Multi-wheel wheelchair

Abstract

The invention provides a multi-wheel wheelchair which can be applied indoors and outdoors, and is light in weight, low in cost and high in practicability. This multi-wheeled wheelchair is provided with a vehicle body frame, and front wheels, middle wheels, and rear wheels provided at the left and right sides of the vehicle body frame, and is also provided with: a first rocker arm link having a first end (16b) that pivotally supports the front wheels (13), a first swing part (16a) that is swingably connected to the vehicle body frame (11), and a first other end (16c); a second rocker link having a second end portion (17b) that pivotally supports the rear wheel (14), a second swing portion (17a) that is swingably connected to the vehicle body frame (11), and a second other end portion (17c); and a link connecting portion (18) connected to the first other end portion (16c) and the second other end portion (17c), the link connecting portion (18) having a center wheel shaft support portion for axially supporting the center wheel (15), and being displaced in conjunction with the swing of the first rocker arm link and the second rocker arm link.

Description

Technical Field

[0001] The present invention relates to a multi-wheeled wheelchair having a plurality of wheels, and in particular to a multi-wheeled wheelchair which has been improved to be able to cope with a driving road surface having an upward convex inclined switching path and a downward concave inclined switching path in the driving direction. Background Art

[0002] In recent years, as a device that can be moved without relying on nursing staff, 4-wheeled and 6-wheeled electric wheelchairs are sold in various places. Among electric wheelchairs, there are wheelchairs called handle-type wheelchairs that change direction by operating the front wheel with a lever-type handle, and wheelchairs called joystick-type wheelchairs that have electric motors on the left and right and change direction by the speed difference of each motor. The joystick-type is characterized by high small turning ability brought about by the rotation in place (center turn) that reverses the left and right drive motors. Therefore, the number of joystick-type electric wheelchairs shipped from the factory with high convenience in hospitals and homes has been steadily increasing (Ministry of Economy, Trade and Industry of Japan, 2008). Among the joystick-type electric wheelchairs currently on sale, there are two types: a 4-wheel type with a drive wheel on the front or rear wheel, and a 6-wheel type with a drive wheel on the center wheel. Although the details will be described later, the 6-wheel method is advantageous in that it occupies a smaller area when turning in place than the 4-wheel method. On the other hand, when there is a switch in the road surface inclination on the driving road, the 6-wheel vehicle has the problem that the driving wheel, that is, the central wheel loses the ground load and the braking and driving do not work, and the problem of pitching behavior caused by the floating of the front wheel, which will be described in detail later. Therefore, the handle type and the joystick type 4-wheel method are suitable for outdoor use, and the joystick type 6-wheel method is suitable for indoor use. However, it is not realistic for a user to own multiple electric wheelchairs according to their purpose. Therefore, an electric wheelchair is desired, which has both the high small turning performance originally possessed by the 6-wheel electric wheelchair and the good ground contact performance possessed by the 4-wheel electric wheelchair.

[0003] Non-patent documents 1 and 2 disclose a wheel-type moving mechanism with a rocker-bogie linkage mechanism for a Mars rover. The three wheels on one side are connected by a rocker link and a bogie link, and the left and right connecting rods connecting the left and right wheel trains are connected by a differential gear, thereby connecting all six left and right wheels.

[0004] Non-patent document 1: Yoji Kuroda, "Uneven Ground Moving Mechanism", Journal of the Robotics Society of Japan, Vol. 21, No. 5, 2003, pp. 477-479

[0005] Non-patent document 2: Isada Sa, and four others, "Unmanned exploration robot using a rocker-bogie mechanism", Journal of the Planetary Science Society of Japan (Journal of the Planetary Science Society of Japan), 2012, Vol. 21, No. 2, pp. 148-154

[0006] The characteristics of the rocker-bogie linkage mechanism used in non-patent documents 1 and 2 are also preferred for 6-wheel electric wheelchairs, and can improve the ground contact of 6-wheel electric wheelchairs, but there are concerns about the increase in cost and mass due to the strength and rigidity of the components and the existence of differential gears. The rocker-bogie linkage, which is the predecessor of the passive linkage mechanism, was developed for the purpose of driving on uneven roads on planets with different gravity from the earth, so it is difficult to use such a structure itself to sell electric wheelchairs in terms of cost performance. Summary of the invention

[0007] The present invention has been completed in view of the above-mentioned problems, and its purpose is to provide a multi-wheeled wheelchair that maintains the advantages of a 6-wheeled electric wheelchair in terms of space saving and high turning ability, and eliminates the disadvantages related to ground contact, so that one wheel can be suitable for both indoors and outdoors, and is lightweight, low-cost, and highly practical.

[0008] The invention for solving the above-mentioned problems is a multi-wheeled wheelchair, which comprises a body frame, and front wheels, middle wheels and rear wheels arranged at left and right sides of the body frame, and comprises: a first rocker arm link having a first end portion axially supporting the axle of the front wheel, a first swinging portion connected to the body frame in a swingable manner, and a first other end portion opposite to the first end portion across the first swinging portion; a second rocker arm link having a second end portion axially supporting the axle of the rear wheel, a second swinging portion connected to the body frame in a swingable manner, and a second other end portion opposite to the second first end portion across the second swinging portion; and a link connecting portion connected to the first other end portion and the second other end portion, the link connecting portion having a middle wheel axle supporting portion axially supporting the axle of the middle wheel, and the above-mentioned link connecting portion displaces in conjunction with the swinging of the first rocker arm link and the second rocker arm link.

[0009] According to this structure, the excellent effects originally possessed by a 6-wheel electric wheelchair are achieved, such as a small minimum turning radius, high turning performance, space saving, and no deviation in the risk of tipping over forward or backward. Moreover, even in a concave inclined switching path and an upper convex inclined switching path, the front wheel, the middle wheel, and the rear wheel can be respectively maintained in a grounded state for driving. Therefore, even in a concave inclined switching path, the braking force and the driving force will not be lost, and even in an upper convex inclined switching path, the pitching behavior can be prevented, and even in an inclined switching path exceeding 13 degrees of the JIS specification, it is possible to safely go up and downhill. In addition, it can be manufactured lightly and at low cost. Thus, a multi-wheeled wheelchair with high practicality for indoor and outdoor use can be provided.

[0010] The multi-wheeled wheelchair preferably has a link connection portion including: a support portion; and a support receiving portion connected to the support portion.

[0011] According to this structure, the link connection portion can be realized by a combination of simple structures, which is cost-effective and suitable for mass production.

[0012] The multi-wheeled wheelchair preferably has a pair of receiving surface parts in the supporting receiving part, and the supporting part is linked with the swing of the first rocker arm link and the second rocker arm link to move along the receiving surface parts.

[0013] According to this structure, the support receiving portion has a receiving surface portion, and the support portion moves along the receiving surface portion in conjunction with the swing of the first rocker link and the second rocker link, so that the front wheel, the middle wheel, and the rear wheel can smoothly follow the unevenness of the driving road by the support portion moving along the receiving surface portion. Preferably, the receiving surface portion is a shape extending in a straight line.

[0014] The multi-wheeled wheelchair preferably has a displacement suppression surface on the supporting receiving portion, the two ends of the displacement suppression surface are connected to the two ends of the receiving surface, and the supporting portion suppresses the displacement of the first rocker arm link and the second rocker arm link by contacting the displacement suppression surface.

[0015] According to this configuration, since the support portion contacts the displacement suppressing surface portion, displacement of the first rocker link and the second rocker link is suppressed, stability of the running posture can be ensured even when the unevenness of the running road is larger than expected.

[0016] The multi-wheeled wheelchair preferably has a through hole defined in a manner that the receiving surface and the displacement suppression surface cooperate with each other.

[0017] According to this structure, the receiving surface portion and the displacement suppression surface portion cooperate to define the through hole, so that the support receiving portion can be made into a simple structure. As the shape of the through hole, a long hole shape or the like can be exemplified.

[0018] The multi-wheeled wheelchair is preferably characterized by comprising a driving unit for driving the middle wheels.

[0019] According to this configuration, since the driving unit is provided on the middle wheel where the wheel load can be set to the maximum, the driving stability can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 (a) is a schematic diagram schematically showing a side view of a four-wheel electric wheelchair, and (b) is a schematic diagram schematically showing a side view of a six-wheel electric wheelchair (comparative example).

[0021] Figure 2 (a) and (b) are schematic diagrams showing a four-wheel electric wheelchair and a six-wheel electric wheelchair having the same wheelbase length and tread width (comparative example).

[0022] Figure 3(a) and (b) are schematic diagrams comparing the stability on a downhill road of a 4-wheel electric wheelchair (rear-wheel drive) and a 6-wheel electric wheelchair having the same wheelbase length and center of gravity (the center of gravity of the wheelchair and the occupant combined) height (comparison example).

[0023] Figure 4 (a) and (b) are schematic diagrams comparing the stability on an uphill road of a 4-wheel electric wheelchair (rear-wheel drive) and a 6-wheel electric wheelchair having the same wheelbase length and center of gravity height (comparison example).

[0024] Figure 5 (a) to (d) are schematic diagrams (comparison examples) showing the ground contact state of a 4-wheeled electric wheelchair (rear-wheel drive) and a 6-wheeled electric wheelchair having the same wheelbase length and center of gravity height, in which the wheels are inclined relative to a concave-shaped driving road surface.

[0025] Figure 6 (a) to (f) are schematic diagrams (comparison examples) showing the ground contact state of a 4-wheeled electric wheelchair (rear-wheel drive) and a 6-wheeled electric wheelchair having the same wheelbase length and center of gravity height, in which the wheels are inclined relative to the convex shape of the driving road surface.

[0026] Figure 7 This is a schematic diagram showing the multi-wheeled wheelchair according to the embodiment of the present invention as a six-wheeled electric wheelchair.

[0027] Figure 8 This is a schematic diagram schematically showing a state of a multi-wheeled wheelchair according to an embodiment of the present invention when traveling on a concave inclined switching road.

[0028] Fig. 9 This is a schematic diagram schematically showing a state of a multi-wheeled wheelchair according to an embodiment of the present invention when traveling on an upward convex inclined switching road.

[0029] Fig.10 It is a schematic partial schematic diagram of a double rocker arm linkage mechanism according to an embodiment of the present invention, wherein (a) represents a first rocker arm linkage and a linkage connection portion, (b) represents a second rocker arm linkage, and (c) represents a state in which the first rocker arm linkage mechanism and the second rocker arm linkage mechanism are connected by a linkage connection portion.

[0030] Fig.11 It is a modified example of a multi-wheeled wheelchair. DETAILED DESCRIPTION

[0031] Here, before explaining the multi-wheeled wheelchair of the present invention, the background situation that serves as the motivation for the present invention will be described in detail below. In recent years, 4-wheeled and 6-wheeled electric wheelchairs have been circulating in the market as devices that can move without relying on a caregiver. In either case, wheels with drive motors are arranged on the left and right, and the drive motors are used to drive forward, turn left, turn right, and rotate. In this case, by rotating the left and right drive motors in opposite directions, that is, reversing, it is possible to turn in place, which is an important matter for a narrow driving environment. The 4-wheeled and 6-wheeled electric wheelchairs each have characteristics that one is more advantageous than the other depending on the driving environment, and there are situations where the suitability of the application is different according to each characteristic.

[0032] Figure 1 (a) schematically shows the side view of a rear-wheel drive 4-wheel wheelchair. Among 4-wheel wheelchairs, there are also wheelchairs with drive motors installed on the two front wheels Fe, but the 4-wheel wheelchair shown in the figure has drive motors installed on the two rear wheels Re. The driven wheels Dv of the 4-wheel wheelchair use casters (caster wheels) or wheels that can rotate in all directions (no direction). Both front-wheel drive and rear-wheel drive with the front Fs as the direction of travel ensure the transmission (traction) of the braking force and driving force of the wheels to the travel path by setting the center of gravity G of the vehicle and the occupants together near the drive wheel Df. In addition, the symbol Wh represents the wheelbase length.

[0033] Figure 1 (b) schematically shows the side view of a 6-wheeled wheelchair. In the 6-wheeled wheelchair, when viewed from the side of the vehicle, the front wheel Fe, the middle wheel Me and the rear wheel Re are arranged in a front-to-back arrangement as shown in the figure. A driving motor is provided in the middle wheel Me to function as a driving wheel. The front wheel Fe and the rear wheel Re are driven wheels, using casters or wheels that can rotate in all directions (no direction). By setting the center of gravity G of the vehicle and the occupants together on the middle wheel Me as the driving wheel, the transmission (traction) of the braking force and the driving force of the wheel to the travel path is ensured.

[0034] For a 4-wheeled electric wheelchair and a 6-wheeled electric wheelchair with the same wheelbase length Wh and tread width Tw, Figure 2(a) and (b) respectively show the front-to-back length Fu of the wheelchair and the minimum rotation radius Md by turning in place. The minimum rotation radius Md of a 6-wheel electric wheelchair is smaller than that of a 4-wheel electric wheelchair. Compared with a 6-wheel electric wheelchair, the front-to-back dimension (total length Fu) from the front end of the front wheel Fe to the rear end of the rear wheel Re of a 4-wheel electric wheelchair is longer. Therefore, a 6-wheel electric wheelchair is more suitable for narrow environments such as ordinary homes than a 4-wheel electric wheelchair, which is an important factor for mainly using it indoors. In addition, the symbol Dj represents the difference in total length between a 4-wheel electric wheelchair and a 6-wheel electric wheelchair, the symbol Cf represents the midpoint of the drive wheel, and Gf represents the center of gravity of the vehicle and the occupant combined.

[0035] Regarding a 4-wheel electric wheelchair (rear-wheel drive) and a 6-wheel electric wheelchair having the same wheelbase length Wh and the height Hk of the center of gravity G of the entire wheelchair and the occupant, Figure 3 (a) and (b) compare the stability of each wheelchair on a downhill road (downhill angle Ae). If the intersection Jk of the vertical line Lg passing through the center of gravity G of the occupant U and the entire wheelchair and the travel path S is out of the wheelbase length Wh interval, the wheelchair will tip forward.

[0036] In a 4-wheeled electric wheelchair, the center of gravity is at the rear when traveling on flat ground, so the forward tipping limit of a 4-wheeled electric wheelchair on a downhill road is high (refer to Figure 3 In contrast, in the case of a 6-wheel electric wheelchair, the forward tipping limit on the same downhill road as above is unfavorable compared to a 4-wheel electric wheelchair (refer to Figure 3 (b)). In addition, the symbol Hf represents the distance between the ground contact point Jx of the front wheel Fe with respect to the travel path S and the intersection point Jk as a non-protruding length.

[0037] Regarding 4-wheeled electric wheelchairs and 6-wheeled electric wheelchairs on an uphill road with the same inclination angle (uphill angle Ak), Figure 4 (a) and (b) show the movement of the center of gravity of the wheelchair relative to the wheelbase length Wh. Observing from the position of the intersection Jk of the two wheelchairs, it can be seen that the 6-wheel electric wheelchair has a wider limit on the backward tipping over than the 4-wheel electric wheelchair. Therefore, in order to make the forward and backward tipping over limits of the 4-wheel electric wheelchair the same as those of the 6-wheel electric wheelchair, it is necessary to make the wheelbase length Wh of the 4-wheel electric wheelchair longer than that of the 6-wheel electric wheelchair. As a result, the front-to-back length of the 4-wheel electric wheelchair becomes longer, which is suitable for a wide driving range environment, and is one of the important factors for the 4-wheel electric wheelchair to be suitable for outdoor use. In addition, the symbol Hs represents the interval distance between the grounding point Jx of the front wheel Fe relative to the driving road S and the intersection Jk as a non-protruding length.

[0038] Regarding a 4-wheeled electric wheelchair (rear-wheel drive) and a 6-wheeled electric wheelchair having the same wheelbase length Wh and height Hk of the center of gravity G, Figure 5 (a) to (d) show the ground contact state of the wheel with respect to the concave shape of the running road surface. Figure 5 As shown in (a) and (c), the 6-wheel electric wheelchair can travel with all wheels in contact with the driving road S. Figure 5 As shown in (b) and (d), the middle wheel Me is separated from the ground contact with the travel path S.

[0039] In the latter case where the middle wheel Me is out of contact with the ground, the braking force and the driving force have no effect on the travel path S, which may occur on outdoor walkways, steps, etc., and is one of the important factors that make the 4-wheeled electric wheelchair suitable for outdoor travel.

[0040] Regarding a 4-wheeled electric wheelchair (rear-wheel drive) and a 6-wheeled electric wheelchair having the same wheelbase length Wh and height Hk of the center of gravity G of the wheelchair, Figure 6 (a) to (f) show the ground contact state of the wheels with respect to the convex shape of the running road surface. Figure 6 As shown in (a) and (c), the 6-wheel electric wheelchair can travel with all wheels in contact with the driving road S. Figure 6 As shown in (b) and (d) of FIG. 1 , the front wheel Fe is separated from the ground contact with the traveling path S. As shown in FIG.

[0041] like Figure 6 As shown in (e) and (f), the front wheel Fe that is off the ground and floating in the air shows a sharp pitching behavior (longitudinal swing) relative to the driving road S when the middle wheel Me moving forward Fs crosses the inclined road surface. This pitching behavior does not affect the driving performance, but may cause uneasiness to the seated passenger U. On the driving road, the road surface inclination that switches to a convex shape is more common outdoors, so it is an important factor that makes the four-wheeled electric wheelchair suitable for outdoor driving.

[0042] The advantages and disadvantages of the above-mentioned 4-wheel electric wheelchair (rear-wheel drive) and 6-wheel electric wheelchair are summarized as follows. That is, if the 6-wheel electric wheelchair and the 4-wheel electric wheelchair have the same wheelbase length Wh, the 6-wheel electric wheelchair is more advantageous than the 4-wheel electric wheelchair in terms of ensuring the minimum rotation radius Md in a narrow space and the length dimension from the front end to the rear end of the wheelchair (total length dimension).

[0043] In addition, for downhill and uphill driving roads, the 6-wheeled electric wheelchair has no deviation in the forward tipping limit and the backward tipping limit, so if the 6-wheeled electric wheelchair and the 4-wheeled electric wheelchair have the same wheelbase length Wh, the 6-wheeled electric wheelchair has a higher forward tipping limit and a higher backward tipping limit than the 4-wheeled electric wheelchair. On the other hand, the 6-wheeled electric wheelchair has a disadvantage that the middle wheel Me loses the ground contact on the driving road slope that switches to a concave shape, and the braking force and the driving force do not work.

[0044] In addition, although the six-wheeled electric wheelchair does not affect the driving performance, there is also a problem that the front wheel Fe or the rear wheel Re is separated from the ground on the road surface inclination that switches to a convex shape, causing the wheelchair to sway sharply in the front and rear directions. Therefore, it is desired to introduce a six-wheeled electric wheelchair that eliminates the above problems and disadvantages and has the characteristics of a small minimum rotation radius Md, high turning performance, and space saving that the six-wheeled electric wheelchair originally has.

[0045] As such a 6-wheel electric wheelchair, a 6-wheel electric wheelchair that adopts a rocker-bogie linkage mechanism, which is a conventional passive linkage mechanism, can be considered. It is a 6-wheel electric wheelchair that connects the bogie linkage and the front wheel with a rocker linkage on the basis of connecting the middle wheel on one side with the rear wheel through the bogie linkage, and connects the left and right connecting rods connecting the left and right wheel trains through a differential gear. The characteristics of such a rocker-bogie linkage mechanism are also preferred for a 6-wheel electric wheelchair, but due to the strength and rigidity of the components and the presence of differential gears, there are concerns about the increase in cost and quality when it is adopted in a wheelchair for sale.

[0046] After describing in detail the background situation that serves as the motivation for the present invention, the present invention is described below. The multi-wheeled wheelchair of the present invention proposes and adopts a double rocker arm linkage mechanism as a new passive linkage mechanism. The double rocker arm linkage mechanism connects the front wheel and the middle wheel, and the middle wheel and the rear wheel with a rocker arm linkage, and connects the two rocker arm linkages at the middle wheel position so as to be able to transmit displacement in the up and down directions only. In the rocker arm bogie linkage mechanism, one end of the rocker arm linkage mounted on the vehicle body frame is connected to the central part of the bogie linkage. That is, the three wheels on one side are associated by connecting the rocker arm linkage and the bogie linkage in series. On the other hand, the double rocker arm linkage mechanism of the multi-wheeled wheelchair of the present invention connects the two rocker arm linkages respectively mounted on the vehicle body frame via a linkage connection portion, thereby establishing an association between the three wheels on one side.

[0047] Next, a multi-wheeled wheelchair 10 according to an embodiment of the present invention will be described.

[0048] The following reference Figure 7 to Figure 10 The embodiments of the present invention are described. Figure 7 As shown in the figure, a multi-wheeled wheelchair 10 according to an embodiment of the present invention has a seat 12 mounted on a body frame 11. Front wheels 13, rear wheels 14, and middle wheels 15 arranged between the front wheels 13 and the rear wheels 14 are provided at positions on the left and right sides of the body frame 11 relative to the front of the seat 12, i.e., the front of the multi-wheeled wheelchair 10 in the traveling direction T. Thus, the multi-wheeled wheelchair 10 is a six-wheeled electric wheelchair. In the following figures, for convenience, only one side of the front wheel 13, the rear wheel 14, and the middle wheel 15 is shown in a schematic diagram, not both sides.

[0049] The middle wheel 15 is set to have a larger diameter than both the front wheel 13 and the rear wheel 14 , and the middle wheel 15 is rotationally driven along the travel path St as a driving wheel, so that the front wheel 13 and the rear wheel 14 are driven along the travel path St as driven wheels.

[0050] In the following description, the front wheel 13 and the rear wheel 14 are described as being of equal diameter, but they are not limited to being of equal diameter and may be of different diameters. In addition, the middle wheel 15 as a driving wheel is preferably larger in diameter than the front wheel 13 and the rear wheel 14, but a larger diameter is not essential. Although not shown in the figure, the electric motor 40 is started by operating a joystick provided as an operating lever. While the electric motor 40 is started, the middle wheel 15 is driven as a driving wheel, so that the multi-wheeled wheelchair 10 can be operated to move forward, stop, turn left or right, and rotate left and right. The electric motor 40 is installed on the left and right middle wheels 15, respectively. By adjusting the driving force of the electric motor 40 installed on the left and right middle wheels 15, that is, the rotation speed of the left and right middle wheels 15, the multi-wheeled wheelchair 10 can rotate in the left and right directions and can rotate in place.

[0051] The multi-wheeled wheelchair 10 includes a pair of first links 16, which are first rocker links, connecting the front wheels 13, and second links 17, which are second rocker links, connecting the rear wheels 14. The first links 16, the second links 17, and the link connection portion 18 described later constitute a double rocker link mechanism 21.

[0052] The first link 16 includes a first one end 16b, a first other end 16c, and a first swinging portion 16a. The first one end 16b is swingably mounted on the vehicle body frame 11 via the first swinging portion 16a. The first one end 16b extends toward the axle of the front wheel 13 and is connected to the axle of the front wheel 13. The first other end 16c forms a constant angle with the first one end 16b, extends toward the axle of the rear wheel 14, and is connected to the link connecting portion 18.

[0053] The second link 17 includes a second first end 17b, a second other end 17c, and a second swinging portion 17a. The second link 17 is swingably mounted on the vehicle body frame 11 via the second swinging portion 17a. The second first end 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 17c forms a constant angle with the second first end 17b, extends toward the axle of the front wheel 13, and is connected to the link connecting portion 18.

[0054] The first other end portion 16c and the second other end portion 17c are connected via a link connecting portion 18 that associates the swing displacements of each other within a specific swing angle range. The link connecting portion 18 has a middle wheel shaft supporting portion 18a that axially supports the axle of the middle wheel 15, and the axle of the middle wheel 15 is rotatably connected to the link connecting portion 18. As a result, the front wheel 13, the rear wheel 14, and the middle wheel 15 are displaced in conjunction with each other and can swing in a state of following the unevenness of the travel road St.

[0055] The link connection portion 18 is composed of a roller pin 19 (support portion) connected to the second other end portion 17 c and a support receiving portion 20 connected to the first other end portion 17 b .

[0056] like Fig.10 As shown, the support receiving portion 20 has a pair of receiving surface portions 20a, 20a, and a displacement restraining surface portion 20b connected to the ends of the pair of receiving surface portions 20a, 20a. The receiving surface portions 20a and the displacement restraining surface portions 20b cooperate to define a through hole 30 in the shape of a long hole. The receiving surface portion 20a defines a surface extending linearly in the traveling direction T of the multi-wheeled wheelchair 10.

[0057] When the front wheel 13, the rear wheel 14 and the middle wheel 15 are all in contact with the travel path St, the roller pin 19 is configured to be in contact with any one of the pair of receiving surfaces 20a, 20a and to leave a very small gap relative to the other receiving surface 20a. When any one of the front wheel 13, the rear wheel 14 and the middle wheel 15 passes through the unevenness of the travel path St, the first link 16 and the second link 17 want to swing independently, but the roller pin 19 rotates or slides on the receiving surface 20a, so that the swings of the first link 16 and the second link 17 are linked to each other. That is, the roller pin 19 can move while rotating on the receiving surface 20a of the supporting receiving portion 20, so that the displacements of the first link 16 and the second link 17 can be transmitted to each other along with the swing displacements of the first link 16 and the second link 17. (Refer to Figure 8 , Fig. 9 . )

[0058] For example, Figure 7 Driving status and Figure 8 , Fig. 9 Compared with the running state of the front wheel 13, the rear wheel 14 and the middle wheel 15, the load ratio of the longitudinal load W is the same in each state. That is, the middle wheel 15 can exert a nearly constant driving force without being affected by the unevenness of the running road St.

[0059] The ground load of the middle wheel 15 required for traction can be appropriately determined in consideration of the driving conditions. For example, if the total weight of the wheelchair and the occupant U is W, then a:b:c:d=1:1:1:1 (refer to Figure 7), the longitudinal loads at the first swing part 16a and the second swing part 17a are 1 / 2W, and the longitudinal loads to the front wheel 13 and the rear wheel 14 are 1 / 4W respectively. The longitudinal load to the middle wheel 15 is the sum of the longitudinal load 1 / 4W from the first link 16 and the longitudinal load 1 / 4W from the second link 17, that is, 1 / 2W, which can obtain the ground load of the middle wheel 15 required for traction.

[0060] When the travel path St exceeds the predetermined unevenness, the roller pin 19 contacts the displacement suppression surface 20b. As a result, the swinging fluctuation of the first link 16 and the second link 17 is suppressed. If the vehicle continues to move forward or backward under this condition, the middle wheel 15 will be separated from the travel path St and lose the driving force. That is, the displacement suppression surface 20b plays the role of preventing the vehicle from traveling under adverse conditions.

[0061] When there are bumps and depressions that are continuous with the travel path St, the first link 16 and the second link 17 repeatedly swing in different directions. As a result, the roller pin 19 is intended to move in the direction in which the receiving surface 20a extends while being in contact with any one of the pair of receiving surfaces 20a, 20a. As a result, the behavior of the first link 16 and the second link 17 is stabilized.

[0062] In the present embodiment, the roller pin 19 rotatably connected is exemplified, but a pin structure that slides relative to the support receiving portion 20 may be used. However, in this case, the sliding resistance needs to be sufficiently small.

[0063] [Effects of the Embodiments]

[0064] A double rocker link mechanism 21 is formed by connecting the first link 16 as a first rocker link and the second link 17 as a second rocker link via the link connection portion 18 . The vertical movement of the front wheel 13 is linked to the vertical movement of the rear wheel 14 via the double rocker link mechanism 21 .

[0065] Regarding the definition of up and down in the up and down movement of the front wheel 13 and the rear wheel 14, Figure 7 In this way, a direction perpendicular to the horizontal direction F when the multi-wheeled wheelchair 10 is placed on a horizontal plane is defined as a virtual vertical direction E of the multi-wheeled wheelchair 10 fixed to the multi-wheeled wheelchair 10, and based on the virtual vertical direction E, a case of relatively upward movement relative to the vehicle body frame 11 is defined as upward movement, and similarly, a case of relatively downward movement relative to the vehicle body frame 11 is defined as downward movement. For example, in the case of switching from an uphill inclined surface to a horizontal surface, according to this definition, at the switching portion of the inclined surface, the downward movement of the front wheels 13 and the downward movement of the rear wheels 14 are linked.

[0066] Therefore, in Figure 8On the concave inclined switching path S3 shown, the front wheel 13 and the rear wheel 14 rotate upward according to the inclination angles ω1 and ω2, so even on the concave inclined switching path S3, the driving wheel, that is, the middle wheel 15 is in the ground contact state, which can effectively act on the inclined road braking force and driving force. Figure 8 On the concave inclined switching path S3 shown in FIG. 1 , the ground load of the middle wheel 15 is considered to be Figure 7 Although the horizontal configuration of the brakes changes to some extent, the change in the set load is extremely small, and it can be used as a sufficient ground load for braking and driving.

[0067] In addition, Fig. 9 On the convex inclined switching road S4 shown, the front wheels 13 and the rear wheels 14 rotate downward according to the inclination angles ω3 and ω4, so the front wheels 13 and the rear wheels 14, including the middle wheel 15, are also in a ground contact state, which enables the braking force and driving force on the inclined road to act, and when the multi-wheeled wheelchair 10 travels in the travel direction T, even if the road surface switched in a convex shape is inclined, it is possible to prevent the front wheel 13 from being separated from the ground and causing pitching (longitudinal swinging) behavior. Fig. 9 On the upper convex inclined switching path S4 shown in FIG. 1 , the ground load of the middle wheel 15 is considered to be Figure 7 Although the horizontal configuration of the brakes changes to some extent, the change in the set load is extremely small, and it can be used as a sufficient ground load for braking and driving.

[0068] In this way, the multi-wheeled wheelchair 10 involved in the embodiment of the present invention has the excellent effects that a six-wheeled electric wheelchair originally has, such as a small minimum rotation radius Md, high small turning performance and space saving, and can maintain the front wheels 13, the middle wheels 15 and the rear wheels 14 in a grounded state and travel even in the concave inclined switching path S3 and the convex inclined switching path S4.

[0069] Thus, the advantages of the six-wheeled electric wheelchair can be maintained while the disadvantages can be eliminated, so that the six-wheeled electric wheelchair can also be used outdoors instead of being limited to being suitable for indoor use.

[0070] In this embodiment, the link connecting portion 18 is composed of a rotatable roller pin 19 and a support receiving portion 20 defining a through hole 30, but the present invention is not limited thereto. Other structures may be used as long as the same function is obtained. For example, Fig.11 Shown, also can constitute connecting rod connecting portion 218 by the supporting receiving portion 220 of U-shaped and the roller pin 219 that rotates or slides at the supporting receiving portion of U-shaped. In this case, also can carry out shaft support with the axle of centering wheel 15 of roller pin 219.

[0071] The multi-wheeled wheelchair 10 of this embodiment is a six-wheeled electric wheelchair, but is not limited to an electric type, and may also be a manual type. In addition, as the occupant U, not only a person who needs care, but also a healthy person can effectively use it.

[0072] Industrial Applicability

[0073] The multi-wheeled wheelchair of the present invention can maintain the advantages of the six-wheeled electric wheelchair and eliminate the disadvantages, so that the six-wheeled electric wheelchair can also be used outdoors instead of being limited to indoors, so a safe and practical wheelchair can be provided at a low cost, and the industrial applicability is large. In addition, it stimulates the needs of related aspects focusing on the convenience and usability of the six-wheeled electric wheelchair, and contributes to the revitalization of manufacturing-related industries by activating the circulation in the market.

[0074] Description of Reference Numerals

[0075] 10...multi-wheeled 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 swing portion; 17a...second swing portion; 16b...first first end portion; 16c...first other end portion; 17b...second first end portion; 17c...second other end portion; 18...link connecting portion; 19...roller pin; 20...support receiving portion; 20a...receiving surface portion; 20b...displacement suppression surface portion; 30...through hole.

Claims

1. A multi-wheeled wheelchair comprising a body frame, and front wheels, middle wheels and rear wheels arranged at left and right sides of the body frame, It is characterized in that have: A first rocker link having a first end portion pivotally supporting the axle of the front wheel, a first swing portion swingably connected to the vehicle body frame, and a first other end portion opposed to the first end portion across the first swing portion; a second rocker link having a second first end portion pivotally supporting the axle of the rear wheel, a second swing portion swingably connected to the vehicle body frame, and a second other end portion opposed to the second first end portion across the second swing portion; and a connecting rod connecting portion connected to the first other end portion and the second other end portion, The link connection portion includes a middle wheel shaft support portion that shaft supports an axle of the middle wheel, and the link connection portion is displaced in conjunction with the swinging of the first rocker link and the second rocker link.

2. The multi-wheeled wheelchair according to claim 1, characterized in that: The link connecting portion includes: a supporting portion; and a supporting receiving portion connected to the supporting portion.

3. The multi-wheeled wheelchair according to claim 2, characterized in that: The support receiving portion has a pair of receiving surface portions, The support portion is linked with the swing of the first rocker arm link and the second rocker arm link, and moves along the receiving surface portion.

4. The multi-wheeled wheelchair according to claim 3, characterized in that: The support receiving portion has a displacement suppressing surface portion, both ends of which are connected to both ends of the receiving surface portion. The support portion suppresses displacement of the first rocker arm link and the second rocker arm link by contacting the displacement suppressing surface portion.

5. The multi-wheeled wheelchair according to claim 4, characterized in that: The receiving surface portion and the displacement suppressing surface portion cooperatively define a through hole.

6. The multi-wheeled wheelchair according to claim 1, characterized in that: A driving unit for driving the middle wheel is provided.

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