Wheel chair abstract
A driving gear for a muscle power driven vehicle, such as a wheel
chair, comprising an input shaft drivable by means of a lever, and
adapted to be coupled through at least two freewheel clutches to
an output shaft arranged to be connected to a wheel hub of the vehicle,
wherein the driving gear (4) is housed in a closed housing (11,
12) which is arranged to be coupled through said output shaft (22)
to the wheel hub (5) of the vehicle, said input shaft (7) being
fixedly coupled to an input gear wheel (14) meshing with two separate
intermediate gear wheels (16, 16') adapted to be connected through
freewheel clutches operative in opposite directions of rotation
to one (20) or the other (20') of two meshing change gear wheels,
one of which also meshes with a first output gear wheel (21) mounted
on the output shaft.
Wheel chair claims
I claim:
1. In a driving gear for a muscle power driven vehicle comprising
an input shaft drivable by means of a lever, and adapted to be coupled
through at least two freewheel clutches to an output shaft arranged
to be connected to a wheel hub of the vehicle, the improvement which
comprises that the driving gear is housed in a closed housing which
is arranged to be coupled through said output shaft to the wheel
hub of the vehicle, said input shaft being fixedly coupled to an
input gear wheel meshing with two separate intermediate equally
sized gear wheels adapted to be connected through freewheel clutches
operative in opposite directions of rotation to one or the other
of two meshing equally sized change gear wheels, one of which also
meshes with a first output gear wheel mounted on the output shaft.
2. A driving gear according to claim 1, wherein a second output
gear wheel is present on said output shaft, which gear wheel is
in mesh with the second change gear wheel.
3. A driving gear according to claim 1, wherein the output gear
wheels can each be coupled with the output shaft by means of a row
of balls, which balls can be displaced outwards by means of an axially
slidable engaging shaft mounted within the output shaft and including
a shifting boss.
4. A driving gear according to claim 3, wherein the engaging shaft
is connected at one end to a tension spring and at the opposite
end to a shifting chain operable by means of a pawl provided on
said drive lever.
5. A driving gear as claimed in claim 1, wherein the output shaft
is arranged to be coupled with the wheel hub by means of a keyed
connection.
6. A driving gear as claimed in claim 1, wherein a brake shoe is
provided on the wall of the drive gear housing which faces the hub,
which brake shoe can be pressed against a wall of the hub by means
of an operating rod projecting from the housing.
Wheel chair description
This invention relates to a driving gear for a muscle power driven
vehicle, such as a wheel chair, comprising an input shaft drivable
by means of a lever, and adapted to be coupled through at least
two freewheel clutches to an output shaft arranged to be connected
to a wheel hub of the vehicle.
A driving gear of this kind is known from European patent application
0,136,705. This known gear is built in as to a considerable part
in the hub of a wheel chair wheel, and includes two input shafts,
each provided with a rope pulley. These rope pulleys can be driven
by means of a lever, carrying two other rope pulleys at its lower
end. One pair of rope pulleys, one pulley of which is connected
to the lever and the other to the wheel hub, serves to drive the
wheel hub during the push stroke of the lever, while the other pair
of rope pulleys serves to drive the wheel hub during the pull stroke
of the lever. Indeed, the V-rope is lapped cross-wise around the
second pair of rope pulleys to provide the desired reversal of movement
in the drive system.
The two rope pulleys associated with the wheel hub can be connected
through freewheel clutches operative in the same direction of rotation
with a drive bush provided within the wheel hub, which drive bush
is connected through a gear clutch with the wheel hub proper.
For driving the wheel chair in the rearward direction, a third
freewheel clutch is provided, which is operative in the other direction
of rotation from the two former freewheel clutches, and can be coupled
to the wheel hub through one of the rope pulleys connected to the
wheel hub by shifting the gear clutch into the reverse position.
A disadvantage of this known clutch is the sub-division of the
drive gear, which is arranged partly within the wheel hub and partly
at the lower end of the lever, with both parts of the gear being
coupled together by means of rope pulleys. The presence of non-screened
V-ropes in a wheel chair is objectionable on the ground of both
safety and efficiency considerations. As a considerable part of
the drive gear is mounted within the wheel hub, the gear is unsuitable
for being mounted as a separate drive unit in wheel chairs with
the normal, conventional wheel hubs.
To drive the wheel chair in the reverse direction, the pulling
movement of the lever is available only, and its pushing movement
is a dead stroke. For the wheel chair to be driven in the rearward
direction also during the pushing stroke, an additional freewheel
clutch should be included in the drive gear.
It is an object of the present invention to overcome the above-described
disadvantages of this known driving gear. For this purpose, the
driving gear according to the invention is characterized by being
housed in a closed housing which is arranged to be coupled through
said output shaft to the wheel hub of the vehicle, said input shaft
being fixedly coupled to an input gear wheel meshing with two separate
intermediate gear wheels adapted to be connected through freewheel
clutches operative in opposite directions of rotation to one or
the other of two meshing change gear wheels, one of which also meshes
with a first output gear wheel mounted on the output shaft.
By virtue of the entire drive gear being housed in a closed housing,
which can be coupled in a relatively simple manner with the hub
of a wheel chair wheel, the driving gear can be more easily adapted
to, for example, the transmission ratio desirable for a given wheel
chair. By connecting the freewheel clutches present in series, one
and the same output gear wheel can be driven in the same direction
during both the push stroke and the pull stroke of the lever, whereby,
for example, during the push stroke the drive is effected through
one change gear wheel, and during the pull stroke automatically
the other change gear wheel is engaged. There is thus in addition
obtained one single input shaft which can be driven directly, i.e.
without a rope transmission, through the lever.
To drive the wheel chair in the rearward direction, a second output
gear wheel is provided on the output shaft, which gear wheel meshes
with the second change gear wheel.
By providing a separate output gear wheel on the output shaft for
the movement in the rearward direction, the movement in the rearward
direction can take place during both the pushing and the pulling
stroke of the lever. During these movements, the change gear wheels
perform exactly the same function as during the movement in the
forward direction.
For the drive of the wheel chair in one or in the other direction,
the output gear wheels can each be coupled with the output shaft
by means of a row of balls, which balls can be displaced outwards
by means of an axially slidable engaging shaft mounted within the
output shaft and including a shifting boss.
By shifting the engaging shaft, the row of balls associated with
one output gear wheel can be engaged, and the row of balls for the
other output gear wheel remains inoperative, or the other way round.
The engaging shaft can also be placed in a neutral position, in
which neither of the rows of balls arranged within the output gear
wheels is coupled with the associated output gear wheel.
One embodiment of the driving gear according to the present invention
will now be described in more detail, by way of example, with reference
to the accompanying drawings. In said drawings,
FIG. 1 shows a side-elevational view of a wheel chair according
to the present invention;
FIG. 2 is a partial rear view of the wheel chair shown in FIG.
1:
FIG. 3 shows a cross-sectional view of the driving gear, coupled
with the wheel hub of a wheel chair wheel;
FIG. 4 is a cross-sectional view, taken on the line IV--IV of FIG.
3; and
FIG. 5 shows a cross-sectional view, taken on the line V--V of
FIG. 4.
The wheel chair 1 shown in FIGS. 1-2 includes two relatively large
rear wheels 2 and two smaller, swivelling front wheels 3. The hub
5 of the rear wheels is connected to a drive gear 4, including an
input shaft 7 which can be driven by means of an operating lever
6. Lever 6 also serves for steering the two front wheels 3 through
bottom ropes not shown. Disposed at the upper end of the operating
lever 6 is a change pawl 8 for shifting the engaging shaft of the
driving gear into, for example, the forward, rearward or neutral
position.
The driving gear 4 is illustrated in FIGS. 3-5. Gear 4 is housed
in a housing consisting of two dish-shaped housing sections 11,
12, which are bolted together. Housing section 12 is connected in
a manner to be described hereinafter with the wheel hub 5 of a rear
wheel 2.
The input shaft 7 of the driving gear is at the bottom of housing
11, 12 and is journalled in bearings 13. Mounted on input shaft
7 is an input gear wheel 14. The entire driving gear can run in
an oil bath, which can be drained by means of a plug 15 provided
at the bottom of the housing. The lower end of operating lever 6
is coupled in a suitable manner to the part of the input shaft 7
projecting from housing 11, 12, for example, by means of a crank
key.
The input gear wheel 14 meshes with two intermediate gear wheels
16, 16' respectively mounted on sub-shafts 17, 17'. These sub-shafts
are journalled in the two housing halves by means of bearings 18.
Mounted on the intermediate shaft 17, through a one-way freewheel
clutch 19, is a change gear wheel 20 which meshes with gear wheel
21 mounted on output shaft 22.
Similarly, a change gear wheel 20' is mounted on intermediate shaft
17' (see FIG. 4) through a freewheel clutch 19', whose direction
of engagement is opposite to the direction of engagement of clutch
19. Change gear wheel 20' meshes with both change gear wheel 20
and a gear wheel 21' mounted on output shaft 22. Gear wheel 21 on
output shaft 22 serves to drive the wheel chair in the forward direction,
whereas gear wheel 21' on output shaft 22 serves to drive the wheel
chair in the rearward direction.
Output shaft 22 is journalled in housing 11, 12 by means of bearings
29. Output shaft 22 is hollow, and within it an engaging shaft 24
is slidably mounted. Shaft 24 includes a shifting boss which is
capable of forcing one of the two rows of balls 23 provided in output
shaft 22 in the outward direction, thereby to effect a coupling
with one of the output gear wheels 21, 21'. Engaging shaft 24 is
provided at the left-hand end with a tension spring 25, while a
shifting chain 26 is connected to the other end of shaft 24. Mounted
on the right-hand housing half 11, is a chain guide 27, by means
of a bolt 28, in order that chain 25 may be kept in the correct
position. The position of the shifting boss on shaft 24 is controlled
by pawl 8 on operating lever 6, which pawl can pull the chain 26
outwardly to a greater or lesser extent against the action of spring
25. In the position shown in FIG. 3, the output gear wheel 21 is
engaged as the boss on the shaft 24 has pushed the row of balls
24 outwardly against the central hole in gear wheel 21.
Driving gear 4 is connected to wheel hub 5 through the wheel axle
22, the end of which is received in a hub bushing 30, which by means
of a key 32 is rotationally connected to the output shaft 22. Bushing
30 is axially pressed against a raised edge of wheel axle 22 by
means of a bolt 31. Bushing 30 is connected to wheel hub 5 so as
to be restrained from axial and circumferential movements. Within
the wheel hub, a brake shoe is provided on a brake shaft 33 screwed
into the wall of housing section 12. The other end of the brake
shoe is connected to an actuating cam 35 journalled for rotation
in a bushing 36 mounted in the wall of housing section 12. Cam 35
is rotatable by means of a brake rod 34, which projects from the
top of housing 11, 12. The opening in the top wall of the housing
is covered by means of a ring 37 and a bellows 38 connected with
it.
The driving gear operates as follows:
With the engaging shaft 24 in the position as shown in FIG. 3,
in which the output gear wheel 21 is coupled with output shaft 22,
a forwardly directed pushing stroke of actuating lever 6 will drive
the input shaft 7 counter-clockwise in FIG. 4. Accordingly, the
intermediate gear wheel 16 mounted on the intermediate shaft 17
turns clockwise, when freewheel clutch 19 is operative and consequently
drives gear wheel 20 clockwise. Gear wheel 20 is coupled with the
output gear wheel 21, which accordingly is driven counter-clockwise,
and hence wheel hub 5 is also driven counter-clockwise, i.e. in
the forward direction. In FIG. 4, the force line during the push
stroke of actuating lever 6 is designated by A.
During this push stroke, the intermediate gear wheel 16' on intermediate
shaft 17' is also driven by the input gear wheel 14, but freewheel
clutch 19' operates in the opposite direction to that of clutch
19, so that change gear wheel 20', which meshes with gear wheel
20 is idling.
During the pull stroke of actuating lever 6, the input shaft 7
and hence input gear wheel 14 are driven clockwise. Accordingly,
the intermediate gear wheel 16 is driven counter-clockwise, so that
the freewheel clutch 19 does not take along the change gear wheel
20. The intermediate gear wheel 16' also turns counter-clockwise,
and through the now operative freewheel clutch 19' will take along
change gear wheel 20', causing it to rotate counter-clockwise. The
change gear wheel 20' meshes with the change gear wheel 20, and
will cause the latter to rotate clockwise, whereby change gear wheel
20 will again drive output gear wheel 21 counter-clockwise, so that
the rear chair wheel move in the forward direction also during the
pull stroke. The force pattern resulting from the drive during the
pull stroke of actuating lever 6 is indicated in FIG. 4 by the force
line B.
When engaging shaft 24 is displaced so that the shifting boss carried
by it forces the row of balls 23 of gear wheel 21' outwardly, a
connection is effected between the output gear wheel 21' and output
shaft 22. The wheel chair is driven in exactly the same way as described
above for the forward direction. During the push stroke of actuating
lever 6, gear wheel 21' will be driven through the two change gear
wheels 20, 20', and during the pull stroke of actuating lever 6
gear wheel 21' will be driven direct through change gear wheel 20'. |