Note: Descriptions are shown in the official language in which they were submitted.
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Title: Running gear for a drive mechanism for a rail-guided
displacement device.
The invention relates to an assembly of a running rail
and a running gear for the drive mechanism for a rail-guided
displacement device, such as a stair lift. Such assembly is
known from GB 2 168 019.
This known assembly comprises a running gear having a
main frame and a pair of pivotable subframes, each of the
subframes provided with guide wheels running on either side of
the ~~rn~.ng rail. The subframes are each pivotable around an
axis parallel to the axes of the guide wheels, extending
perpendicular to the length of the running rails in the middle
between said axis of said guide wheels. The facing sides of
the subframes are provided with a curved surface having teeth,
said teeth of said subframes meshing and providing for a
mechanical mirror. Between the pairs of guide wheels on both
subframes two further guide wheels are provided, positioned on
both sides of the running rail. One of these further guide
wheels is coupled to a pivotable rod which, through teeth and
cooperating teeth on one of the subframes provides for
pivoting of said subframe when running through a curve in a
plane perpendicular to the axis of the guide wheels, which
pivoting provides for the mirrored pivoting of the other
subframe by means of the meshing teeth. Furthermore, a drive
wheel is provided for movement of the running gear along said
guide rails. The rotation axis of the drive wheel lies within
the mirror plane between said subframes.
In. this known running gear the chair is coupled to two
flanges extending on either side of the running gear, in which
bearings are provided for the pivoting axis of both subframes,
as well as thelaxes of the pivoting member providing for the
mirrored movements of said subframes. Therefore the chair
follows the movements of the rotation axes of said subframes,
which means that there will be movement of the chair relative
to the drive wheel.
.,. In using an assembly of this known type load carrying
means will move in a direction perpendicular to the running
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rail, relative to the drive wheel when negotiating curves.
Therefore, when the drive wheel is driven with a constant
speed the chair is accelerated and decelerated when
negotiating said curve, since the path of travel of the chair
is either longer or shorter than the relative part of the
guide track, depending on whether the curve is facing downward
or upward_ These accelerations and decelerations should be
avoided for comfort of a passenger or other load and in order
to keep the forces exerted on the running gear as low as
possible.
This known assembly furthermore involves the drawback
that when traversing a curve, the guide wheels will assume an
undesired position relative to the running rail, because the
position of the guide wheels relative to the rigid supporting
part, made up of at least the two flanges and the axis of the
guide wheels remains the same. In particular for guide wheels
that do not lie in or parallel to the plane of the curve, this
means that additional wear of the different parts such as
wheel bearings and wheel tread occurs, because the axis of
rotation of the re7_evant guide wheel is not at right angles to
the tangent to the curve part in which the guide wheel is
located. In other words, when traversing the curve, the tread
of the wheel in question is always slightly oblique relative
to the instantaneous line of movement to be travelled thereby.
This applies to driven as well as to non-driven running gears
of the known type.
further assembly of the above-mentioned type is known
from practice and is supplied by the firm of Thyssen de Reus,
Krimpen aan de IJssel, the Netherlands.
The known running gear consists of a profiled guide rail
along which a displacement device in the form of a lift for
disabled persons is displaced. The drive of this running gear
is provided through cooperation of, for instance, a toothed
drive wheel included in the running gear and a gear rack
provided on tYie rw~ning rail. To ensure that the drive wheel
remains in contact with the gear rack, a set of guide wheels
.:is provided on both sides of the rail and on both sides of the
drive wheel. The guide wheels are rotatable about shafts that
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are fixedly connected to a supporting part, which supporting
part moreover carries the drive wheel and a drive motor, if
any.
The rigid supporting part of this known running gear has
the advantage that thus a proper contact between the gear rack
and the drive wheel is obtained and maintained, at least in
the case of a relatively straight or only slightly bent
running rail. When sharper curves are traversed, such a device
has the drawback that the guide wheels should have a play such
that they can move along both on the outside and on the inside
of the curve without the drive wheel either moving away too
far from the running rail, if the drive wheel is located on
the inside of the curve in the running rail, or being pressed
too tightly against the running rail or the gear rack, if the
drive wheel is located on the outside of the curve. 2n the
first case, the contact bet~Neen the drive wheel and the gear
rack will get lost, in the second case the drive wheel may
seize and/or damage may be caused to the drive wheel and the
gear rack. This problem can slightly be overcome by shortening
the distance between the guide wheels on both sides of the
drive wheel, but this affects the stability of the running
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gear adversely, which is undesirable, in particular in the
case of, for instance, passenger lifts, which require that the
user's safety be guaranteed at all times.
It has already been proposed to position the guide wheels
on both sides of the running rail further apart than the width
of the intermediate running rail. Although this enables a
curve to be traversed more properly, it will also involve
instability of the running gear, and, accordingly, of the
stair lift, because at least in a straight running rail
portion, the guide wheels then no longer abut against the
running rail. Hence, for safety reasons, such an embodiment is
less suitable.
The object of the present invention is to provide an
assembly of the type described in the preamble of the main
claim, with the drawbacks mentioned being avoided, while the
advantages thereof are retained. To that end, in accordance
with the invention, an assembly is characterized by the
features of the characterizing part of claim 1.
In this contest, a mechanical mirror can be interpreted
as a coupling mechanism providing that the movement of a first
part effects, in a mechanical manner, a movement of a second
part coupled thereto, the movements of the first and the
second part always being each other's mirror image in a plane
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of symmetry. This plane of symmetry is in a plane lying
between the first and the second part. The position of the
plane of symmetry at right angles to the driving direction of
the running gear can be understood to mean that the direction
of movement of the running gear at the location of the plane
of symmetry extends at least substantially as a normal to the
relevant plane of symmetry.
A running gear according to the invention offers the
advantage that the sets of guide wheels can move relative to
each other so that to each set of guide wheels it applies that
the plane in which the axes of the relevant guide wheels are
located intersects the running rail at right angles, i.e_ each
guide wheel of the running gear can continuously be held in
such a position relative to the running rail that the tread
thereof is located parallel to a tangent to the relevant part
of the curve, so that when a curve is being traversed, each
running wheel can move through that curve while rolling in an
optimum manner, without making a combined rolling and
dragging, dribbling movement. Moreover, a running gear
according to the invention offers the advantage that each
movement of one of the frame parts is mirrored by the frame
part following or preceding it. As a result, when for instance
a curve is run into or traversed, the position of the relevant
frame part is adjusted by the leading guide wheels, so that
the guide wheels practically follow the ideal line_ By the
coupling means, the position of the or each other frame part
is adjusted to the curve to be traversed, as a result of which
the guide wheels of this frame part, too, follow the ideal
line. In this respect, the division into a number of frame
parts has the advantage that the running gear can be guided
through a relatively sharp curve without causing problems with
the guide wheels, while the sets of guide wheels can have a
relatively large mutual distance, so that a proper stability
of the running gear is maintained.
In an advantageous embodiment, a running gear according
to the invention is characterized by the features of claims 2
°and 3.
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Because of the arrangement of a drive wheel with an axis
of rotation located in the plane of symmetry, the distance
between the drive wheel and the running rail is fixed at all
times, because in this arrangement, the drive wheel, like the
guide wheels, follows a path having a bend radius whose
momentary center always coincides with the center of the curve
that is momentarily traversed. Consequently, the distance
between the drive wheel and the running rail almost does not
change during use, regardless of the relative position of the
dive wheel in respect of the running rail. This means that in
a particularly simple manner, a drive track can be fitted with
which the drive wheel can cooperate. The drive track can for
instance be approximately identical in form to the form of the
path described by the running rail.
Preferably, the drive track is ffixedly connected to the .
running rail.
In further elaboration, a running gear according to the
invention is further characterized by the features of claim 5.
A mechanical mirror that functions three-dimensionally
offers the advantage that the running gear can thus be guided
over running rails containing double-curved curves_ For
instance, a running rail along the inside of a curve in a
stair, with the stair direction changing and, moreover, the
stair sloping.
Advantageous embodiments of a running gear according to
the invention are further characterized by the features of
claims 6-10.
In a ffirst particularly advantageous embodiment, a
running gear according to the invention, in particular the
coupling means thereof, is characterized by the features of
claim 11_
By constructing the coupling means as a pin and a bowl-
shaped recess cooperating therewith, a particularly simple,
direct-acting aid virtually true mechanical mirror is
obtained. Such a construction can be manufactured and ,
maintained in a relatively cheap manner.
In a second particularly advantageous embodiment, a
running gear according to the invention, in particular the
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coupling means thereof, is characterized by the features of
claim 12.
In this embodiment, it is provided that when a curve is
being traversed, the coupling means do not extend beyond the
contours of the running gear, or at least of the frame parts.
After all, in this embodiment, the outer second coupling bars
define an approximately cylindrical space, within which space
the entire coupling means remain in this embodiment, also
during deformation thereof when a curve is being traversed.
Alternative embodiments of a running gear according to
the invention, in particular the coupling means thereof, are
characterized by the features of claims 13 and 14.
The invention further relates to a lift assembly
comprising a supporting part such as a chair or platform, a
running rail and a running gear according to the invention.
In an advantageous embodiment, such a lift assembly is
characterized by the features of claim 16.
By utilizing a single running rail on which the running
gear is borne, which running rail has a substantially circular
section, the rurnning rail can be manufactured and fitted in a
- particularly simple manner, also in the case of, for instance,
stairs having a steep course and/or short curves.
To explain the invention, exemplary embodiments of a
running gear will hereinafter be described, with reference to
the accompanying drawings, wherein:
Fig. 1 schematically shows an embodiment of a stair lif t
comprising a running gear according to the invention;
Fig. 2 schematically shows, in side elevation, a running
gear according to the invention, on a straight running rail;
Fig. 3A schematically shows, in side elevation, a running
gear according to Fig. 2, on a concave-curved running rail
with third set of guide wheels taken, drive wheel and bridge
piece taken away;
Fig. 3B schematically shows, in side elevation, a running
gear according to Fig. 2, on a convex-curved running rail with
third set of guide wheels, drive wheel and bridge piece taken
away;
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Fig. 4A -schematically shows, in top plan view, a running
gear according to Figs. 2 and 3, on a straight running rail
with third set of guide wheels, drive wheel and bridge piece
taken away;
Fig. 4B schematically shows, in top plan view, a running
gear according to Figs. 2 and 3, on a curved running rail with
third set of guide wheels, drive wheel and bridge piece taken
away;
Fig. 5 schematically shows, in front view, a running gear
according to Fig. 1, with cut-through running rail;
Fig. 6 schematically shows a first alternative embodiment
of the coupling means; and
Fig. 7 schematically shows a second alternative
embodiment of the coupling means.
Fig. 1 shows, in front view, a portion of a stair lift 1,
positioned on a running rail 2 by means of a running gear 3.
The running rail 2 for instance extends along the inside of a
curved stair, i_e. that side of the stair which has the
shortest bend radiuses. Hence, the running gear 3 should be
capable of moving through relatively short curves while a
flowing pattern of movement of the stair lif t 1 should
nevertheless be guaranteed and, moreover, the chair 4 or
platform or any other supporting means thereof should
continuously be held in the desired straight position, for
instance by a tilting mechanism 15, not further described. For
that purpose, it is necessary that the position of at least
the running gear 3 relative to the running rail 2 be known. An
advantage of only one running rail 2 instead of the
conventional dual running rails is that this single running
rail 2 is easier to manufacture, in particular when a running
rail of a substantially circular section is opted for_
Moreover, by such a stair lift, considerably less space is
occupied than by a conventional stair lift having two rails,
while further, the advantage is achieved that the stair lift
can be provided on that side of the stair that is not or only
minimally used by users of the stair who are not dependent on
the stair lift 1, so that these users of the stair are not or
only minimally hindered by the stair lift.
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The running gear 3 comprises a bridge piece 5, a first
frame part 6, a second frame part 7, a first set of guide
wheels 8, a second set of guide wheels 9, a third set of guide
wheels 10 and a coupling device 11. The third set of guide
wheels 10 comprises a toothed drive wheel 12 engaging a gear
rack 13 provided on the running rail 2. In Fig. 1, this third
set of guide wheels is shown only schematically and will be
further discussed hereinbelow. The bridge piece 5 comprises
means 14 for supporting a load, for instance a tilting
mechanism 15. These load-bearing means can for instance
comprise a chair, platform, hook or another supporting means.
For simplicity's sake, an embodiment of a stair lift with
chair is shown.
The first frame part 6 is connected to the bridge piece 5
via a first cardan suspension 16, the second frame part 7 is
connected thereto via a second cardan suspension 17. The first
cardan suspension 16 comprises a first frame swivel axle 19 in
the first frame part 6 which, in Figs. 1 and 2, extends
perpendicularly to the plane of the drawing and is connected,
via a first frame rotary shaft 20, to the bridge piece 5.
Preferably, the first frame swivel axle 19and the first frame
rotary shaft 20 intersect perpendicularly, with the first
frame rotary shaft 20 in Fig. 1 lying in the plane of the
drawing. Similarly, the second frame part 7 is connected, via
a second frame swivel axle 21 and a second frame rotary shaft
23, to the bridge piece 5. Each frame part 6, 7 can move
three-dimensionally relative to the bridge piece by means of
the relevant cardan suspension 16, 17.
The facing ends 24, 25 (Figs. 3, 4) of the frame parts 6,
7 are coupled to each other by the coupling means 11, which
form a mechanical mirror. In this connection, a mechanical
mirror can be interpreted as a coupling mechanism ensuring
~ that the movement of the first frame part 6 effects, in a
mechanical manner, a movement of the second frame part 7
- 35 coupled thereto, the movements of the first 6 and second frame
part 7 always being each other's mirror image in the plane of
symmetry S lying between the two frame parts 6, 7. This
applies to substantially all movements of the two frame parts
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6, 7 with a movement component in a direction parallel to the
plane of symmetry S _
The coupling means 11 as shown in Figs. 1-5 comprise a
pin 27 extending from the end 24 of the first frame part 6 and
having a slightly convex head 28, and a recess 29 provided in
the end 25 of the second frame part 7, which end 25 faces the ,
end 24 of the first frame part 6. The pin 27 extends into the
recess 29 at least by the head 28 thereof, the head 28 having
a portion of its surface abutting against the inside surface
of the recess 29.
Adjacent the second end 26A located opposite the first
end 24 of the first frame part 6, on the side thereof facing
away from the bridge piece 5, the first set of guide wheels 8
is connected thereto via a bracket 30 or a life construction.
In a similar manner, the second set of guide wheels 9 is
connected to the second end 26B facing away from the first end
of the second frame part 7. Each set 8, 9 comprises three
spaced-apart wheels, rotatably mounted on rotary shafts 32a,
32b, 32c, so that the wheels 31 have their treads 33 abutting
20 against the outside of the running rail 2. In each case, the
rotary shafts 32a-c enclose an approximately perpendicular
angle with a tangent K to the running rail 2 at the location
of the contact surface between the running rail 2 and the
tread 33 of the relevant guide wheel 31. As appears in
25 particular from Fig: 5, the running rail 2 has a circular
section, with the guide wheels 31 of each set 8, 9 being
staggered about 120° relative to each other, so that the
running rail 2 is effectively enclosed between the guide
wheels 31 of each set 8, 9, while the guide wheels 31 can move
rollingly across the surface of the running rail 2.
By at least two of the rotary shafts 32a-c of each set, a
first plane V1, V2 is defined (Figs. 2-4) which continuously
extends approximately at right angles to each tangent K to the
running rail 2 at the location of the contact surfaces between
the relevant guide wheels 31 and the running rail 2.
Preferably, the distance P between the first 19 and the second
frame swivel axle 21, respectively the first 20 and the second
frame rotary shaft 23, is equal to half the distance D between
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the first planes Vl, V2. Also to the angle P enclosed between
the planes V1 and V2, it applies that it is twice the angle P2
enclosed between the imaginary lines N1 and N2 extending from
the center C of the bend momentarily traversed by the running
gear, through the axes of rotation 19 and 21 respectively
a (Figs. 3A, 3B) or the axes of rotation 20 and 23 respectively
(Figs. 4A, 4B). Accordingly, a movement of the first end of
each frame part 6, 7 (or at least at the plane of symmetry S)
results in an equally great but opposite movement of the
opposite end of the relevant frame part 6, 7 (or at least at
the relevant set of guide wheels 8, 9), relative to the bridge
piece 5. Because of the coupling of the two frame parts 6, 7
by means of the coupling means 26, the movements of the first
end 24 of the first frame part 6 are imposed on the first end
25 of the second frame part and vice versa, mirrored relative
to the plane of symmetry S. In the embodiment shown, this
applies three-dimensionally.
The third set of guide wheels 10 is fixedly connected to
the bridge piece 5 and comprises at least two running wheels
34 rolling against the running rail, for instance by an
hourglass-shaped or double conical tread, to save space. The
third set 10 also comprises a drive wheel 12 constructed as
gearwheel and capable of meshing with a gear rack 13 provided
on the running rail (Fig. 5). Preferably, the axes of rotation
of the running wheels 34 and the drive wheel 12 lie in the
plane of symmetry S. The drive wheel 12 can be driven for
moving the running gear along the running rail 2, for instance
by means of a motor 35 mounted on the bridge piece 5.
With reference to the drawings, the movements of a
running gear according to the invention are further described
as follows. For simplicity's sake, the behavior of the running
gear is described only in a bend lying in a vertical plane,
parallel to the plane of the drawing in Figs. 2 and 3.
However, it is understood (Fig. 4) that corresponding
movements occur when a bend lying in one plane is traversed,
so that particular advantages are achieved when a randomly
bent running rail is traversed.
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Fig. 2 shows the running gear 3 disposed on a straight
portion of a running rail 2, i.e. with an endless bend radius.
The first planes V1 and VZ and the plane of symmetry S extend
parallel to each other. When moving through a bend in the
r
5 running rail 2, the guide wheels 31 of the first set 8 with
the second end 26 of the first frame part 6, relative to the
bridge piece 5 and the third set 10 connected thereto, are
urged in a direction of displacement, in Fig. 3A in upward
direction. The lever action of the first frame part 6 around
10 the first frame swivel axle 19 causes the opposite first end
24 to be pressed downwards through the same distance, with the
head 28 of the pin 27 being pressed downwards as well. This
head moves through a path of movement along the inside of the
recess 29_ As a consequence, the first end 25 of the second
frame part 7 is pressed down as well, approximately through
the same distance as the first end of the first frame part 6.
The lever action of the second frame part 7 around the second
frame swivel axle 21 causes the opposite second end 26 of the
second frame part 7 to be pressed upwards, also through the
same distance. Because the guide wheels 31 in the second set 9
fittingly enclose the running rail 2 and hence cannot move
along upwards relative to the running rail, the vertical
distance between the bottom side of the bridge piece 5 and the
guide wheels is reduced.
When the running gear 3 is moved along the running rail
2, the two first planes Vl, V2 and the plane of symmetry S will
intersect in a line C extending through the center of the bow
portion of the bend wherein the running gear 3 is located at
that given moment (Figs. 3 and 4). This means that the guide
wheels 31 are continuously held in an optimum position
relative to the running rail, which prevents the guide wheels
31, 34 from making a combined rolling and dragging, dribbling
movement over the running rail or from moving around its own '
axis of rotation 32 in another manner different from rolling.
Moreover, it is thus provided that the drive wheel 12 is
always held in the same position relative to the center of the
running rail 2, and accordingly relative to the gear rack 13.
Thus, an optimally cooperating contact is provided between the
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drive wheel 12 and the tooth track of the gear rack l3.along
the entire running rail, while the guide wheels 31, 34 can
continuously be in optimum contact with the running rail 2
without requiring for instance setting means, springs or like
compensating means.
Fig. 6 shows a first alternative embodiment for a three-
dimensionally acting, mechanical mirror-forming coupling 111
for use in a running gear according to the invention.
Identical parts are designated by corresponding reference
numerals. This coupling according to Fig. 6 comprises a first
annular disk 140, a second annular disk 141, a centrally
located, straight first coupling bar 142 and three
approximately similar, curved second coupling bars 143. The
first disk 140 is mounted adjacent the first end 124 of the
first frame part 106, the second disk 141 is mounted adjacent
the first end 125 of the second frame part 107. In a centrally
located coupling point 144, each disk 140, 141 is connected,
by means of a ball joint, cardan suspension or a like
connection, to an end 145 of the first coupling bar 142, which
keeps the disks 140, 141 at least partly at a fixed distance
relative to each other. Spaced from the coupling point 144,
the three second coupling bars 143, regularly spaced apart,
are connected to the disks 140, 141 via flexible couplings
146. Each second coupling bar 143 has a part bent so that when
the two disks 140, 141 lie parallel to each other, the
flexible coupling 146 adjacent a first end 147 of a second
coupling bar 143 is connected to the first disk 140 in a
position rotated through an angle of about 180° relative to
the position wherein the flexible coupling 146 adjacent the
opposite second end 148 of the same second coupling bar 143 is
connected to the second disk 141.
The functioning of such a coupling can be understood as
follows .
The two disks 140, 141 cannot move relative to each other
. 35 other than swivelling about the ball joints in the central
coupling 144. Hence, they cannot move towards or from each
other vertically. For instance, if the first disk 140 is
swivelled from the vertical position as shown in Fig. 6 into
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the position shown in broken lines, the first end 147 of. the
relevant second coupling bar 143, which first end 147 is
located above the first coupling bar 142, is pressed in the
direction of the opposite second disk 141, with the relevant
second coupling bar 143 being displaced as a whole. As a
result, the second end 148 of the relevant second coupling bar
143 is displaced through about the same distance as the first
end. Of course, this applies to all second coupling bars 143.
Because the second end 148 of each second coupling bar 143 is
connected, via a flexible coupling 146, to the second disk 141
on a side of the central first coupling bar 140 other than the
first end of the relevant second coupling bar 143 to the first
disk 140, the second disk 141 is swivelled in a direction
opposite to the direction of movement of the first disk,
through the same angle. Thus, the movements of the first frame
part 106 are automatically transferred in mirrored fashion to
the second frame part 107.
An advantage of this embodiment is that during the
movements of the first and second frame parts, the coupling
bars remain at least substantially within the (imaginarily
enclosed) space defined between the disk parts. This means
that the coupling means do not swivel out further than the
frame parts, which has advantages in terms of space
utilization. Moreover, this prevent users of the displacement
device from being inconvenienced by the coupling means, or
prevents the functioning of the coupling means from being
disturbed by the user.
Fig. 7 shows a second alternative embodiment of the
coupling means for forming a mechanical mirror, in a two-
dimensional embodiment_ Corresponding parts are again
designated by corresponding reference numerals.
Arranged on each of the first ends 224, 225 of the first
frame part 206 and second frame part 207, which first ends lie _
adjacent each other, is a circular segment 250 provided, along
the outer surface thereof, with a row of teeth 251. In this
embodiment, the toothed circular segments 250 mesh with each
other for transferring the movememnts of the first frame part
206 to the second frame part 207 and vice versa. In a three-
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dimensional embodiment constructed in a comparable manner (not
shown), the circular segments have been replaced by spherical
segments, provided with concentric rows of teeth along their
outside surface.
The invention is by no means limited to the embodiments
shown and described in the drawings and the specification.
Many variations thereto are possible.
For instance, the running gear may have several mutually
coupled frame parts, so that still shorter bends can be
traversed without the occurrence of disturbances, while
sufficient stability is maintained. The coupling means may be
constructed in different manners. Moreover, a comparable
running gear may be used in other types of running rails, for
instance rails of a rectangular section, or with a number of
running rails next to or above each other. In addition, the
running rail may also extend in one plane only, while the
mechanical mirror may be of two-dimensional construction, as
described. The gear rack may for instance be welded on the
outside against the running rail, be constructed as a series
of holes in the running rail or be provided at a distance from
the running rail. Moreover, other drive means may be used. For
instance, the running gear may be provided, adjacent one of
the ends thereof, with a drive gear which is connected thereto
in a flexible manner and which is capable of guiding the
running gear along the running rail through pushing or pulling
action, or the drive means may for instance be mounted on one
of the frame parts instead of on the bridge piece, and a drive
wheel, if any, may have an axis of rotation which is at a
different angle relative to the running rail, for instance
horizontally, and several drive wheels may be used which may
or may not be in different positions. Further, the running
gear may be used for various uses other than the stair lift
mentioned. These and many comparable adaptations and
variations are understood to fall within the framework of the
- 35 invention.
. : aX
