EP3782595A1

EP3782595A1 - Wheelchair

Info

Publication number: EP3782595A1
Application number: EP19204968.2A
Authority: EP
Inventors: Han-Wei Tang; Keng-Yu Ko
Original assignee: Li Yuan Transmission Co Ltd
Current assignee: Li Yuan Transmission Co Ltd
Priority date: 2019-08-20
Filing date: 2019-10-23
Publication date: 2021-02-24
Anticipated expiration: 2039-10-23
Also published as: TWI765171B; EP3782595B1; TW202108105A

Abstract

A wheelchair including a main frame (1), two main wheels (2), a caster (32) and an assistive driving system (3) is disclosed. The two main wheels (2) are coaxially mounted to two sides of the main frame (1), respectively. A first reference plane (S1) passes through a center of each of the two main wheels (2). The first reference plane (S1) is parallel to the ground. The assistive driving system (3) includes a slanted bar (31) connected to the caster (32) and the main frame (1). The slanted bar (31) has a force-exerting point (P) with respect to the main frame (1). The force-exerting point (P) is located on the first reference plane (S1). The caster (32) is relatively adjacent to a rear end of the main frame (1) than the force-exerting point (P) is.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an assistive device and, more particularly, to a wheelchair without undesired back tilt.

2. Description of the Related Art

A wheelchair is propelled either by an attendant pushing the wheelchair from the rear, or by the user pushing the push rims (which are outward of the main wheels) by hand.
FIG. 1 shows a conventional wheelchair 9 that is designed to reduce the effort of the user pushing the wheels. The wheelchair 9 includes two main wheels 91 and an assistive driving system 92. The two main wheels 91 are coaxial with each other such that a central axis L passes through the centers of the main wheels 91. An axle is connected between the centers of the main wheels 91. The assistive driving system 92 includes a caster arm 921 connected to the axle, as well as a caster 922 connected to the caster arm 921. The caster 922 is on the ground. The rotation of the two main wheels 91 causes the caster 922 to roll, such that the caster 922 assists in the movement of the wheelchair 9. An example of such a wheelchair 9 is disclosed in U.S. Patent No. 10,265,228 .
When the wheelchair 9 is propelled uphill, the resultant center of gravity of the wheelchair 9 and the user is at the back of the wheelchair 9, such that the force generated by the assistive driving system 92 is exerted on the central axis L through the caster arm 921. In this situation, the wheelchair 9 cannot produce a torque that keeps the wheelchair 9 from tilting backwards. As a result, when the wheelchair 9 is propelled uphill, the wheelchair 9 is liable to overturn, raising the safety concern.
In light of this, it is necessary to improve the conventional wheelchair.

SUMMARY OF THE INVENTION

It is therefore the objective of this invention to provide a wheelchair without undesired back tilt as it employs an assistive driving system to generate a torque that keeps the wheelchair from tilting backwards.
It is another objective of this invention to provide a wheelchair whose assistive driving system can be mounted on the conventional wheelchair structure without the use of an additional connection rod.
It is a further objective of this invention to provide a wheelchair without undesired back tilt whose assistive driving system is not excessively protrusive at the back of the wheelchair to avoid accidentally kicking the assistive driving system.
In an aspect, a wheelchair including a main frame, two main wheels, a caster and an assistive driving system is disclosed. The two main wheels are coaxially mounted to two sides of the main frame, respectively. A first reference plane passes through a center of each of the two main wheels. The first reference plane is parallel to the ground. The assistive driving system includes a slanted bar connected to the caster and the main frame. The slanted bar has a force-exerting point with respect to the main frame. The force-exerting point is located on the first reference plane. The caster is relatively adjacent to a rear end of the main frame than the force-exerting point is.
Accordingly, through the arrangement that the force-exerting point of the assistive driving system with respect to the main frame is located on the first reference plane that passes through the centers of the two main wheels, the assistive driving system can be used to support the main frame of the wheelchair. In this regard, the assistive driving system produces a torque that keeps the main frame from tilting backwards about the centers of the two main wheels. Thus, when the wheelchair is propelled uphill, the wheelchair will not tilt backwards or even turnover, improving the safety in use.
In a form shown, the main frame includes a left side frame, a right side frame, and a folding mechanism connected between the left and right side frames. The slanted bar of the assistive driving system is connected to the folding mechanism. This not only attains convenient assembly but also permits the assistive driving system to be mounted on the conventional wheelchair structure. Thus, additional cost will not incur and the weight of the wheelchair will not increase.
In the form shown, the folding mechanism includes a cross frame in a form of two cross bars. A first one of the two cross bars has a first end fixed to the left side frame and a second end fixed to the right side frame. A second one of the two cross bars has a first end fixed to the right side frame and a second end fixed to the left side frame. The slanted bar is connected to a crossing point of the two cross bars. Through the simple structure, the main frame can have a foldable structure and permits the installation of the assistive driving system, thereby reducing the cost and improving the efficiency in assembly.
In the form shown, a second reference plane passes through the centers of the two main wheels. The second reference plane is orthogonal to the first reference plane. The force-exerting point is located at a side of the second reference plane relatively adjacent to a front end of the main frame opposite to the rear end of the main frame. Thus, the caster would not be excessively protrusive at the rear end of the main frame to reduce the likelihood of the attendant accidentally kicking the caster, improving the convenience in use.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 shows the main wheels of a conventional wheelchair that are coupled with an assistive driving system.
FIG. 2 is an unassembled, perspective view of a wheelchair according to a preferred embodiment of the invention.
FIG. 3 is a side view of the wheelchair of FIG. 2.
FIG. 4 shows the main wheels of the wheelchair of the invention that are coupled with an assistive driving system.

In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms "first", "second", "third", "fourth", "inner", "outer", "top", "bottom", "front", "rear", "axial", "radial", "longitudinal", "transverse", "length", "width", "height" and similar terms are used hereinafter, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings, and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 shows a wheelchair without undesired back tilt according to an embodiment of the invention. The wheelchair includes a main frame 1, two main wheels 2 and an assistive driving system 3. The two main wheels 2 and the assistive driving system 3 are connected to the main frame 1.
The main frame 1 can have any shape as long as it can stably support other components of the wheelchair for assembly purpose. In this embodiment, the main frame 1 includes a left side frame 11, a right side frame 12 and a folding mechanism 13. The folding mechanism 13 is located between the left side frame 11 and the right side frame 12. The folding mechanism 13 can be directly connected to or indirectly coupled with the left side frame 11 and the right side frame 12. The folding mechanism 13 can have an unfolding state or a folding state. In the unfolding state, the left side frame 11 and the right side frame 12 are spaced from each other to form a sufficient space for the user. In the folding state, the left side frame 11 and the right side frame 12 are spaced from each other at a small distance to reduce the space required for storage of the wheelchair. In a non-limiting example, the folding mechanism 13 includes a cross frame in the form of two cross bars 131. A first one of the two cross bars 131 has a first end fixed to the left side frame 11 and a second end fixed to the right side frame 12. A second one of the two cross bars 131 has a first end fixed to the right side frame 12 and a second end fixed to the left side frame 11. The two cross bars 131 are pivotally connected to each other at the crossing point.
Referring to FIGS. 2 and 3, the two main wheels 2 are located at two sides of the main frame 1 and are coaxially connected to the main frame 1. In other words, the two main wheels 2 are located at two sides of the main frame 1 respectively outward of the left side frame 11 and the right side frame 12. The main wheels 2 are rotatably fixed to the left side frame 11 and the right side frame 12, respectively, with a central axis L passing through the centers of the two main wheels 2. When the wheelchair is placed on a horizontal plane, a first reference plane S1 passes through the centers of the two main wheels 2, and a second reference plane S2 passes through the centers of the two main wheels 2. The first reference plane S1 and the second reference plane S2 are orthogonal to each other.
The assistive driving system 3 includes a slanted bar 31 and a caster 32. The slanted bar 31 can be directly connected to or indirectly coupled with the caster 32 and the main frame 1. In this regard, the slanted bar 31 has a force-exerting point P with respect to the main frame 1. The force-exerting point P is located on the first reference plane S1. Preferably, the force-exerting point P is located on the left side of the second reference plane S2 while located on the first reference plane S1. The caster 32 remains in contact with the ground and is more adjacent to the rear end of the main frame 1 than the force-exerting point P is.
In a non-limiting example, since the crossing point (the pivotal point) of the two cross bars 131 of the folding mechanism 13 is located on the first reference plane S1 and is at the left side of the second reference plane S2, the slanted bar 31 can be connected to the crossing point of the two cross bars 131. This not only attains convenient assembly but also avoids the use of an additional component (a connecting rod) as the invention can be carried out on the conventional wheelchair structure. Advantageously, additional costs will not incur and the weight of the wheelchair will not increase. Furthermore, the interior of the caster 32 can be installed with a driving means (not shown) such as a hub motor. In this case, when the two main wheels 2 rotate, the driving means can provide power to rotate the caster 32, thereby facilitating the movement of the wheelchair.
Referring to FIGS. 3 and 4, based on the above structure, when the wheelchair according to the invention is propelled uphill, the resultant center of gravity of the wheelchair and the user is at the back of the wheelchair. In this regard, as the caster 32 of the assistive driving system 3 rotates to propel the wheelchair, the caster 32 produces a force that is transmitted to the force-exerting point P through the slanted bar 31 to support the main frame 1. The force is a torque that keeps the main frame 1 from tilting backwards about the central axis L. Thus, when the wheelchair according to the invention is propelled uphill, the wheelchair would not tilt backwards or even turnover. It is even safer to use the wheelchair when the road surface is flat.
It is noted that the slanted bar 31 can always produce a torque that keeps the main frame 1 from tilting backwards as long as the force-exerting point P of the slanted bar 31 with respect to the main frame 1 is located on the first reference plane S1. However, when the force-exerting point P of the slanted bar 31 is at the right side of the second reference plane S2, the caster 32 would be excessively protrusive at the back side of the main frame 1. As a result, the attendant who pushes the wheelchair might accidentally kick the caster 32, causing inconvenience in use. Thus, when the force-exerting point P of the slanted bar 31 is located at the left side of the second reference plane S2, it not only prevents the back tilt of the wheelchair but also avoids accidentally kicking the caster 32.
In another embodiment where the main frame 1 does not include the folding mechanism 13, the slanted bar 31 of the assistive driving system 3 can be connected to other part of the main frame 1 as long as the force-exerting point P of the slanted bar 31 is located at the first reference plane S1.
In summary, through the arrangement that the force-exerting point of the assistive driving system with respect to the main frame is located on the first reference plane that passes through the centers of the two main wheels, the assistive driving system can be used to support the main frame of the wheelchair. In this regard, the assistive driving system produces a torque that keeps the main frame from tilting backwards about the centers of the two main wheels. Thus, when the wheelchair is propelled uphill, the wheelchair will not tilt backwards or even turnover, improving the safety in use.

Claims

A wheelchair comprising:
a main frame (1);

two main wheels (2) coaxially mounted to two sides of the main frame (1), respectively, wherein a first reference plane (S1) passes through a center of each of the two main wheels (2), and wherein the first reference plane (S1) is parallel to ground; and

a caster (32),

wherein the wheelchair is characterized in further comprising:
an assistive driving system (3) including a slanted bar (31) connected to the caster (32) and the main frame (1), wherein the slanted bar (31) has a force-exerting point (P) with respect to the main frame (1), wherein the force-exerting point (P) is located on the first reference plane (S1), and wherein the caster (32) is relatively adjacent to a rear end of the main frame (1) than the force-exerting point (P) is.
The wheelchair as claimed in claim 1, characterized in that the main frame (1) includes a left side frame (11), a right side frame (12), and a folding mechanism (13) connected between the left and right side frames (11, 12), wherein the slanted bar (31) of the assistive driving system (3) is connected to the folding mechanism (13).
The wheelchair as claimed in claim 1, characterized in that the folding mechanism (13) includes a cross frame in a form of two cross bars (131), wherein a first one of the two cross bars (131) has a first end fixed to the left side frame (11) and a second end fixed to the right side frame (12), wherein a second one of the two cross bars (131) has a first end fixed to the right side frame (12) and a second end fixed to the left side frame (11), and wherein the slanted bar (31) is connected to a crossing point of the two cross bars (131).
The wheelchair as claimed in claim 1, characterized in that a second reference plane (S2) passes through the centers of the two main wheels (2), wherein the second reference plane (S2) is orthogonal to the first reference plane (S1), and wherein the force-exerting point (P) is located at a side of the second reference plane (S2) relatively adjacent to a front end of the main frame (1) opposite to the rear end of the main frame (1).