wheelchair front wheel caster 50 of Embodiment 1 of the present invention.
In the front wheel caster 50, a caster shaft 60 is fixed to a frame 30a that descends from a side armrest of the wheelchair 30 of FIG. The caster wheel 70 and the auxiliary wheel 90 can freely turn on a horizontal plane around the caster shaft 60.

FIG. 2A is a diagram showing the straight traveling state of the rear wheels 40l and 40r, the caster wheels 70l and 70r and the auxiliary wheels 90l and 90r when the wheelchair is going straight, and FIG. 2-b is the rear wheels 40l and 40r and the caster wheel when the wheelchair is turning. It is a state diagram of turning of 70l, 70r and auxiliary wheels 90l, 90r. FIG. 3 is an enlarged view of part B of FIG. 1 and is an overall view of the wheelchair front wheel caster 50 according to the first embodiment of the present invention.

FIG. 10 is an enlarged view taken along arrow C in FIG. 3, and FIG. 11 is an enlarged view taken along arrow D in FIG. FIG. 12 is a cross-sectional view of the caster wheel rotating shaft portion and the auxiliary wheel rotating shaft portion.
[Description of Configuration of Example 1]

The front wheel caster 50 is located on the caster shaft 60 fixed to the frame 30a descending from the side armrest of the wheelchair 30 in FIG. 1, and at the end of the fork portion 60a of the caster shaft 60 as shown in FIG. A caster wheel 70 of rubber or resin tire that rotates about the rotation shaft 70 a, an auxiliary wheel arm 80 that can freely rotate about the rotation shaft 70 a, and a rotation shaft at the end of the auxiliary wheel arm 80 90a, an auxiliary wheel 90 that rotates about the rotating shaft 90a and has a smaller diameter than the caster wheel 70, spring members 1 and 2 for urging the auxiliary wheel 90 against the running surface, and the caster shaft The fork portion 60a side spring member hook pins 3 and 4 and the stoppers 5 and 6 for limiting the movement range of the auxiliary wheel arm 80 are configured. As shown in FIG. 3, the auxiliary wheel 90 is at an eccentric position L2 at a horizontal distance from the rotating shaft 70a of the caster wheel 70.

[Functions of the first embodiment will be described]
FIG. 2A shows a straight traveling state of the rear wheel 40 and the front wheel caster 50, and FIG. 2-B shows a turning state of the rear wheel 40 and the front wheel caster 50. Although the improvement of the function will be described later in comparison with the prior art, the wheelchair equipped with the front wheel caster 50 has improved turning performance as well as the improvement of the straight direction performance described above.

With reference to FIG. The front wheel caster 50 shown in the drawing has an eccentricity of the horizontal distance L1 from the rotation center of the caster shaft 60 and the caster wheel 70. In the present invention, the turning range of the caster wheel is reduced, and the diameter of the caster wheel is increased accordingly. The ratio of the eccentricity L1 to the caster wheel diameter D1 and the eccentricity E1 were 0.15 or less (including eccentricity 0). For this reason, the caster wheel diameter D1 could be more than 300 mm.

The auxiliary wheel 90 that rotates about the rotating shaft 90a at the end of the auxiliary wheel arm 80 that is freely attached to the rotating shaft 70a of the caster wheel 70 is always biased to the traveling surface by the spring members 1 and 2. Therefore, even if the caster wheel 70 is separated from the traveling surface, the caster wheel 70 can follow the traveling direction of the wheelchair.

Comparison with the prior art will be described with reference to the drawings.

[Improvement of straightness]

For one thing, the caster wheel 70 is prevented from turning in a direction different from the traveling direction.

As shown in FIG. 3, the front wheel caster 50 prevents the self-turning when the caster wheel 70 is lifted from the traveling surface because the auxiliary wheel 90 is always in contact with the traveling surface under the spring pressure. be able to.

FIGS. 5A and 5B are views showing the state of the caster wheels 70l and 70r and the auxiliary wheels 90l and 90r traveling on the uneven surface.
In FIG. 5A, since the left caster wheel 70l has climbed on the convex portion, the right caster wheel 70r has moved away from the traveling surface. However, since the auxiliary wheel 90r is in contact with the traveling surface, the caster wheel 70r maintains the traveling direction and does not turn freely.

In FIG. 5B, the left caster wheel 70l is on a flat traveling surface, but the traveling surfaces of the right caster wheel 70r and the auxiliary wheel 90r are recessed, and the right caster wheel 70r is separated from the recessed surface. . However, since the auxiliary wheel 90r is in contact with the concave surface, the caster wheel 70r maintains the traveling direction and does not turn freely.

Second, it generates a force that counteracts the force following the inclination of the cross section perpendicular to the traveling direction of the caster wheel to prevent meandering.

This will be described with reference to FIGS. In FIG. 6B, the caster wheel 70 of the front wheel caster 50 is traveling uphill with an inclination that descends to the front side of the drawing.
The weight of the wheelchair 30 is received by the caster shaft 60 and centered on the ground contact point P1 of the caster wheel 70, which is generated following the inclination of the cross section perpendicular to the traveling direction (uphill) (down to the front of the paper in FIG. 6B). As a result, a force M1a which is generated at the position of the radius L1 and tries to turn the caster shaft is received. However, the auxiliary wheel 90 pressurized with a spring on the running surface at a distance of L2 from the caster shaft opposes the force of M1a trying to rotate the caster shaft in the clockwise direction. M2a is generated at a position P2 having a radius L2-L1 to prevent counterclockwise rotation about the contact point P1 of the surface, thereby canceling each other and preventing meandering. Since L1 is 15% or less of the caster wheel diameter and L2-L1 is about 60% of the caster wheel diameter, M2a may generate a force of 1/4 of M1a at the maximum.

This will be described with reference to FIGS. 6C and 6D. In FIG. 6-d, the caster wheel 70 of the front wheel caster 50 is traveling on a downhill having an inclination that descends to the front side of the drawing.
The weight of the wheelchair 30 is received by the caster shaft 60 and centered on the ground contact point P1 of the caster wheel 70, which is generated by following the inclination of the right-angled cross section in the traveling direction (downhill) (down to the front of the page in FIG. 6C). As a result, a force M1c which is generated at the position of the radius L1 and tries to turn the caster shaft is received. However, the auxiliary wheel 90 pressurized with a spring on the running surface at a distance of L2 from the caster shaft opposes the force of M1c trying to turn the caster shaft clockwise, and the caster wheel travels. M2c is generated at a position P2 having a radius L2-L1 to prevent counterclockwise rotation about the contact point P1 of the surface, thereby canceling each other's force and preventing meandering. Since L1 is 15% or less of the caster wheel diameter and L2-L1 is about 60% of the caster wheel diameter, M2c may generate a force that is 1/4 of M1c at the maximum.

[About the ability to climb over steps]

For one thing, the wheel diameter was increased.

As shown in FIG. 3, the ratio E1 of the caster shaft 60 and the eccentric L1 of the caster wheel to the diameter D1 of the caster wheel 70 is reduced to 0.15 or less, and the turning range of the caster wheel about the caster shaft is reduced. Since the caster wheel diameter D1 can be increased, the diameter of the caster wheel 70 can be increased to more than 300 mm.

FIGS. 7A and 7B are diagrams showing how a conventional caster wheel gets over a step of 23 mm with danger.
FIG. 7A is a view in which a caster wheel 70 having a diameter of 300 mm contacts the step. The contact angle K1 at this time is 32 degrees, and the upward gradient is 6.3 / 10.
This contact angle and ascending slope are approximately the same level as the ascending slope 6/10, 31 degrees of the angle K7 at which the caster wheel of the conventional 180 mm contact with the 11.5 mm step shown in FIG. Can be said to be easier.

FIG. 7E is a view of getting over a step of 46 mm.
FIG. 7E is a view in which a caster wheel 70 having a diameter of 300 mm contacts the step. The contact angle K3 at this time is 46 degrees, and the ascending slope is 10.4 / 10.
The contact angle and the ascending slope are as shown in FIG. 17-b, where the conventional 180 mm caster wheel contacts the 23 mm step, which is an angle K7 of 42 degrees, and the ascending slope is 9/10. I can say that.

FIG. 7-f is a diagram of overcoming the step of 11.5 mm.
FIG. 7F is a view in which a caster wheel 70 having a diameter of 300 mm contacts the step. At this time, the contact angle K4 is 22.6 degrees, and the ascending slope is 4.2 / 10. Overcoming without problems.

Secondly, the caster wheels have the ability to maintain the direction of travel even when the caster wheels get over the step.

7-b, 7-c and 7-d show each step of stepping over the step. In the front wheel caster 120 of the prior art, the ability to follow the caster wheel 130 in the traveling direction is lost when a certain level difference is exceeded, but in the front wheel caster 50 shown in FIGS. 7-b, 7-c and 7-d, Since the auxiliary wheel 90 is always in contact with the running surface from when the caster wheel 70 comes into contact with the step, the front wheel caster has the ability to follow the traveling direction while the caster wheel gets over the step. Is maintained.

In the prior art shown in FIGS. 19A and 19B, when the front wheel caster 120 floats on the groove and only the caster wheel 140 on one side, it turns freely and easily fits in a shallow narrow groove. Since the groove cannot be moved with momentum, it was difficult to pass if it was shallow but had a groove width that was 1/2 or more of the caster wheel diameter.
FIG. 9A, FIG. 9B, and FIG. 9C are diagrams of each stage in which the caster wheels get over the rainwater drainage in the corridor outer corridor.
In FIG. 9A, the caster wheel 70 is on the corner in front of the rainwater drain. In FIG. 9B, the caster wheels 70 having a diameter of 300 mm are on the corners on both sides of the rainwater drainage groove. At this time, the contact angle between the rear corner and the caster wheel 70 having a diameter of 300 mm is 23.5 degrees, and the upward gradient is 4.4 / 10. This can be easily overcome because it is sufficiently smaller than 6.3 / 10 ascending gradient when overcoming the step of 23 mm in FIG. In FIG. 9C, the caster wheel 70 finishes over the rainwater drainage groove, and the auxiliary wheel 90 remains in the rainwater drainage groove. If the caster wheel 70 further moves forward, the auxiliary wheel 90 is lifted from the rainwater drain without any problem. The caster wheel 70 not only can easily get over the rainwater drainage groove as described above, but also has an ability to always follow the traveling direction of the wheelchair 30 because the auxiliary wheel 90 is always in contact with the ground.

[Description of Configuration of Example 2]

This will be described with reference to FIG. The second embodiment differs from the first embodiment only in that the caster wheels 110 of the front wheel casters 100 of the second embodiment are equipped with pneumatic tires.
[Functions of Example 2 will be described]

The function of the second embodiment is completely the same as that of the first embodiment.

[About the ability to climb over steps]

The front wheel caster 100 according to the second embodiment will be described because the ability to climb over a step is improved as compared with the first embodiment.

This will be described with reference to FIGS. 8-a, 8-b, 8-c, and 8-d. FIG. 8A is a diagram in which the caster wheel 110 contacts with a step of 23 mm. This is no different from Example 1. FIG. 8B is a diagram in which a step has been started. The caster wheel moves forward, and while the caster wheel is grounded, the corner of the step gradually bites into the pneumatic tire of the caster wheel. FIG. 8C is a diagram in which the caster wheel 110 is lifted from the running surface after the entire weight of the caster wheel 110 is placed on the step. FIG. 8D shows a state in which the caster wheel 110 has climbed up. Although the auxiliary wheel is not on the step, if the caster wheel 110 is further advanced, the auxiliary wheel is easily on the step. If the caster wheel 110 goes down the step and further advances, the auxiliary wheel can also go down to the flat ground without difficulty.
As described in the description of the prior art, the caster wheel using the rubber or resin tire of Example 1 requires the maximum force at the beginning of the step, whereas the caster wheel using the pneumatic tire has the step of the pneumatic tire. It dents at the corner and distributes the resistance from the first small resistance to climbing up the step, so you can get over with a small force by overcoming the step.

DESCRIPTION OF SYMBOLS 1 Spring member 2 Spring member 3 Spring member hook pin 4 Spring member hook pin 5 Stopper pin 6 Stopper pin 30 Wheelchair 40 Rear wheel 50 Front wheel caster 60 Caster shaft 70 Caster wheel 80 Auxiliary wheel arm 90 Auxiliary wheel 100 Front wheel caster 110 caster wheel 120 front caster 130 caster shaft 140 caster wheel 150 pusher D1 caster wheel diameter D2 caster wheel diameter E1 ratio of caster wheel eccentricity L1 to caster wheel diameter D1 ratio E2 ratio of caster wheel L4 to caster wheel diameter D2 H1 Depth of rainwater drainage in the corridor outside the apartment K1 Contact angle between caster wheel and step K2 Contact angle between caster wheel and step K3 Contact angle between caster wheel and step K4 Contact between caster wheel and step Corner K5 Contact angle between the caster wheel and the rear corner of the rainwater drainage in the apartment corridor K6 Contact angle between the caster wheel and the step K7 Contact angle between the caster wheel and the step K8 Contact angle between the caster wheel and the step K9 Castor wheel Contact angle K10 between the caster wheel and the step K11 Contact angle K12 between the caster wheel and the step K12 Angle of the obstacle with an inclination in the traveling direction K13 Contact angle L1 Eccentric amount of caster wheel L2 Eccentric amount of auxiliary wheel L3 Width of condominium corridor rainwater drainage groove L4 Eccentric amount of caster wheel M1a The weight of the wheelchair is received by the caster shaft, and the traveling direction (uphill) The ground contact point with the traveling surface of the caster wheel, which occurs when following the inclination of the right-angled section (down to the front of the page in FIG. 6B), is The force M2a that tries to turn the caster shaft generated at the position of the radius L1 as the auxiliary wheel pressed against the running surface against the force M1a that tries to turn the caster shaft A force M1c that is not to be rotated generated at a position of radius L2-L1 centered on the ground contact point. The wheelchair shaft receives the weight of the wheelchair, and the inclination of the perpendicular section in the traveling direction (downhill) (paper surface of FIG. 6-d). The force M2c that attempts to rotate the caster shaft and that occurs at the position of the radius L1 centering on the ground contact point with the traveling surface of the caster wheel. The force M1c that attempts to rotate the caster shaft Against this, the auxiliary wheel pressurized on the running surface is generated at the position of radius L2-L1 centering on the ground contact point with the running surface of the caster wheel. When the star axis is received, the radius L4 is centered on the ground contact point with the traveling surface of the caster wheel, which is generated following the inclination of the cross section perpendicular to the traveling direction (uphill) (down to the front of FIG. 16B). Force M4a which tries to turn the caster shaft generated at the position A force which tries to return this force against the force M3a which tries to turn the caster shaft.
M3c The weight of the wheelchair is received by the caster shaft, and the ground contact point with the traveling surface of the caster wheel, which is generated by following the inclination of the right-angled cross section in the traveling direction (downhill) (down to the front of the page in FIG. 16-d). Force M4c that attempts to turn the caster shaft at the position of radius L4 as the center Force that attempts to return this force against the force M3c that attempts to rotate the caster shaft.
P1 Grounding point between the caster wheel and the traveling surface P2 Grounding point between the auxiliary wheel and the traveling surface P3 Grounding point between the caster wheel and the traveling surface P4 Contact point between the caster wheel and the step T At the point P4 immediately below the caster shaft 130, A step contacting the outer periphery of the caster wheel 140. By the way, when the wheel diameter of the caster wheel 140 is 180 mm, the step T contacting the wheel immediately below the caster axis is about 23 mm.

Claims (3)

A caster wheel that rotates about a predetermined rotation axis, an auxiliary wheel arm that rotates about the rotation axis, and the auxiliary wheel arm further has a rotation shaft at an end, and the rotation axis is the center. A wheelchair front wheel caster comprising: an auxiliary wheel having a diameter smaller than that of the caster wheel that rotates in a straight line; and a spring member that biases the auxiliary wheel toward the ground. The wheelchair front wheel caster according to claim 1, wherein a ratio of a horizontal distance between a rotation shaft of the caster wheel and a caster shaft to a diameter of the caster wheel is 15% or less. A wheelchair comprising the front wheel caster for a wheelchair according to claim 1 or 2.

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