Wheel chair abstract
A drive assistance device for a hand-driven wheel chair has two
running wheels, said running wheels being adapted to be detachably
mounted to a wheel chair frame and being provided with hand rims
for applying manual force. Each of said running wheels comprises
a drive unit having an electric motor, a power supply and an electronic
control unit associated thereto. Said complete drive unit including
said electric motor, said power supply and said electronic control
unit associated thereto is located in the region of the wheel hub.
Preferably, said drive unit including said electric motor, said
power supply and said electronic control unit associated thereto
is adapted to rotate together with said running wheel.
Wheel chair claims
What is claimed is:
1. A drive assistance device for a hand-driven wheel chair having
two running wheels, said running wheels being adapted to be detachably
mounted to a wheel chair frame and being provided with hand rims
for applying manual force, each of said running wheels comprising
a drive unit having an electric motor, a power supply and an electronic
control unit associated thereto, wherein said complete drive unit
including said electric motor, said power supply and said electronic
control unit associated thereto is located in the region of the
wheel hub, wherein said drive unit including said electric motor,
said power supply and said electronic control unit associated thereto
is adapted to rotate together with said running wheel.
2. The drive assistance device according to claim 1, wherein said
running wheel is provided with a safety switch which is adapted
to switch off said drive unit when said running wheel is detached
from said wheel chair frame.
3. The drive assistance device according to claim 1, wherein said
drive unit includes a first adjusting means for adjusting the degree
of drive assistance.
4. The drive assistance device according to claim 1, wherein said
drive unit includes a second adjusting means for adjusting the characteristics
of an after-running of said drive assistance device.
5. The drive assistance device according to claim 1, wherein said
drive unit includes a torque support.
6. The drive assistance device according to claim 1, wherein said
electric motor has a direct drive without a gear transmission.
7. The drive assistance device according to claim 1, wherein said
drive unit includes a gear transmission.
8. The drive assistance device according to claim 1, wherein said
hand rim is supported by a plurality of mounts, said mounts being
mounted at said running wheel at a portion radially outward of the
region of the wheel hub so that the region of the wheel hub is left
unoccupied and is adapted to encompass the drive nut.
9. The drive assistance device according to claim 7, wherein said
mounts are resiliently supported.
10. The drive assistance device according to claim 8, wherein a
load sensor is provided in the region of at least one of said mounts,
said load sensor being adapted to measure the force applied to said
hand rim, to generate a corresponding measuring signal and to transduce
said measuring signal to said electronic control unit of said drive
unit.
11. The drive assistance device according to claim 1, wherein a
quick exchange plug-in axle is provided to attach said running wheel
to said wheel chair frame.
12. The drive assistance device according to claim 1, wherein said
running wheels are formed identically.
Wheel chair description
The invention relates to a drive assistance device for a hand-driven
wheel chair having two running wheels, such running wheels being
adapted to be detachably mounted to the wheel chair frame and being
provided with hand rims for applying manual force, each of said
running wheels comprising a drive unit having an electric motor
as well as a power supply and an electronic control unit associated
thereto.
Such drive assistance devices for wheel chairs having hand rims
for applying manual power are known in the prior art. They serve
to facilitate the use of the wheel chair over long distances or
on uneven tracks. All these known devices require, however, structural
amendments of the wheel chair frame so that it is troublesome to
retrofit already existing wheel chairs with such known drive assistance
devices. Moreover, transportation of wheel chairs having such known
drive assistance devices, for example in the trunk of an automobile,
is rather difficult since detachment of the running wheels from
the frame requires a substantial effort. Furthermore, care has to
be taken during transport of the wheel chair that elements of the
drive assistance device protruding from the wheels are not damaged.
A still further problem associated with such known drive assistance
devices is that sliding or non-contact transmission of signals between
a rotating wheel and a stationary drive assistance device is required.
It is the object of the invention, to provide an improved drive
assistance device for a hand-driven wheel chair which avoids the
above-mentioned problems.
The object to this solution is given in the claims.
According to the present invention, a drive assistance device as
described above is characterized in that the drive unit of a wheel
is a portion of the wheel and is preferably completely provided
in the region of the wheel hub. Accordingly, the drive assistance
device according to the present invention does not require any structural
amendments of the wheel chair frame. All elements of the drive assistance
device are located at the center of the running wheels, i.e in the
region of the wheel hub.
According to a preferred embodiment of the invention, the drive
unit including the winding of the electric motor, the power supply
and the electronic control unit are adapted to rotate together with
the running wheel. This provides the advantage that sensors which
also rotate together with the wheel can be connected to the drive
unit via fixed cables or wire connections which also rotate together
with the running wheel while, in case the drive unit does not rotate
together with the running wheel, inductive or optoelectronic coupling
elements or coupling elements with sliding contact members between
the sensors and the drive units have to be used. Such elements,
however, require additional mounting space, are likely to be contaminated
and may lead to misfunction of the drive of the drive unit.
In a preferred embodiment of the invention, the drive unit of a
wheel includes a first adjusting means which is adapted to adjust
the degree of drive assistance so that the therapeutic value of
the hand-driven wheel chair for developing the arm and shoulder
muscels is maintained while excessive strain to the arm muscels
and arm joints are avoided.
Moreover, the drive unit of a wheel can also include a second adjusting
means which is adapted to adjust the characteristics of an after-running
of the drive assistance device, i.e. the period of time for which
power is left applied to the wheel after the supply of human power
is stopped, the amount of torque which is left applied during this
period and the slope according to which the torque is reduced during
this period.
Furthermore, the drive unit can have a torque support which supports
the running wheel in relation to the wheel chair frame.
The drive unit includes an electric motor. Depending on the kind
of electric motor, the drive unit optionally can be provided with
a gear transmission.
The hand rim is mounted concentrically to the running wheel. However,
it is advantageous if the hand rim is supported at the running wheel
outside the wheel hub so that the structural elements connecting
the hand rim to the running wheel do not extend to the center portion
of wheel, i.e. the region of the wheel hub. Preferably, a plurality
of mounting means are provided which are equiangularly arranged
and which are mounted to the running wheel at a portion radially
outward of the region of the wheel hub. Due to this arrangement,
the region of the wheel hub is left completely unoccupied so that
it can encompass the drive unit of the device. Moreover, it is thereby
possible to integrate the drive unit in the hub portion of the running
wheel without any protrusion.
According to another preferred embodiment of the invention, the
mounting means can be supported in an elastic and resilient manner
so that it can be achieved that the rotational movement of the hand
rim effected by the manual force applied to the hand rim is the
same as if the hand rim would be supported at the center of the
running wheel.
A load sensor or force sensor can be provided, such sensor being
adapted to measure the force applied to the hand rim and to generate
a corresponding measuring signal and to transduce it to the electronic
control unit of the drive unit. In response to this measuring signal
and depending on the setting of the degree of assistance, a corresponding
drive signal is generated and provided to the electric motor. Preferably,
this load sensor or force sensor is mounted in the region of at
least one mounting means.
Furthermore, it is possible to reduce the speed by braking the
wheel chair by means of the drive assistance device when the wheel
chair is running downhill. If a brake force is applied to the hand
rims, the electric motors reverse their running direction.
Further advantages are obtained if the running wheels are adapted
to be mounted to the wheel chair frame by means of a quick change
plug-in axle. Thereby, a wheel chair cannot only be retrofitted
with the drive assistance device in a simple way but can also be
transported in the trunk of a vehicle quickly and without any problems.
To achieve this, the running wheels are detached from the wheel
chair frame via the quick exchange plug-in axle and the wheel chair
frame is folded. The wheel chair can be assembled after the transport
in an equally easy way. Thereby, it is advantageous if the running
wheels are formed identically. In such case, the user has not to
take care which wheel has to be mounted on the left side and which
wheel has to be mounted on the right side of the wheel chair frame.
Preferably, the running wheels are provided with safety switches
which switch off the drive units when the running wheels are detached
from the wheel chair frame. Any unintended activation of the drive
units according to incorrectly mounted or completely dismounted
running wheels, for instance during the transport of the wheel chair,
is thereby ruled out.
It is obvious for a person skilled in the art that the special
features of the various embodiments described above and below can
be realized in any combination as appropriate.
In the following, the invention is further explained by way of
example in connection with a preferred embodiment of a drive assistance
device according to the present invention, making reference to the
drawings, in which:
FIG. 1 is a plan view of a running wheel of a drive assistance
device;
FIG. 2 a sectional view of the running wheel along line II--II
in FIG. 1; and
FIG. 3 is an enlarged detail view of the hand rim support of the
running wheel shown in FIG. 2.
FIG. 1 shows a running wheel 10 having a tire 11 and a hand rim
12 for manual drive. A drive unit 14 is mounted in the region of
the wheel hub. The hand rim 12 is not supported at the running wheel
10 by being mounted to the wheel hub but by four mounting means
15, 16, 17, 18 which are distributed over its perimeter. A main
switch 13 for switching the drive unit 14 on and off is provided
in the center of the drive unit 14. Furthermore, the drive unit
14 comprises a foil sensor 19 for adjusting the after-running characteristics.
A charging socket 20 for charging an accumulator 21 (FIG. 2) as
a power supply means for the drive unit 14 is provided on the opposite
side of the drive unit 14.
The internal structure of the drive unit 14 is shown in FIG. 2.
An electric motor 22 forms the outer radial part of the drive unit
14. Inside thereof accumulators 21 are provided. The complete running
wheel 10 is adapted to be attached to a wheel chair frame (not shown)
by means of a quick change plug-in axle 23. Lock balls 24 which
are adapted to engage with a sleeve at the wheel chair frame in
order to secure the running wheel 10 to the frame are provided at
one end of the plug-in axle 23. A turning handle 25 by means of
which the lock balls 24 can be pushed inside the plug-in axle 23
in order to unlock the plug-in axle 23 is provided at the outer
side of the running wheel 10. On the inner side of the running wheel
10 there is provided a torque support 26. Operating pins 27 for
a safety switch 28 are provided in the region of the plug-in axle
23, such safety switch 28 ensuring that the drive unit 14 only can
be switched on if the running wheel 10 is properly mounted
The support of the hand rim 12 at the running wheel 10 is shown
in FIG. 3. The hand rim 12 is attached to a plurality of mounting
means. One mounting means 15 is shown in FIG. 3. The mounting means
15 in turn is elastically mounted to a support plate 31 via a rubber
member 29 which support plate 31 is connected to a wheel rim 30
of the running wheel 10. The support of the hand rim 12 in such
elastic and resilient manner provides a rotational movement of the
hand rim 12 upon applying a manual force to the hand rim 12 in the
same way as if the hand rim 12 would be supported at the wheel hub
concentrically to the tire 12. A load sensor or force sensor 12
is also provided at the mounting means 15, such load sensor or force
sensor 32 being adapted to measure the force applied to the hand
rim 12 and to generate and transfer a corresponding measuring signal
along one of the mounting means 33 of the running wheel 10. This
measuring signal serves to control the electric motor 22 which is
also rotating. Depending on the force applied to the hand rim 12
and the degree of assistance adjusted via the sensor 19, the power
electronic control unit of the electric motor 22 is driven correspondingly.
The direction of the force applied to the hand rim also can be detected
by the load sensor or force sensor 32. In correspondence therewith,
the electric motor 22 assists either the moving of the wheel 10
in a forward direction or it brakes this movement. |