Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02965721 2017-04-25
SIDE RAIL FOR HOSPITAL AND/OR NURSING-CARE BED
The invention pertains to a hospital and/or nursing-care bed with a side rail
and to a
side rail for attachment to a corresponding bed.
Side rails on beds are generally known. The function of a side rail is to
protect the
person lying in the bed from rolling out of the bed while sleeping, for
example, in which case
the patient could fall on the floor and suffer an injury. Depending on the
concrete conditions
of use, it can be necessary for the side rail to extend down the entire length
of the bed or
down only part of that length. A side rail can be provided on both long sides
of the bed; in
the following, however, only one side rail arranged on one of the long sides
of the bed will be
considered. A side rail of similar or different design can be provided on the
other long side,
or there can be no side rail at all on the other side.
Various requirements are imposed on side rails. First, it should be as easy as
possible
to change over from the opened position, in which the long side of the bed is
free, into the in-
use or closed position. In the opened position, furthermore, the side rail
should not be
perceived as an interfering element and best of all should be completely
invisible. In
addition, the side rail should have sufficient stability but also be easy to
manufacture at low
cost. In particular, the side rail should be set up so that it can be brought
first into a raised
position, whereupon it should also be possible, as the user or nursing staff
chooses, to have
the rail leave part of the long side of the bed free or to have the rail close
off the long side
completely.
The goal of the present invention is to provide a new side rail which offers
an
improved way of meeting the requirements cited above. This goal is achieved
with the bed
and the side rail according to the independent claims. Advantageous
elaborations can be
derived from the subclaims.
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A hospital and/or nursing-care bed comprises a side rail comprising at least
two posts,
each of which is supported pivotably relative to a frame of the bed around a
lower center of
rotation, these posts being pivotable between at least one raised position, in
which the side
rail is in the in-use position, and a lowered position, in which in particular
the posts are
aligned essentially in the longitudinal direction of the bed. In addition, the
side rail
comprises at least one bar, which is supported pivotably relative to the posts
around upper
centers of rotation on the post, wherein in particular a device for latching
or clamping the side
rail in the in-use position is provided. The latching or clamping device
comprises in
particular a means which which works by mechanical latching interacting
(positive
connection) or the force-friction-method. When the hospital and/or nursing-
care bed is in the
state in which the side rail is in its in-use position, a spring element
exerts a force on the side
rail which acts to keep the rail in the in-use position; the amount of this
force is at least 15 N,
which acts on the free end of one of the posts in the longitudinal direction
of the bar. In
alternative embodiments, this force can be in the range of 25-80 N, and
preferably of 35-65
N. This force is preferably measured in the horizontal direction. The opening
angle of the
side rail is preferably 90 , in which case the posts are vertical. Thus the
amount of force
exerted by the spring element on the side rail in its in-use position is
sufficient to prevent the
side rail from being pivoted unintentionally into the not-in-use position. It
was recognized
that the forces which a person exerts on the side rail when supporting himself
on it are
essentially vertical. Thus a maximum vertical force of 400-600 N can be
present. The
support force can typically comprise a horizontal component of approximately
10-20 N.
Thus a relatively small force of at least 15 N is enough to ensure that, if
the latching device of
the side rail were to be unintentionally released, the side rail will not move
out of the in-use
position. It is also taken into account in this analysis that, before the side
rail is pivoted
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downward into the not-in-use position, its center of gravity is first raised
slightly from its
location when in the in-use position, after which the remaining part of the
movement occurs.
It is possible to obtain a lever arm as the perpendicular distance of a center
of rotation
of the support of a post relative to the bed frame from the spring plane
obtained by
connecting the two bearing points of the spring element. When the side rail is
in the in-use
position, the lever arm is situated in the range of 80-100% of the distance of
the center of
rotation of the post from the bearing point coupled to the post. 100% is
defined as the
maximum value. The cited percentage range describes ensures that the spring
element has a
relatively long lever arm for the purpose of producing a large amount of
torque on the side
rail to move it into the in-use position.
When the side rail is in the not-in-use position, the previously mentioned
lever arm
can preferably be situated in the range of 0-20% of the distance of the center
of rotation of the
post from the bearing point coupled to the post. In this position, therefore,
the influence
exerted by the spring element on the side rail is reduced. As a result, the
force of gravity
exerted on the side rail predominates, and the side rail can rest stably in
the not-in-use
position.
The first end of the spring element, furthermore, can be supported pivotably
relative
to the frame of the bed, while the second end is supported pivotably relative
to one of the
posts. What is obtained, therefore, is a certain angle between the first end,
the second end,
and one of the centers of rotation of the posts relative to the frame of the
bed, and this angle,
in the not-in-use position, is in the range between ¨15 before and +100 after
the reversal
point of the spring element at maximum compression. This teaching also means
that, when
the not-in-use position is present, the spring element exerts only a small
amount of torque on
the side rail.
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A hospital and/or nursing-care bed comprises a side rail comprising at least
two posts
supported pivotably around a lower center of rotation relative to the frame of
the bed, which
posts can be pivoted between at least one raised position, in which the side
rail is in the in-use
position, and a not-in-use position, in which in particular the posts are
aligned essentially in
the longitudinal direction of the bed. A bar is supported pivotably relative
to the posts around
the centers of rotation on the posts. The side rail comprises an extension
element for
extending the side rail in the longitudinal direction of the bed, wherein,
when in an
intermediate position obtained between a non-extended position and an extended
position
with the effect of increasing the length of the side rail, the extension
element is retained
and/or supported exclusively by a base body of the side rail comprising the
posts and the bar.
Upon being moved into an extended position which increases the length of the
side rail, the
extension element can be brought into engagement with a bearing which supports
the
extension element. The bearing serves to absorb the weight forces which can be
exerted on
the free end of the extension element. The term "bed frame" is understood in
particular to
mean the upper bed frame, which serves to support the mattress or the
components which
support the mattress. In this way, an extension element can be produced which
brings about a
significant increase in the length of the side rail; in addition, the
extension element is stable
enough that a person can support himself on the end of the extension element
and/or is
sufficiently effective at preventing a person from falling out of the bed.
There is in particular a distance at least 30 cm between the extension element
in its
extended position and the adjacent end of the bed,. The adjacent end in
question refers in
particular to the head end or foot end of the bed. At a distance of, for
example, 60 cm, a
person can comfortably get out of bed even if the side rail is in the
protective position. This
avoids creating the impression of being confined.
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A releasable clamping device can also be provided between the extension
element and
the base body of the side rail. As a result, the side rail is prevented from
moving into the
extended state unintentionally. Even if the extension element were to be
pulled out by only a
small amount, it would still be possible for stresses or a blockage to occur
when the side rail
is pivoted downward.
The maximum distance to which the extension element can be pulled out is
preferably
more than 60% of the distance between the pivotably supported posts of the
side rail. Almost
complete coverage of the long side of the bed can thus be achieved with only
one side rail. In
addition, an advantage is obtained with respect to manufacturing costs.
Conventional, known
side rails, which made it possible to cover a portion of the long side of the
bed, were often
designed in such a way that two independent side rails, each with two posts,
were used. Thus
a total of four posts was obtained. In the embodiment described here, only
three posts,
namely, the outside post, the middle post, and the extension post are
required. In addition,
the side rail extension can be pulled out to different degrees, so that the
user can adjust the
extension function to suit his interests. The individual parts are also
mechanically simple and
can thus be produced at low cost.
Through a combination of at least the forces of a spring element and the force
of
gravity acting on the side rail, a resultant force can act on the side rail in
such a way that,
starting from an opening angle of greater than 40 measured between one of the
posts and the
bed frame, the side rail will be pushed toward the in-use position. This angle
is measured
with the bed frame in a horizontal position. Forces produced by a damping
element can also
be operative, or several spring elements can be used. The resultant force is
defined as the
force which acts on the side rail during a pivoting movement around the
bearing points of the
side rail relative to the bed frame. The resultant force can, for example, be
measured by
means of a load cell on the upper longitudinal bar or on a cover over the
longitudinal bar.
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The action of the resultant force is thus perpendicular to the post, wherein
the length of the
post is the lever arm of the side-rail pivoting movement.
The side rail preferably comprises a dead-center point in the pivoting range
between
the in-use position and the not-in-use position; at this point, the forces
acting on the side rail
are in equilibrium. Here the angular position of the side rail is at an
opening angle of less
than 500. In the case of a normal pivoting movement, the side rail will never
persist at the
dead-center point, because, as a result of the kinetic energy involved, the
side rail will travel
through the dead-center point. If, however, a user intentionally orients the
side rail so that it
occupies this unstable position, then, as a result of the relatively small
opening angle within
the side rail, no forces will build up when the user supports himself on the
side rail. Instead,
the side rail will immediately pivot into the not-in-use position. In
particular, the side rail
comprises a dead-center point in the pivoting range between the in-use
position and the not-
in-use position at which the forces acting on the side rail are in equilibrium
and the angular
position of the side rail is at an opening angle (a) in the range of 30 10
.
In addition, an extension element is shiftable in particular toward a side
rail base body
comprising the posts and at least one longitudinal bar and serves to extend
the side rail in the
longitudinal direction of the bed. When not extending the length of the side
rail, the
extension element is held in a position relative to the side rail base body by
a releasable
retaining device.
The latching or clamping device can also comprise an actuator for unlatching
or
unclamping the side rail, wherein, when side rail is in its in-use position,
the actuating
direction of the actuator largely agrees with the direction of the opening
(lowering)
movement of the side rail. Such agreement is ergonomically advantageous,
because the user
can, with a single movement in a single direction, first actuate the actuator
and then move the
side rail down from the in-use position in the same direction. This ergonomic
design,
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however, is not used in beds according to the prior art, because it could, in
principle, be the
occasion of a certain danger. That is, if a user is supporting himself on the
side rail in such a
way that he is also surrounding or contacting the actuator, a portion of his
supporting forces
will be diverted to the actuator, which could cause the actuator to operate,
and because of the
previously mentioned ergonomic similarity of direction, this would bring about
the
downward movement of the side rail, as a result of which the user would no
longer be able to
support himself For this reason, the direction provided for the purpose of
releasing the
latching function is usually different (e.g., perpendicular or opposite) from
the fold-down
direction of the side rail.
In the present invention, however, a force preferably pushes the side rail
continuously
into the raised position, i.e., the in-use position. Thus the spring helps to
keep the side rail in
the raised position. The forces which the user exerts to support himself are
primarily vertical
forces, which, under certain conditions, can also comprise a lateral (i.e.,
horizontal) force
component. This lateral component is usually relatively small, so that the
previously
mentioned force of at least 15 N is sufficient to push the side rail into the
raised position.
In an alternative embodiment, no provisions are made for latching or clamping
the
parts of the side rail together and/or to the frame of the bed. In this case,
the side rail can be
held in its raised position exclusively by the previously mentioned force of
15 N.
Alternatively, in this embodiment, a larger force of at least 30 N can
preferably be provided,
so that even relatively strong lateral forces can be absorbed without causing
the side rail to
fold down.
Preferred embodiments of the invention are described below on the basis of the
figures:
-- Figure 1 shows a perspective view of a bed with a side rail in its not-in-
use
position;
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-- Figure 2 shows a view of the bed at the level of the bed frame with a side
rail in the
not-in-use position;
-- Figure 3 shows the side rail in an intermediate position between the in-use
position
and the not-in-use position, the viewing direction being from the interior of
the bed;
-- Figure 4 shows the side rail in its in-use position with a partially
extended
extension element, the viewing direction being from the exterior of the bed;
-- Figure 5 shows the side rail in its in-use position with a completely
extended
extension, the viewing direction being from the interior of the bed;
-- Figure 6 shows a partial side view of the side rail in the in-use position
with a
small degree of extension of the extension element;
-- Figure 7 shows a perspective view of the side rail with the extension
element in the
completely extended position;
-- Figure 8 shows a partial view of the extension element shortly before
reaching the
fully extended position;
-- Figure 9 shows a diagram of the forces acting on the side rail;
-- Figure 10 shows a view of the spring element with the side rail in the in-
use
position; and
-- Figure 11 shows a view of the side rail in the not-in-use position.
Figure 1 shows a hospital and/or nursing-care bed comprising four feet 12,
which are
attached to a lower frame (not shown). The lower frame is a carrier for the
upper frame.
This upper frame can be raised and lowered by a drive (not shown), and its
angle can be
adjusted. The upper frame serves as a carrier for the head end 5 and the foot
end 6 and also
for the lower leg rest 7, the upper leg rest 8, and the back rest 9. The
mattress (not shown)
lies on these latter, and the positions of these rests can be adjusted by the
use of drives (not
shown). On the left long side (shown at the front in Figure 1), parts of a
side rail are visible,
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namely, an outer post cover 33 of an outer post 30 and a longitudinal bar
cover 43 of an upper
longitudinal bar 40. The side rail is preferably fastened to the upper frame
of the bed. In
alternative embodiments, it can also be fastened to the lower frame. The side
rail cannot be
seen in Figure 1, because it is in its not-in-use position and is covered by a
faceplate 22. In
the not-in-use position, the upper edge is situated a few centimeters, e.g. a
maximum of 5 cm,
above the rests 7, 8, and 9 in their down positions. When the mattress is laid
on these rests,
the upper edge of the covers 43 and 33 are situated a few centimeters below
the upper edge of
the mattress. Thus a person can comfortably sit on the side of the bed such as
when leaving
the bed, for example, or when in the process of lying down, since his upper
legs will not
come into uncomfortable contact with the covers when the mattress is
compressed by the
person's weight.
The side rail, as can be seen in Figure 3, comprises a side rail base body,
which
comprises the middle post 70, the upper longitudinal bar 40, and the outer
post 30, wherein
these parts are connected to each other to form a parallelogram. The middle
post 70 is
supported rotatably around a center of rotation 72 on a middle post carrier
71. The middle
post carrier 71 is fastened either to the frame of the bed or to the faceplate
22, as desired. At
the upper end of the middle post 70 there is a rotary bearing point 45, by
which the upper
longitudinal bar 40 is supported on the middle post 70. In addition, the outer
post 30 is
supported by way of a center of rotation 32 either on the faceplate 22 or on
the bed frame.
The outer post 30, furthermore, is connected to the upper longitudinal bar 40
by a bearing
point 44. As a result of these support measures, the upper longitudinal bar 40
can be pushed
laterally, i.e., without any rotational or pivoting movement, from the rest
state of the not-in-
use position into the in-use position.
Figures 4 and 5 show the side rail in its in-use position, which is also
referred to as the
"raised" position. In the in-use position, the long side of the bed is at
least partially covered
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by the side rail, so that a person is prevented from falling out of the bed.
The protection at
the head end is more important, because the injury would be more severe if a
person were to
fall out head-first or body-first rather than feet-first. The post 70 is
called the "middle" post.
Preferably, however, it is not centered with respect to the long side of the
bed; instead, it can
be closer to the head end of the bed by a 60:40 ratio. Because a person lying
in the bed
usually has his buttocks in the middle of the bed (seen longitudinally) and
when getting out
bed pivots around the buttocks as a center of rotation, arranging the middle
post 70 exactly in
the middle would tend to interfere with the process of leaving the bed.
Additional bars, namely, the longitudinal bars 50 and 60 and the extension
bars 150
and 160, are arranged under the upper longitudinal bar 40. Only these
extension bars 150 and
160 can be seen in Figure 3. These can slide back and forth telescopically
with respect to the
longitudinal bars 50 and 60 (see Figure 4). In the present embodiment, the
longitudinal bars
50 and 60 are accommodated inside the extension bars 150 and 160. The
longitudinal bars
50, 60 are supported rotatably on the outer post 30 at the centers of rotation
54 and 64. When
the side rail is in its extended position (as will be explained further
below), it cannot be
pivoted into the not-in-use position, because the extension bars 150 and 160
are held in
narrow slideways, which prevent such pivoting movement. So that the side rail
can
nevertheless be pivoted into the not-in-use position, centers of rotations 155
and 165 (Figure
4) are provided at the connection of the extension bars 150 and 160 to the
extension post 170.
These centers of rotation are arranged on projections 158 and 168 of the
extension post
pointing toward the end of the bed, in each case at the vertical level of the
horizontal bars 50
and 60, and are long enough that, when the extension post 170 is resting
against the middle
post 70, these projections can pass through the middle post. The bearing
points 155 and 165
are located inside the mechanical linkage describing the parallelogram. As a
result, it is
possible, when the side rail is pivoted, for the above-described parallelogram
and also the
CA 02965721 2017-04-25
assembly consisting of the extension bar 150 and the horizontal bar 50 and the
assembly
consisting of the extension bar 160 and the horizontal bar 60 to rotate in
pairwise fashion
around the bearing points 54 and 155 in the one case and bearing points 64 and
165 in the
other. During this process, the individual horizontal bars 40, 50, 60 move in
parallel, offset
from each other, from the in-use position to the not-in-use position.
By means of an actuator 57, the state in which the extension post 170 and the
middle
post 70 are latched together can be released, as can be seen in Figure 6. The
actuator 57
comprises a finger area and a latching area 57a. When the extension element is
in the
pushed-in position, the latching area 57a is located inside the hollow profile
of the middle
post 70 and is pressed down by the force of a spring (not shown), so that the
side of the
latching area on the right in Figure 6 is behind the opening provided for the
extension bar 150
and thus prevents the extension element from be pulled out in the longitudinal
direction of the
bed. The use can put his finger in the finger area between the middle post 70
and the
extension post 170 (see Figure 3) and lift the actuator 57 to release the
latch. When the side
rail is in the in-use position, the extension element can then be pulled out.
The actuator 57 is
preferably located at the height of the bed frame 3 or higher. Alternatively,
the actuator can
be located at the level of the upper edge of the mattress or higher. In these
ways, it is ensured
that the user can easily grip the actuator 57. The latching area 57a of the
actuator 57 is
preferably a mechanical component which acts on two parts of the side rail
which are
pivotable with respect to each other and which, when in the latching position,
prevents these
parts from pivoting relative to each other. These pivotable parts comprise in
particular the
posts 30, 70 and the horizontal bars 40, 50, and 60.
The extended position is shown in Figures 5 and 7. The extension element 170
comprises the extension post and three bars 140, 150, and 160. In the extended
position, the
extension post 170, which, when in the states according to Figures 1 and 2,
was directly
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adjacent to the middle post 70, i.e., at a distance of approximately 2 cm from
it, is now a
certain distance away from that post as the result of a shifting movement
toward the foot end
6 of the bed. The upper extension bar 140 is pivotably supported in a rotary
bearing 145 at
the upper end of the extension post 170. When the side rail is in the raised
position, the entire
extension bar 140 is is inside a cavity in the upper horizontal bar 40 and is
free to move
axially back and forth there. So that the side rail can be raised, the rotary
bearing 145 is
coaxial to the previously mentioned bearing 45 of the middle post 40 for the
upper horizontal
bar 40 when the rail is in the not-in-use position, as can be seen in Figure
5. The upper
horizontal bar 40 comprises a U-shaped cross section (not shown), wherein the
legs of the Ii-
section serve as the bearing points of the rotary bearing 45. The extension
bar 140 is
supported between the legs of the U-section.
When the extension element 170, 140, 150, 160 is pushed into the main body of
the
side rail or is in an intermediate position, the extension element 170, 140,
150, 160 is guided
relative to the bars 50 and 60 by guide openings in the center post 70 and the
linear guides.
The free end of the extension element is then not in contact with any other
part of the bed or
of the side rail. When the extension element is pulled out even more from an
intermediate
position, the extension post 170, as can be seen on comparison of Figure 7
with Figure 8,
arrives in contact with the slide surface 90. The slide surface 90 is a part
of a carrier, which
is attached to a retaining web 95 on the frame of the bed. The slide surface
90 comes in
contact with a bottom surface of the extension post 170. The slide surface 90
comprises a
contact surface which ascends in the direction of the pulling-out movement of
the extension
element. As a result, the extension post 170 is raised by a certain amount to
compensate for
the lowering resulting from the clearances or tolerances within the support of
the extension
element. This amount is in particular less than 20 mm. As the pulling-out
movement
continues, a lower section of the extension post 170 comes in contact with a
capture guide 92.
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This comprises contact surfaces on both sides in the transverse direction of
the bed, which
surfaces orient the extension post 170 in the transverse direction of the bed.
At the end of the
slot-like capture guide 92, a retaining pin 94 engages with the capture guide.
The extension
post 170 comprises a compatible opening 172, in which the retaining pin 94
fits. In this way,
the extension post 170 and thus also the entire extension element are guided
in the positive
and the negative vertical directions, in the positive and negative transverse
directions of the
bed, and in the pulling-out direction. The user can thus support himself on
the extension post
170 and/or the upper bar 140 of the extension element without excessive forces
or torques
being absorbed by the main body of the side rail. Instead, such forces are
transmitted via the
retaining web 95 into the frame of the bed. Because of this arrangement, the
extension
element can be much longer than would be possible if it were supported merely
on the main
body of the side rail.
At its upper end, the middle post 70 comprises an angled portion, which points
in the
direction of the side rail, and from there a second angled portion leads to
the bearing point 45
for the upper horizontal bar 40. In this way, a free end of the upper
extension bar 140 is
obtained, underneath which an area is present which is large enough that a
user can use it to
grip the extension bar 140. This free area is called a "hand grip" 49, because
the user can use
it to raise the side rail and thus pivot it into the in-use position.
The structure described above leads to several advantages. First, operation is
very
simple. In many concrete applications, a side rail which covers only a part of
the bed,
preferably the half at the head end, is needed, because this alone in many
cases can
sufficiently reduce the danger that the person lying in the bed could fall
out. The raising
movement can be implemented by the use of the hand grip 49. When the side rail
is in the
lowered position, i.e., the not-in-use position, the user (or the nursing
staff) must merely lift
the hand grip 49 to raise the rail with a pivoting action into the in-use
position; the previously
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described latching function will then hold the side rail in the in-use
position. Several
different manipulations were required to operate the conventional, known side
rails.
The design concept described here also makes it possible to give the side rail
an
attractive appearance both when in the not-in-use position and when in the in-
use position,
which are the two most frequent situations. According to Figure 1, which shows
the not-in-
use position, it is primarily the outer post cover 33 and the longitudinal bar
cover 43 which
are visible. These covers can be provided with cushioning or an attractive
surface such as a
wood grain. The longitudinal bar cover 43 remains on the upper edge of the
side rail in the
in-use position.
When the side rail is in its in-use position and the extension element is
pushed in, a
latching device activatable by means of an actuator 47 prevents the side rail
from being
pivoted back into the not-in-use position. As shown in Figure 6, the actuator
47 is a slider or
a pin, which is activatable in the longitudinal direction of the bed. It is
supported in a cavity
in the extension post 170. The actuator 47 is pushed by a spring against a
section of the
middle post 70 and comprises a projecting pin 48, which can fit into a
receptacle in the
middle post 70. When the pin 48 is engaged in this way, the pivoting movement
of the
middle post relative to the upper longitudinal bar is blocked, and the side
rail therefore cannot
be pivoted into the not-in-use position.
The opening angle a, which is 0 in the not-in-use position and 90 in the in-
use
position, is indicated in Figure 3. The side rail is pushed into the in-use
position by the spring
element 39 arranged between the frame of the bed or the faceplate 22 and the
outer post 30.
When the forces acting on the side rail are measured at a point P, located on
the longitudinal
bar cover 43, the diagram shown in Figure 9 is obtained, which shows the force
Fh in the
horizontal direction r and the force Fv in the vertical direction. At an
angular position of 90 ,
the side rail is being pushed into the in-use position with a force Fh of 50
N. This force is
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produced primarily by the spring element 39 and to a lesser extent by the
weight forces of the
side rail. The forces exerted by the spring element 39 increase as the opening
angle
decreases. Conversely, as the opening angle a decreases, the weight forces
actuating on the
side rail increase. There is therefore a dead-center point at approximately
300, at which the
forces acting on the side rail are in equilibrium. The range in which the dead-
center point is
located is in particular between 20 and 45 . As the opening angle decreases,
the proportion
of the weight forces acting on the side rail increase. For reasons of
measurement technology,
the force Fv is measured in the vertical direction at these angles. This force
increases to
approximately 30 N by the time the opening angle a reaches 0 . That is, when
the user wants
to bring the side rail into the in-use position, he must apply a force of 30 N
to raise it from the
not-in-use position.
The spring element 39 is preferably configured as a gas spring. In its
extended state,
i.e., the state in which the side rail is in the in-use position, the force is
approximately 450 N
and increases to about 1,000 N as the spring is being compressed. The decrease
in the force
Fv in the not-in-use position is achieved in the form of a mechanical
transmission, in that, in
the not-in-use position, the two end points of the spring element 39 lie more-
or-less on the
same line as the bearing point 32 of the outside post 30.
The dead-center point is intentionally selected to be about 30 . If, as in the
embodiments known from the prior art, the dead-center point is in the range of
60-80 , the
following danger could arise: A person could be supporting himself on the side
rail situated
at the dead-center angular position. Because, at these angles, the resultant
force is relatively
close to the center of rotation of the side rail, the side rail can absorb a
significant amount of
force. When, as soon as a certain force is exceeded, the side rail is folded
down by a pivoting
movement into the not-in-use position, the opposing force decreases
significantly and
spontaneously. This loss of resistance comes as a surprise to the user, so
that he could fall
CA 02965721 2017-04-25
and injure himself When the dead-center point is at approximately 300,
however, it is easy
for the user to realize that the side rail is in an unstable position. At
these opening angles, the
load which the person is exerting by supporting himself does not lead to an
opposing force,
because the side rail will pivot downward immediately. Thus the build-up of
forces
described above and their subsequent disappearance do not occur. The user
would notice
immediately that the side rail cannot offer any support in this angular
position and would
never even attempt to support himself on the side rail. As previously
mentioned already, the
bed frame and/or the upper bed frame can be pivoted in such a way that the
head part is
elevated. Pivot angles in the range of 14-18 are usual. The selected dead-
center point of 30'
makes it possible, whatever pivot angles of the bed frame are chosen, for the
side rail to pivot
reliably into the not-in-use position; in addition, this angle excludes the
possibility that a
dangerous situation can occur when the user supports himself on a side rail
located at the
dead-center point. Moreover, the angular range of the dead-center point is so
small that, in
practice, the side rail does not remain within the range of angles of the dead-
center point for
any significant period of time when the side rail is in use.
As previously explained, the actuator 47 makes it possible to release the
device which
latches the side rail in the in-use position. The release direction r is in
the longitudinal
direction of the upper bar 40, i.e., in the direction toward the foot end of
the bed. This
direction corresponds to the pivoting direction of the side rail at the
beginning of the pivoting
movement from the in-use position to the not-in-use position. In the case of
the conventional,
known side rails which comprise a latching device, it is always the case that
the actuating
direction of the unlatching movement is different from the movement of the
side rail which
the unlatching makes possible. According to the teaching of prior art this is
important,
because it can avoid a situation in which a person is bracing himself in one
direction on the
side rail (and in particular on the actuator) and the forces exerted on the
actuator by the
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bracing action open the side rail. This means that it would be possible for
the side rail to be
opened unintentionally. Thus the side rail, as it is moving to the lowered
position, would not
offer any support to the person bracing himself against it. Because of the
previously
described force Fh, which holds the side rail in the in-use position with 50
N, however, the
goal is achieved that an unintentional opening of this type cannot occur. That
is, it was
recognized that forces on this order of magnitude cannot be produced
unintentionally by a
user. Thus, in contrast to the conventional understanding, the release
direction of the latching
device can be oriented in the same direction as the down-pivoting movement of
the side rail.
Because this identity of directions corresponds to the conventional thinking
of the user, it was
possible to increase the intuitiveness and ergonomics with which the side rail
is operated.
The terms "horizontal" and "vertical" used above pertain to a bed in which the
bed
frame is oriented horizontally. In the case of a bed frame pivoted to some
other angle, the
relationships explained above apply in corresponding fashion.
Figure 10 shows the view designated "A" in Figure 1, except that here the
faceplate
22 has been removed, and the side rail is in the in-use position. The frame 3
of the bed 1
serves as a support for the outer post 30 at the bearing point 32. A bearing
39a for the gas
compression spring 39 is also arranged on the frame 3 of the bed. The gas
compression
spring 39, which is also referred to as the "spring element", comprises a
piston, which can be
pushed toward a base body. The spring travel comprises a distance of 50 mm,
wherein the
distance traveled by the spring in preferred embodiments can be in the range
of 30-90 mm.
The angle y between the bearing point 39b, the bearing point 39a, and the
bearing point 32 is
preferably in the range between ¨50 and +25 , depending on the position of the
side rail.
When the spring begins to travel, i.e., at the beginning of the process of
compressing the
spring element, the force is 450 N (preferably in the range of 300-700 N) and
increases to
about 800 N at the end of the travel. In addition, a damping element is
incorporated into the
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gas compression spring, so that the gas compression spring pushes the side
rail toward the in-
use position at limited speed. As shown in Figure 10, the bearing point 39b is
located more-
or-less vertically above the bearing point 32, and the bearing points 39a and
32 are located on
the same horizontal plane. Thus a long lever arm h is obtained for the
exertion of force by
the spring element on the side rail.
Figure 11 shows the not-in-use position. The gas compression spring 39 is
exerting
its maximum amount of force, because it is compressed all the way. At the same
time, the
bearing points 39a, 39b, and 32 all lie on more-or-less on the same line. That
is, when the
side rail is being pivoted within a certain range of angles near this
position, the gas
compression spring 39 undergoes a much smaller degree of compression than is
possible in
the vicinity of the in-use position. Expressed differently, the lever arm h
(see Figure 10) is
relevant to the exertion of force by the spring element on the outer post 30.
This arm is the
perpendicular distance from the bearing point 32 to the line obtained by
connecting the
bearing points 39a and 39b of the spring element 39. This lever arm is close
to zero in the
not-in-use position and has its maximum value in the in-use position.
Preferred are
embodiments in which these conditions are kept in the range of 20%.
Instead of being arranged on the outer post 30, the spring element 39 could
also be
arranged on some other post such as in particular the middle post 70. It is
also possible to use
a plurality of spring elements. Instead of the compression spring described
here, it tension
spring could also be used.
List of Reference Numbers
1 bed
3 bed frame
22 faceplate
30 outer post
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32 center of rotation
33 outer post cover
38 stop
39 spring element, gas compression spring
39a, 39b bearing points
40 upper longitudinal bar
43 longitudinal bar cover
47 actuator
48 pin
49 hand grip
50, 60 bars
57 gripping piece (57a = latching area)
70 post (middle post)
71 middle post bearing
72 center of rotation of the middle post
90 slide surface
92 capture guide
94 latching pin
95 retaining web
170 extension post
172 opening
19
