JP2004097273A - Vertically moving device for electric wheelchair - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertically moving device for an electric wheelchair which is light-weight and compact, and in addition, does not apply a feeling of incongruity by providing an approximately even lifting force at the time of lifting. <P>SOLUTION: The electric wheelchair is equipped with this vertically moving device 6 which is provided between a seat cushion 21 and the electric wheelchair body 2, and vertically moves the seat cushion 21 by an X link body 63. In this electric wheelchair, a screw spindle 64 which extends in the direction of a guide hole 62a on a link 63b of the X link body 63, a nut 65 which is screwed with the screw spindle 64 and freely turnably supports a slider 68b which slides in the guide hole 62a, a drive motor 66 which rotates the screw spindle 64 in the peripheral direction, and a coil spring 67 which is located between the seat cushion 21 and the electric wheelchair body 2 and urges the seat cushion 21 upward are provided. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of lifting devices for electric wheelchairs.
[0002]
[Prior art]
In recent years, a vehicle that can be driven while a wheelchair user is on an electric wheelchair has been known (for example, see Non-Patent Document 1). This vehicle is provided with a ramp for getting on and off at the side opening of the vehicle, and a wheelchair user can get on and off without assistance.
[0003]
Normally, if you ride an electric wheelchair in a vehicle, the position of the wheelchair user's head may become too high, which may hinder driving, so it is necessary to adjust the height of the seat cushion, that is, the seating surface on the wheelchair side. There is.
[0004]
Conventionally, as an electric wheelchair provided with a height adjusting function, there is one using a support and a ball screw (for example, refer to Patent Document 1).
[0005]
On the other hand, some non-electric wheelchairs are provided with an elevating mechanism using an X link and a handle for expanding and contracting the link (see, for example, Patent Document 2).
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-190601 (2-4 pages, FIG. 1)
[Patent Document 2]
JP 2001-346832 A (page 4, FIG. 5)
[Non-Patent Document 1]
JOY-VAN National Caravan “Research on New Support System for Local Life”, [September 2, 2002 search] Internet [0007]
[Problems to be solved by the invention]
However, the former using the column and the ball screw among the above-mentioned prior arts is unsuitable as an electric wheelchair of a type that gets into a vehicle because the apparatus is increased in size and weight.
[0008]
On the other hand, in the latter case using the X-link, the seat must be adjusted manually by turning the handle, and the wheelchair is not electrically operated, so that it is difficult to use without an assistant.
[0009]
The present invention has been made paying attention to the above problems, and its object is to provide a lifting device for an electric wheelchair that is lightweight and compact, and that does not give a sense of incongruity when a substantially constant lifting force is obtained during lifting. There is to do.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the electric wheelchair lifting apparatus according to claim 1 of the present invention is provided between the seat cushion and the electric wheelchair main body, and lifts and lowers the seat cushion by the X-link mechanism. The screw shaft extending in the horizontal direction along one guide groove of the X link mechanism, and a nut that is rotatably engaged with the screw shaft and that slides on the guide groove and rotatably supports the link movable end. And a drive motor that rotates the screw shaft in the circumferential direction, and a coil spring that is positioned between the seat cushion and the electric wheelchair body and biases the seat cushion upward.
[0011]
According to a second aspect of the present invention, in the lifting device for an electric wheelchair according to the first aspect, the total lift force acting on the seat cushion by the drive motor and the coil spring at the seat cushion lower limit position, and the seat cushion upper limit position. The spring characteristics of the coil spring are set so that the total lift force is the same.
[0012]
【The invention's effect】
In the lifting device for an electric wheelchair according to claim 1, when the screw shaft is rotated by the drive motor from the state in which the X link is reduced and the seat cushion is in the lower limit position, the guide is guided to the nut screwed with the screw shaft. Thrust works in the direction of the groove. The vertical upward component of this thrust and the reaction force of the coil spring become the lift force that raises the seat cushion.
[0013]
Here, the vertical upper component M acting on the X link from the drive motor is expressed by the following equation, where η is the efficiency of the X link, P is the thrust of the nut by the drive motor, and θ is the angle between the screw shaft and the X link. expressed.
M = η × P × tan θ
Therefore, the lift force by the X link has a characteristic that the smaller the seat cushion is closer to the lower limit position (the smaller θ is), the smaller the lift force is, and the larger the X link is extended and the seat cushion approaches the upper limit position (the larger θ is). ing.
[0014]
On the other hand, the reaction force S of the coil spring is expressed by the following equation, where k is the spring constant and δ is the deflection of the coil spring.
S = k × δ
Therefore, the lift force by the coil spring has a characteristic that it becomes larger as the seat cushion is closer to the lower limit position (as δ is larger) and becomes smaller as the seat cushion is closer to the upper limit position (when δ is smaller).
[0015]
That is, in the present invention, the seat cushion is lifted and lowered by combining the mechanisms having the opposite lift characteristics of the X link and the coil spring driven by the motor, so that it is compared with the lifting device using only the X link driven by the motor. Thus, the variation in lift force can be kept small, and the wheelchair user does not feel uncomfortable.
[0016]
In addition, since the screw shaft extends horizontally along one guide groove of the X-link mechanism, it takes up less space and is compact compared to the conventional technology in which the pillars and ball screws are arranged vertically. And weight reduction can be achieved.
[0017]
In the lifting device for an electric wheelchair according to claim 2, since the total lift force is set to be the same at the seat cushion lower limit position and the upper limit position, as shown in the characteristic diagram of FIG. The total lift force can be kept almost constant over the entire range.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a side view showing an electric wheelchair to which the lifting device of the present invention is applied.
In the figure, the electric wheelchair 1 is mainly composed of 2 electric wheelchair bodies, 3 drive wheels, 4 casters, 5 footrests, and 6 lifting devices.
[0019]
The electric wheelchair body 2 includes a seat cushion 21, a seat back 22, an armrest 23, a wheelchair operation unit 24, and a seat lifting / lowering operation unit 25.
[0020]
The electric wheelchair 1 constitutes a part where a person sits by a seat cushion 21, a seat back 22, an armrest 23, and a footrest 5, and driving wheels 3 driven by a driving device (not shown) are provided on the left and right sides of the rear part. The driving device for the driving wheel 3 is braked so that the driving wheel 3 is not free when stopped. Further, casters 4 having a diameter smaller than that of the drive wheels 3 are provided on the left and right of the front portion of the electric wheelchair 1.
[0021]
Next, the structure of the lifting device 6 will be described.
FIG. 2 is a side view showing the structure of the lifting device 6. The lifting device 6 includes a lower frame 61, an upper frame 62, an X link body 63, a screw shaft 64, a nut 65, a drive motor 66, and a coil spring 67. It is configured.
[0022]
The lower frame 61 is fixed to the upper portion of the lifting device body 2, and a guide hole 61 a long in the front-rear direction of the wheelchair body 2 is formed on the left and right front sides thereof.
[0023]
The upper frame 62 is fixed to the lower part of the seat cushion 21, and a guide hole 62a longer than the guide hole 61a is formed on the left and right front sides thereof.
[0024]
The X link body 63 is provided on the left and right sides of the wheelchair body 2 and is composed of two links 63a and 63b that are connected to each other so as to be relatively rotatable at the center. The upper end of the link 63a is pivotally supported by the upper frame 62, and the other end is rotatably connected to a slider 68a provided in the guide hole 61a so as to be slidable in the front-rear direction.
[0025]
The upper end of the link 63b is rotatably connected to a slider 68b provided in the guide hole 62a so as to be slidable in the front-rear direction, and the other end is pivotally supported by the lower frame 61.
[0026]
The screw shaft 64 is provided in the horizontal direction along the direction of the guide hole 62a. The screw shaft 64 is rotated by a drive motor 66 driven by a battery (not shown) to move the nut 65 in the axial direction of the screw shaft 64. The nut 65 is rotatably supported by the slider 68b.
[0027]
The coil spring 67 is provided between the lower frame 61 and the upper frame 62 and urges the upper frame 62 upward.
[0028]
Next, the operation will be described.
2, when the drive motor 66 is not driven, only the reaction force S of the coil spring 67 acts on the seat cushion 21 as a lift force that raises the seat cushion 21. Yes.
[0029]
When the drive motor 66 is driven to rotate the screw shaft 64, the nut 65 moves rearward (right side in the figure). At this time, when the thrust of the nut 65 is P, the vertical upper component M of the thrust P is expressed by the following expression (1).
M = η × P × tan θ. . . (1)
In addition, η is the efficiency of the X link body 63, and θ is an angle formed by the screw shaft 64 and the link 63b.
[0030]
If the reaction force of the coil spring 67 is S, the reaction force S is expressed by the following equation (2).
S = k × δ. . . (2)
Here, k is a spring constant and δ is a deflection.
[0031]
Therefore, when the seat cushion 21 is at the lower limit position, θ is small and δ is large, so the vertical upward component M of the thrust P is small, and on the contrary, the reaction force S of the coil spring 67 is large.
[0032]
FIG. 3 is a side view of the lifting device showing a state in which the seat cushion 21 is at the upper limit position. At this time, since θ is large and δ is small, the vertical upper component M of the thrust P is large, and conversely, the coil spring 67. The reaction force of becomes smaller.
[0033]
Here, the characteristics of the lift force by the lifting device 6 will be described with reference to FIG.
As described above, the vertical upward component M of the thrust P that changes depending on the angle θ is represented by a quadratic curve that is minimum at the seat lower limit position and maximum at the seat upper limit position. On the other hand, the reaction force S of the coil spring 67 is expressed by a linear function that is maximum at the seat lower limit position and minimum at the seat upper limit position. As shown in the figure, the spring characteristics of the coil spring 67 are set so that the total lift force at the seat lower limit position is the same as the total lift force at the seat upper limit position. Accordingly, the total lift amount obtained by combining the vertical upper component M and the reaction force S is substantially constant from the sheet lower limit position to the sheet upper limit position.
[0034]
Next, the effect will be described.
In the electric wheelchair according to the present embodiment, since the elevating device 6 is configured using the X link body 63 and the coil spring 67 that are expanded and contracted by the drive motor 66 having the opposite lift characteristics, the total lift force is substantially constant. Thus, the wheelchair user does not feel uncomfortable when the seat cushion 21 is raised and lowered.
[0035]
In addition, since the screw shaft 64 extends in the horizontal direction along the direction of the guide hole 62a, it takes up less space than the conventional technique in which the support and the ball screw are arranged in the vertical direction. Weight reduction can be achieved.
[0036]
Although the embodiment of the present invention has been described above, the specific configuration of the present invention is not limited to the present embodiment, and even if there is a design change or the like without departing from the gist of the invention, Included in the invention.
[0037]
For example, in the present embodiment, an example is shown in which one guide hole for sliding the link of the X link mechanism is provided in each of the upper frame and the lower frame, but two guide holes are provided in one of the upper or lower frame. It is good also as the provided structure.
[Brief description of the drawings]
FIG. 1 is a side view of an electric wheelchair according to an embodiment.
FIG. 2 is a side view of the lifting device.
FIG. 3 is a side view of the lifting device showing a state in which the seat cushion is in an upper limit position.
FIG. 4 is a characteristic diagram showing lift force of the lifting device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electric wheelchair 2 Electric wheelchair main body 21 Seat cushion 22 Seat back 23 Armrest 24 Wheelchair operation part 25 Seat raising / lowering operation part 3 Drive wheel 4 Caster 5 Footrest 6 Lifting apparatus 61 Lower frame 61a Guide hole 62 Upper frame 62a Guide hole 63 X link body 63a link 63b link 64 screw shaft 65 nut 66 drive motor 67 coil spring 68a slider 68b slider

Claims (2)

In the lifting device for an electric wheelchair that is provided between the seat cushion and the electric wheelchair body and raises and lowers the seat cushion by an X link mechanism,
A screw shaft extending horizontally along one guide groove of the X link mechanism;
A nut that is threadably engaged with the screw shaft and rotatably supports a link movable end that slides in the guide groove;
A drive motor for rotating the screw shaft in the circumferential direction;
A coil spring located between the seat cushion and the electric wheelchair body, and biasing the seat cushion upward;
A lifting device for an electric wheelchair characterized by comprising: The lifting device for an electric wheelchair according to claim 1,
The spring characteristic of the coil spring is set so that the total lift force acting on the seat cushion by the drive motor and the coil spring at the seat cushion lower limit position is the same as the total lift force at the seat cushion upper limit position. Electric wheelchair lifting device.

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