Multi-wheel wheelchair

Abstract

To provide a multi-wheeled wheelchair which can be used both indoors and outdoors, is lightweight, low-cost, and highly practical. The present invention is a multi-wheeled wheelchair comprising a body frame and front, middle and rear wheels provided on the left and right sides of the body frame, a first rocker link having a first end 16b supporting the front wheel 13, a first oscillating part 16a swingably connected to the body frame 11 and a first other end 16c, a second rocker link having a second end 17b supporting the rear wheel 14, a second oscillating part 17a swingably connected to the body frame 11 and a second other end 17c, and a link connection part 18 connecting the first other end 16c and the second other end 17c, the link connection part 18 having a middle wheel support part supporting the middle wheel 15 and displacing in conjunction with the oscillation of the first rocker link and the second rocker link.

Description

[Technical field]

[0001] The present invention relates to a multi-wheeled wheelchair equipped with multiple wheels, and in particular to a multi-wheeled wheelchair that has been improved so that it can accommodate running surfaces that have an upward convex slope change road or a downward concave slope change road with respect to the running direction. [Background technology]

[0002] In recent years, four-wheel and six-wheel electric wheelchairs have been commercially available in various regions as a means of mobility without relying on caregivers. Electric wheelchairs can be divided into two types: the handle type, which changes direction by operating the front wheels with a bar handle, and the joystick type, which has electric motors on the left and right and changes direction by the difference in rotation speed between the left and right motors. The joystick type is characterized by its high maneuverability, which is achieved by rotating the left and right drive motors in opposite directions. For this reason, the number of joystick type units shipped, which are highly convenient for use in hospitals and homes, has been steadily increasing (Ministry of Economy, Trade and Industry, 2008). Joystick type electric wheelchairs currently on the market are of two types: the four-wheel type, which has drive wheels on the front or rear wheels, and the six-wheel type, which has drive wheels in the center. Although the six-wheel system has the advantage of requiring less space for pivoting compared to the four-wheel system, the six-wheel system has the problem that the center wheel, which is the driving wheel, loses ground load when the road surface gradient changes, resulting in loss of braking and drive, and pitching behavior due to the front wheel lifting. Therefore, it is said that the handle-type and joystick-type four-wheel systems are suitable for outdoor use, while the joystick-type six-wheel system is suitable for indoor use. However, it is not realistic for one user to own multiple electric wheelchairs depending on the purpose. For this reason, there was a demand for an electric wheelchair that combines the high maneuverability inherent to a six-wheel electric wheelchair with the good ground contact of a four-wheel electric wheelchair.

[0003] Non-Patent Documents 1 and 2 disclose a wheeled mobile mechanism with a rocker-bogie link mechanism used in a Mars rover. The three wheels on one side are linked by a rocker link and a bogie link, and the left and right connecting rods connecting the left and right wheel rows are connected by a differential gear, thereby linking all six wheels on the left and right. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Yoji Kuroda, "Rotation Mechanism for Rough Terrain", Journal of the Robotics Society of Japan, Vol. 21, No. 5, 2003, pp. 477-479 [Non-Patent Document 2] Hayate Isoda and 4 others, "Unmanned exploration robot using rocker-bogie mechanism", Journal of the Japanese Society for Planetary Science, 2012, Vol. 21, No. 2, pp. 148-154 Summary of the Invention [Problem to be solved by the invention]

[0005] The characteristics of the rocker-bogie link mechanism adopted in Non-Patent Documents 1 and 2 are also favorable for six-wheel electric wheelchairs and can improve the grounding of six-wheel electric wheelchairs, but there are concerns about increased costs and mass due to the need to ensure the strength and rigidity of the components and the presence of a differential gear, etc. The rocker-bogie link, which is the precursor to the passive link mechanism, was developed for the purpose of traveling on rough roads on planets with a different gravity from Earth, so it is difficult in terms of cost-effectiveness to use this structure itself in commercially available electric wheelchairs.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a multi-wheeled wheelchair that can be used both indoors and outdoors, is lightweight, low-cost, and highly practical, by maintaining the advantages of six-wheeled electric wheelchairs, such as space-saving and maneuverability, while eliminating the disadvantages of ground contact. [Means for solving the problem]

[0007] The invention for solving the above problem is a multi-wheeled wheelchair comprising a body frame and front, middle and rear wheels provided on both the left and right sides of the body frame, a first rocker link having a first end supporting the axle of the front wheels, a first swinging part swingably connected to the body frame and a first other end facing the first end across the first swinging part, a second rocker link having a second end supporting the axle of the rear wheels, a second swinging part swingably connected to the body frame and a second other end facing the second one end across the second swinging part, and a link connecting part connecting the first other end and the second other end, wherein the link connecting part has a middle wheel support part supporting the axle of the middle wheels, and displaces in conjunction with the swinging of the first rocker link and the second rocker link.

[0008] According to this configuration, not only can the six-wheeled electric wheelchair have excellent effects such as a small minimum turning radius, high maneuverability, space saving, and no bias in risk of forward and backward rollover, but also the front, middle, and rear wheels can be kept in contact with the ground and run on a downward concave slope change road and an upward convex slope change road. Therefore, braking force and driving force are not lost even on a downward concave slope change road, pitching behavior can be prevented even on an upward convex slope change road, and it is possible to safely climb and descend slopes with a slope change road of 13 degrees or more, which exceeds the JIS standard. In addition, it can be manufactured lightweight and at low cost. This makes it possible to provide a highly practical multiple-wheeled wheelchair for both indoor and outdoor use.

[0009] Preferably, the link connection portion is a multiple-wheel wheelchair having a support portion and a support receiving portion connected to the support portion.

[0010] According to this configuration, the link connection portion can be realized by a combination of simple structures, which is advantageous in terms of cost and suitable for mass production.

[0011] Preferably, the support receiving portion has a pair of receiving surface portions, and the support portion is a multiple-wheel wheelchair that moves along the receiving surface portions in conjunction with the swinging of the first rocker link and the second rocker link.

[0012] According to this configuration, the support receiving portion has a receiving surface portion, and the support portion moves along the receiving surface portion in conjunction with the swinging of the first rocker link and the second rocker link, so that the support portion moves along the receiving surface portion, thereby enabling the front wheels, middle wheels, and rear wheels to smoothly follow the unevenness of the road. It is preferable that the receiving surface portion has a shape that extends linearly.

[0013] Preferably, the support receiving portion has a displacement suppression surface portion whose both ends are connected to both ends of the receiving surface portion, and the support portion is a multiple-wheeled wheelchair that suppresses displacement of the first rocker link and the second rocker link by contacting the displacement suppression surface portion.

[0014] According to this configuration, the support portion comes into contact with the displacement suppression surface portion, thereby suppressing the displacement of the first rocker link and the second rocker link, thereby ensuring stability of the driving posture even if the unevenness of the road becomes greater than expected.

[0015] Preferably, the wheelchair is a multiple-wheel type, in which the receiving surface portion and the displacement suppression surface portion cooperate to define a through hole.

[0016] According to this configuration, the receiving surface portion and the displacement suppression surface portion cooperate to define the through hole, so that the support receiving portion can have a simple structure. The through hole may have, for example, an elongated hole shape.

[0017] Preferably, the wheelchair is a multiple-wheel type wheelchair characterized by having a drive unit that drives the middle wheels.

[0018] According to this configuration, the drive unit is provided on the middle wheel where the largest wheel load can be set, so that running stability can be ensured. [Brief description of the drawings]

[0019] [Figure 1]FIG. 1(a) is a schematic diagram showing a side view of a four-wheeled electric wheelchair, and FIG. 1(b) is a schematic diagram showing a side view of a six-wheeled electric wheelchair (comparative example). [Diagram 2] 1(a) and 1(b) are schematic diagrams showing a four-wheel electric wheelchair and a six-wheel electric wheelchair having the same wheelbase length and tread width dimensions (comparison examples). [Diagram 3] (a) and (b) are schematic diagrams comparing the stability on downhill roads of a four-wheel electric wheelchair (rear-wheel drive) and a six-wheel electric wheelchair, both of which have the same wheelbase length and center of gravity (total center of gravity of the wheelchair and occupant) height (comparison example). [Figure 4] 1A and 1B are schematic diagrams comparing the stability on uphill roads of a four-wheel electric wheelchair (rear-wheel drive) and a six-wheel electric wheelchair, both of which have the same wheelbase length and center of gravity height (comparison example). [Diagram 5] 1(a) to 1(d) are schematic diagrams showing the wheel contact patterns of a four-wheel electric wheelchair (rear-wheel drive) and a six-wheel electric wheelchair, both of which have the same wheelbase length and center of gravity height, when the road surface slope changes to a concave downward shape (comparative example). [Figure 6] 1(a) to 1(f) are schematic diagrams showing the wheel contact patterns of a four-wheel electric wheelchair (rear-wheel drive) and a six-wheel electric wheelchair, both of which have the same wheelbase length and center of gravity height, when the road surface slope changes to an upward convex shape (comparative example). [Figure 7] FIG. 1 is a schematic diagram showing a multi-wheel type wheelchair according to an embodiment of the present invention as a six-wheel electric wheelchair. [Figure 8] FIG. 1 is a schematic diagram showing a state in which a multi-wheeled wheelchair according to an embodiment of the present invention is running on a downward concave slope switching road. [Figure 9] FIG. 1 is a schematic diagram showing a state in which a multi-wheeled wheelchair according to an embodiment of the present invention is traveling on an upwardly convex inclined switching road. [Figure 10]1A and 1B are schematic partial diagrams of a double rocker link mechanism according to an embodiment of the present invention, in which (a) shows a first rocker link and a link connection portion, (b) shows a second rocker link, and (c) shows the state in which the first rocker link mechanism and the second rocker link mechanism are connected at the link connection portion. [Figure 11] This is a modified version of a multi-wheel wheelchair. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Before describing the multiple-wheel wheelchair of the present invention, the background circumstances that motivated the present invention will be described in detail below. In recent years, four-wheel and six-wheel electric wheelchairs have been distributed on the market as a means of mobility without relying on a caregiver. Each type of wheelchair has wheels equipped with drive motors arranged on the left and right, and the drive motors are used to move straight, turn left and right, and turn. In this case, it is important in a narrow driving environment to rotate the left and right drive motors in opposite directions, that is, to enable pivoting by reversing the direction. In four-wheel and six-wheel electric wheelchairs, one has more advantageous characteristics than the other depending on the driving environment, and the degree of suitability varies depending on each characteristic.

[0021] FIG. 1(a) shows a schematic side view of a four-wheeled wheelchair with rear-wheel drive. Some four-wheeled wheelchairs have drive motors on the two front wheels Fe, but the four-wheeled wheelchair shown in the figure has drive motors on the two rear wheels Re. The driven wheels Dv of a four-wheeled wheelchair are caster wheels or wheels that roll in all directions (no direction). Whether the wheelchair is front-wheel drive or rear-wheel drive with the forward direction Fs, the center of gravity G of the vehicle and occupant combined is set near the drive wheel Df to ensure the transmission of braking force and drive force (traction) of the wheels on the road. The symbol Wh indicates the wheelbase length.

[0022] Figure 1(b) shows a schematic side view of a six-wheel wheelchair. In a six-wheel wheelchair, the front wheels Fe, middle wheels Me, and rear wheels Re are arranged in a line from front to back as shown in the figure when viewed from the side of the vehicle. The middle wheel Me is equipped with a drive motor and functions as a drive wheel. The front wheels Fe and rear wheels Re are driven wheels, and use caster wheels or wheels that roll in all directions (no direction). The center of gravity G, which combines the vehicle and occupant, is set at the middle wheel Me as the drive wheel, ensuring the transmission (traction) of the braking force and drive force of the wheels on the road.

[0023] Figures 2(a) and (b) show the front-to-rear length Fu of the wheelchair and the minimum turning radius Md of the pivot turn for a four-wheeled electric wheelchair and a six-wheeled electric wheelchair, respectively, with the same wheelbase length Wh and tread width Tw. The minimum turning radius Md of the six-wheeled electric wheelchair is smaller than that of the four-wheeled electric wheelchair. The four-wheeled electric wheelchair has a longer front-to-rear dimension (total length Fu) from the front end of the front wheel Fe to the rear end of the rear wheel Re compared to the six-wheeled electric wheelchair. For this reason, the six-wheeled electric wheelchair is more suitable for small environments such as ordinary homes compared to the four-wheeled electric wheelchair, and is mainly used indoors. The symbol Dj indicates the difference in overall length between the four-wheeled electric wheelchair and the six-wheeled electric wheelchair, the symbol Cf indicates the midpoint of the drive wheels, and the symbol Gf indicates the center of gravity of the entire vehicle and the occupant.

[0024] Figures 3(a) and (b) compare the stability of a four-wheeled electric wheelchair (rear-wheel drive) and a six-wheeled electric wheelchair, both of which have the same wheelbase length Wh and height Hk of the center of gravity G of the entire wheelchair and occupant, on a downhill road (descent angle Ae). If the intersection Jk of the vertical line Lg from the center of gravity G of the occupant U and the entire wheelchair and the road S falls outside the wheelbase length Wh section, the wheelchair will roll over.

[0025] In a four-wheel electric wheelchair, the center of gravity is located at the rear when traveling on flat ground, so the forward rollover limit of a four-wheel electric wheelchair on a downhill road is high (see Figure 3(a)). In contrast, in the case of a six-wheel electric wheelchair, the forward rollover limit on the same downhill road as described above is less favorable than that of a four-wheel electric wheelchair (see Figure 3(b)). Note that the symbol Hf indicates the section distance between the contact point Jx of the front wheel Fe with the road S and the intersection point Jk as the non-projecting length.

[0026] Figures 4(a) and (b) show the state of the movement of the center of gravity position of the wheelchair with respect to the wheelbase length Wh for a four-wheel electric wheelchair and a six-wheel electric wheelchair on an uphill road with the same inclination angle (climbing slope angle Ak). From the position of the intersection point Jk of both wheelchairs, it can be seen that the six-wheel electric wheelchair has a greater margin in the backward rollover limit than the four-wheel electric wheelchair. Therefore, in order to make the forward and backward rollover limit of the four-wheel electric wheelchair the same as that of the six-wheel electric wheelchair, the dimension of the wheelbase length Wh of the four-wheel electric wheelchair needs to be longer than that of the six-wheel electric wheelchair. As a result, the four-wheel electric wheelchair has a larger front-to-rear length, which makes it suitable for a wide range of driving environments, and is one of the reasons why the four-wheel electric wheelchair is suitable for outdoor use. The symbol Hs indicates the section distance between the ground contact point Jx of the front wheels Fe on the road S and the intersection point Jk as the non-projecting length.

[0027] Figures 5(a)-(d) show the contact state of the wheels when the road surface slope changes to a concave downward shape for a four-wheeled electric wheelchair (rear-wheel drive) and a six-wheeled electric wheelchair, both of which have the same wheelbase length Wh and height Hk of the center of gravity G. The four-wheeled electric wheelchair can travel with all wheels in contact with the road S, as shown in Figures 5(a) and (c), whereas the six-wheeled electric wheelchair loses contact with the road S, as shown in Figures 5(b) and (d).

[0028] In the latter case, where the middle wheel Me loses contact with the ground, the braking and driving forces will not be effective on the road S, which can occur on outdoor sidewalks or at step locations, which is one of the reasons why a four-wheel electric wheelchair is more suitable for traveling outdoors.

[0029] Figures 6(a)-(f) show the contact state of the wheels when the road surface slope changes to an upward convex shape for a four-wheeled electric wheelchair (rear-wheel drive) and a six-wheeled electric wheelchair, both of which have the same wheelbase length Wh and height Hk of the wheelchair's center of gravity G. The four-wheeled electric wheelchair can travel with all wheels in contact with the road S, as shown in Figures 6(a) and (c), whereas the six-wheeled electric wheelchair loses contact with the road S, as shown in Figures 6(b) and (d).

[0030] The front wheel Fe, which has lost contact with the ground and is suspended in the air, exhibits a sudden pitching behavior (vertical shaking) relative to the roadway S as the middle wheel Me, which has moved forward Fs, overcomes the sloped road surface, as shown in Figures 6(e) and (f). This pitching behavior does not affect the driving performance, but it may cause anxiety to the seated occupant U. On roads, road surface slopes that change to an upward convex shape are common outdoors, which is why four-wheeled electric wheelchairs are suitable for driving outdoors.

[0031] The advantages and disadvantages of the four-wheel electric wheelchair (rear-wheel drive) and six-wheel electric wheelchair mentioned above can be summarized as follows: In other words, if a six-wheel electric wheelchair and a four-wheel electric wheelchair have the same wheelbase length Wh, the six-wheel electric wheelchair has the advantage over the four-wheel electric wheelchair in terms of the minimum turning radius Md in narrow spaces and the length dimension from the front to the rear of the wheelchair (total length).

[0032] In addition, for downhill and uphill driving roads, the forward and rearward rollover limits of a six-wheel electric wheelchair are not biased, so if a six-wheel electric wheelchair and a four-wheel electric wheelchair have the same wheelbase length Wh, the forward and rearward rollover limits of the six-wheel electric wheelchair will be higher than those of a four-wheel electric wheelchair. On the other hand, a six-wheel electric wheelchair has the disadvantage that the ground contact of the middle wheel Me is lost when the road surface slopes to a concave shape, and the braking force and driving force become ineffective.

[0033] In addition, six-wheel electric wheelchairs have a problem in that, although it does not affect driving performance, the front wheels Fe or rear wheels Re lose contact with the ground when the road surface slope changes to an upward convex shape, causing the wheelchair to exhibit pitching behavior, causing it to sway rapidly in the forward and backward directions. For this reason, there has been a demand for the emergence of a six-wheel electric wheelchair that solves these problems and shortcomings while also having the inherent characteristics of a six-wheel electric wheelchair, such as a small minimum turning radius Md, high maneuverability, and space-saving features.

[0034] One such six-wheel electric wheelchair is one that uses a rocker-bogie link mechanism, which is a conventional passive link mechanism. The middle and rear wheels on one side are connected by a bogie link, and the bogie link and the front wheels are connected by a rocker link, and the left and right connecting rods connecting the left and right wheel rows are connected by a differential gear, resulting in a six-wheel drive, six-wheel steering system. The characteristics of this type of rocker-bogie link mechanism are also favorable for six-wheel electric wheelchairs, but there are concerns about the increased cost and mass if it is used in commercially available wheelchairs, due to the need to ensure the strength and rigidity of the components and the presence of a differential gear.

[0035] Now that the background circumstances that motivated the present invention have been described in detail, the present invention will be described below. The multiple-wheeled wheelchair of the present invention proposes and employs a double rocker link mechanism, which is a novel passive link mechanism. In the double rocker link mechanism, the front wheels and the middle wheels, and the middle wheels and the rear wheels are all connected by rocker links, and the two rocker links are connected at the middle wheel position so that only vertical displacement can be transmitted. In the rocker-bogie link mechanism, one end attached to the rocker link attached to the body frame is connected to the center of the bogie link. In other words, the rocker link and the bogie link are connected in series to associate three wheels on one side. On the other hand, in the double rocker link mechanism of the multiple-wheeled wheelchair of the present invention, two rocker links, each attached to the body frame, are connected via a link connecting part to associate three wheels on one side.

[0036] A multi-wheel wheelchair 10 according to an embodiment of the present invention will now be described.

[0037] An embodiment of the present invention will be described below with reference to Figs. 7 to 10. As shown in Fig. 7, a multiple-wheeled wheelchair 10 according to an embodiment of the present invention has a seat 12 attached to a body frame 11. In front of the seat 12, that is, at positions on both the left and right sides of the body frame 11 in the forward direction T, which is the front of the multiple-wheeled wheelchair 10, there are provided a front wheel 13, a rear wheel 14, and a middle wheel 15 disposed between the front wheel 13 and the rear wheel 14. This makes the multiple-wheeled wheelchair 10 a six-wheeled electric wheelchair. In the following drawings, the front wheel 13, the rear wheel 14, and the middle wheel 15 are shown as schematic diagrams of only one side, not both the left and right sides, for convenience.

[0038] The middle wheel 15 is set to have a larger diameter than both the front wheels 13 and the rear wheels 14, and the middle wheel 15 serves as a driving wheel and is driven to rotate along the running path St, causing the front wheels 13 and the rear wheels 14 to rotate along the running path St as driven wheels.

[0039] In the following description, the front wheels 13 and the rear wheels 14 are described as having the same diameter, but they may have different diameters. In addition, the middle wheels 15, which are driving wheels, are preferably larger in diameter than the front wheels 13 and the rear wheels 14, but this is not essential. Although not shown, the electric motor 40 is started by operating a joystick provided as a control stick. The electric motor 40 is started to drive the middle wheels 15 as driving wheels, thereby enabling the multiple-wheeled wheelchair 10 to proceed, stop, turn left and right, and turn left and right. The electric motor 40 is attached to each of the left and right middle wheels 15. By adjusting the driving force of the electric motor 40 attached to each of the left and right middle wheels 15, i.e., the rotation speed of the left and right middle wheels 15, the multiple-wheeled wheelchair 10 can turn left and right, and can also make a pivot turn.

[0040] The multiple-wheel wheelchair 10 has a pair of first links 16 on each side, which are first rocker links connecting the front wheels 13, and a pair of second links 17 on each side, which are second rocker links connecting the rear wheels 14. The first links 16, the second links 17, and a link connecting part 18, which will be described later, form a double rocker link mechanism 21.

[0041] The first link 16 includes a first end portion 16b, a first other end portion 16c, and a first swinging portion 16a. The first link 16 is swingably attached to the body frame 11 by the first swinging portion 16a. The first end portion 16b extends in a direction toward the axle of the front wheel 13 and is connected to the axle of the front wheel 13. The first other end portion 16c forms a certain angle with the first end portion 16b and extends in a direction toward the axle of the rear wheel 14 and is connected to the link connecting portion 18.

[0042] The second link 17 includes a second end portion 17b, a second other end portion 17c, and a second swinging portion 17a. The second link 17 is swingably attached to the body frame 11 by the second swinging portion 17a. The second end portion 17b extends toward the axle of the rear wheel 14 and is connected to the axle of the rear wheel 14. The second other end portion 17c forms a certain angle with the second end portion 17b and extends toward the axle of the front wheel 13 and is connected to the link connecting portion 18.

[0043] The first other end 16c and the second other end 17c are connected via a link connection part 18 that correlates their respective swinging displacements within a specific swing angle range. The link connection part 18 has a middle wheel support part 18a that supports the axle of the middle wheel 15, and the axle of the middle wheel 15 is rotatably connected to the link connection part 18. As a result, the front wheels 13, the rear wheels 14, and the middle wheel 15 are displaced in conjunction with each other, and can swing in a state following the unevenness of the traveling road St.

[0044] The link connecting portion 18 is composed of a roller pin 19 (support portion) connected to the second other end portion 17c, and a support receiving portion 20 connected to the first other end portion 17b.

[0045] 10, the support receiving portion 20 has a pair of receiving surface portions 20a, 20a, and a displacement suppression surface portion 20b connected to the ends of the pair of receiving surface portions 20a, 20a. The receiving surface portion 20a and the displacement suppression surface portion 20b cooperate to define an elongated through hole 30. The receiving surface portion 20a defines a surface that extends linearly in the traveling direction T of the multiple-wheeled wheelchair 10.

[0046] When all of the front wheels 13, rear wheels 14, and middle wheels 15 are in contact with the roadway St, the roller pin 19 is in contact with one of the pair of receiving surfaces 20a, 20a, and is disposed with a small gap from the other receiving surface 20a. When any of the front wheels 13, rear wheels 14, and middle wheels 15 passes over the unevenness of the roadway St, the first link 16 and the second link 17 attempt to swing independently, but the roller pin 19 rolls or slides on the receiving surface 20a, so that the swinging of the first link 16 and the second link 17 are related to each other. That is, the roller pin 19 moves while being able to roll on the receiving surface 20a of the support receiving portion 20, so that the displacements of the first link 16 and the second link 17 can be transmitted to each other in accordance with the swinging displacements of the first link 16 and the second link 17. (See Figs. 8 and 9.)

[0047] For example, when comparing the driving state of Fig. 7 with the driving states of Fig. 8 and Fig. 9, the proportion of the vertical load W shared by the front wheels 13, rear wheels 14, and middle wheels 15 is the same in each state. In other words, the middle wheels 15 can exert a substantially constant driving force without being affected by the unevenness of the road St.

[0048] The ground load of the middle wheel 15 required for traction may be appropriately determined taking into consideration the driving conditions. For example, if the total weight of the wheelchair and occupant U is W, when a:b:c:d=1:1:1:1 (see FIG. 7), the vertical load at the first swinging part 16a and the second swinging part 17a is 1 / 2W, and the vertical loads on the front wheel 13 and the rear wheel 14 are 1 / 4W, respectively. The vertical load on the middle wheel 15 is 1 / 2W, which is the sum of the vertical load 1 / 4W from the first link 16 and the vertical load 1 / 4W from the second link 17, and the ground load of the middle wheel 15 required for traction can be obtained.

[0049] When the road surface St exceeds a predetermined unevenness, the roller pin 19 comes into contact with the displacement suppression surface portion 20b. This suppresses the swinging displacement of the first link 16 and the second link 17. If the vehicle continues to move forward or backward under this condition, the middle wheel 15 will separate from the road surface St and lose driving force. In other words, the displacement suppression surface portion 20b plays a role in preventing the vehicle from traveling under harsh conditions.

[0050] When the travel path St has successive unevenness, the first link 16 and the second link 17 repeatedly swing in different directions. As a result, the roller pin 19 tries to displace in the direction in which the receiving surface 20a extends while in contact with one of the pair of receiving surfaces 20a. This stabilizes the behavior of the first link 16 and the second link 17.

[0051] In this embodiment, the roller pin 19 that is rotatably connected is exemplified, but a pin structure that slides relative to the support receiving portion 20 may also be used. In this case, however, it is necessary to make the sliding resistance sufficiently small.

[0052] [Effects of the embodiment] A double rocker link mechanism 21 is formed by connecting the first link 16, which is the first rocker link, and the second link 17, which is the second rocker link, with a link connection portion 18, and the up and down movement of the front wheel 13 is linked to the up and down movement of the rear wheel 14 via the double rocker link mechanism 21.

[0053] Regarding the definition of up and down in the up and down movements of the front wheels 13 and the rear wheels 14, the direction perpendicular to the horizontal direction F when the multiple-wheeled wheelchair 10 is placed on a horizontal plane as shown in Fig. 7 is defined as the virtual vertical direction E of the multiple-wheeled wheelchair 10 fixed to the multiple-wheeled wheelchair 10, and upward movement relative to the body frame 11 based on the virtual vertical direction E is defined as upward movement, and downward movement relative to the body frame 11 is defined as downward movement. For example, when switching from an uphill slope to a horizontal plane, according to this definition, the downward movement of the front wheels 13 and the downward movement of the rear wheels 14 will be linked at the point where the slope changes.

[0054] For this reason, on the downward concave inclined transition road S3 shown in Fig. 8, the front wheels 13 and rear wheels 14 rotate upward according to the inclination angles ω1 and ω2, so that the center wheel 15, which is the driving wheel, is in a ground contact state even on the downward concave inclined transition road S3, and the braking force and driving force on the slope can be advantageously applied. Note that, on the downward concave inclined transition road S3 shown in Fig. 8, the ground contact load of the center wheel 15 is thought to change slightly from the horizontal arrangement shown in Fig. 7, but the change in the ground contact load is extremely small, and the ground contact load can be sufficient for braking and driving.

[0055] In addition, on the upward convex inclination switching road S4 shown in Fig. 9, the front wheels 13 and rear wheels 14 rotate downward according to the inclination angles ω3 and ω4, so that the middle wheel 15 as well as the front wheels 13 and rear wheels 14 are in a ground contact state, and the braking force and driving force for the slope can be applied, and when the multiple-wheeled wheelchair 10 travels in the traveling direction T, it is possible to prevent the front wheels 13 from losing contact with the ground and causing pitching (vertical shaking) even on a road surface inclination that switches to an upward convex shape. In addition, on the upward convex inclination switching road S4 shown in Fig. 9, it is thought that the ground load of the middle wheel 15 changes slightly from the horizontal arrangement shown in Fig. 7, but the change in the installation load is extremely small, and the ground load can be sufficient for braking and driving.

[0056] In this way, the multi-wheeled wheelchair 10 according to an embodiment of the present invention not only exhibits the excellent effects inherent to a six-wheel electric wheelchair, such as a small minimum turning radius Md, high maneuverability, and space-saving characteristics, but can also be driven on the downward concave slope switching road S3 and the upward convex slope switching road S4 with the front wheels 13, middle wheels 15, and rear wheels 14 each kept in contact with the ground.

[0057] This makes it possible to maintain the advantages of a six-wheeled electric wheelchair while eliminating its disadvantages, making the six-wheeled electric wheelchair applicable not only for indoor use but also for outdoor use.

[0058] In this embodiment, the link connecting part 18 is configured by the rotatable roller pin 19 and the support receiving part 20 in which the through hole 30 is defined, but this is not limited to this. Other configurations may be adopted as long as the same function is obtained. For example, as shown in FIG. 11, the link connecting part 218 may be configured by a U-shaped support receiving part 220 and a roller pin 219 that rolls or slides on the U-shaped support receiving part. In this case, the axle of the middle wheel 15 may be supported by the roller pin 219.

[0059] The multiple-wheel wheelchair 10 of this embodiment is a six-wheel electric wheelchair, but it is not limited to an electric wheelchair and may be a manual wheelchair. Also, the wheelchair can be effectively used by a healthy person as well as a person who needs care as the occupant U. [Industrial Applicability]

[0060] The multiple-wheeled wheelchair of the present invention maintains the advantages of the six-wheeled electric wheelchair while eliminating the disadvantages, and the six-wheeled electric wheelchair can be used not only indoors but also outdoors, making it possible to provide a safe and practical wheelchair at a low cost and with great industrial applicability. In addition, it will stimulate demand from related parties who are aware of the convenience and usefulness of the six-wheeled electric wheelchair, and contribute to the promotion of manufacturing-related industries through the revitalization of distribution in the market. [Explanation of symbols]

[0061] 10. Multi-wheel wheelchair 11 Body frame 13 Front wheel 14 Rear wheel 15...middle wheel 16···First link (first rocker link) 17 Second link (second rocker link) 16a First swinging part 17a Second swinging part 16b... First end 16c...1st of other end 17b...Second end 17c...2nd of The other end 18... Link connection part 19... Roller pin 20... Support receiving part 20a... Receiving surface part 20b... Displacement suppression surface part 30... Through hole

Claims

1. A multi-wheel wheelchair comprising a body frame and front, middle and rear wheels provided on both the left and right sides of the body frame, a first rocker link having a first end portion supporting an axle of the front wheel, a first swinging portion swingably connected to the body frame, and a first other end portion opposed to the first end portion across the first swinging portion; a second rocker link having a second one end supporting an axle of the rear wheel, a second swinging part swingably connected to the body frame, and a second other end opposed to the second one end across the second swinging part; A link connection portion having a center wheel support portion that supports the center wheel, the link connection portion has a support portion which is a roller pin connected to either the first other end portion or the second other end portion, and a support receiving portion which is connected to the other of the first other end portion or the second other end portion, The support receiving portion has a pair of receiving surface portions, A multi-wheeled wheelchair in which, when the link connection portion is displaced in conjunction with the swinging of the first link and the second link, the support receiving portion moves along the receiving surface portion.

2. The support receiving portion has a displacement suppression surface portion, both ends of which are connected to both ends of the receiving surface portion, 2. The multi-wheel wheelchair according to claim 1, wherein the support portion suppresses displacement of the first rocker link and the second rocker link by contacting the displacement suppression surface portion.

3. The multi-wheel wheelchair according to claim 2 , wherein the receiving surface portion and the displacement suppression surface portion cooperate to define a through hole.

4. The multi-wheeled wheelchair according to claim 1 , further comprising a drive unit for driving the middle wheels.

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