U.S. patent application number 10/013038 was filed with the patent office on 2002-05-02 for telescopic column.
This patent application is currently assigned to OKIN Gesselschaft fur Antriebstechnik mbH & Co. KG. Invention is credited to Koch, Dietmar, Nijsen, Andreas Jacobus Louis.
Application Number | 20020050112 10/013038 |
Document ID | / |
Family ID | 7661846 |
Filed Date | 2002-05-02 |
United States Patent
Application |
20020050112 |
Kind Code |
A1 |
Koch, Dietmar ; et
al. |
May 2, 2002 |
Telescopic column
Abstract
The invention relates to a telescopic column with one outer and
at least one inner rod element capable of telescoping relative to
each other, where at least the outer rod element surrounds at least
one ball arrangement with at least one ball, which acts as a
rolling bearing between the outer and inner rod elements during
telescoping movement. In order to create a telescopic column which,
while having a low weight and low manufacturing costs, displays
high lateral stability, the at least one inner rod element is
provided with a longitudinal groove, which surrounds part of the
circumference of at least one ball of the ball arrangement and
serves as a ball guide. The longitudinal groove can provide two or
more laterally separated running surfaces for the at least one
ball. An area with a larger radial distance can be provided on at
least one rod element between adjacent running tracks for an
assigned ball, this being able to act as an abutment for the ball
in the manner of an overload protector.
Inventors: |
Koch, Dietmar; (Gummersbach,
DE) ; Nijsen, Andreas Jacobus Louis; (Enschede,
NL) |
Correspondence
Address: |
Christopher J. Fildes
Fildes & Outland, P.C.
20916 Mack Avenue, Suite 2
Grosse Pointe Woods
MI
48236
US
|
Assignee: |
OKIN Gesselschaft fur
Antriebstechnik mbH & Co. KG
|
Family ID: |
7661846 |
Appl. No.: |
10/013038 |
Filed: |
October 30, 2001 |
Current U.S.
Class: |
52/651.07 ;
52/848 |
Current CPC
Class: |
F16C 33/3856 20130101;
A47B 9/20 20130101; F16C 33/40 20130101; A47B 2220/0025 20130101;
F16C 29/04 20130101 |
Class at
Publication: |
52/651.07 ;
52/726.2; 52/736.1; 52/731.3 |
International
Class: |
E04C 003/30 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 2, 2000 |
DE |
100 54 236.0 |
Claims
Patent claims:
1. A telescopic column with one outer and at least one inner rod
element capable of telescoping relative to each other, where at
least the outer rod element surrounds at least one ball arrangement
with at least one ball, which acts as a rolling bearing between the
outer and inner rod elements during telescoping movement,
characterized in that the at least one inner rod element displays a
longitudinal groove which surrounds part of the circumference of
the at least one ball of the ball arrangement and serves as a ball
guide.
2. A telescopic column according to claim 1, characterized in that
the longitudinal groove provides at least two laterally separated
running surfaces for the at least one ball.
3. A telescopic column according to claim 2, characterized in that
the inside of the outer rod element surrounds part of the
circumference of the at least one ball and provides at least two
more laterally separated running surfaces for the at least one
ball.
4. A telescopic column according to claim 3, characterized in that
an area with a larger radial distance is provided on at least one
rod element between adjacent running surfaces for an assigned ball
constituting an overload protector in the form of an abutment for
the ball.
5. A telescopic column according to claim 2, characterized in that
the laterally separated running surfaces of a groove of the
radially inner and/or outer rod element enclose an angular range of
the respectively guided ball of approx. 50 degrees to approx. 120
degrees.
6. A telescopic column according to claim 1, characterized in that
the at least one rod element is manufactured from a metal sheet or
a section of tubing by a rolling method and the groove is an
impression made in the sheet or section of tubing.
7. A telescopic column according to claim 1, characterized in that
the rod elements each have two or more laterally and/or axially
separated guide areas for at least one given ball arrangement and
that the at least one ball arrangement displays two or more balls
separated in the lateral and/or axial direction or is suitable for
accommodating two or more balls separated in the lateral and/or
axial direction.
8. A telescopic column according to claim 1, characterized in that
at least one ball displays a slight oversize referred to its target
position in disassembled condition of the telescopic column and, as
a result of at least the first telescoping movement, impresses a
running surface for the intended purpose in the inner and/or outer
of the rod elements capable of telescoping relative to each
other.
9. A telescopic column according to claim 8, characterized in that
the ball is located in a longitudinal groove of at least one of the
inner and outer rod elements and two laterally separated running
surfaces are impressed in the longitudinal groove of at least one
of the inner and outer rod elements by means of a telescoping
movement.
10. A telescopic column according to claim 9, characterized in that
the ball impresses at least two laterally spaced running surfaces
in one of the inner and outer rod elements and at least one running
surface in the corresponding of the inner and outer rod elements by
means of a telescopic movement.
11. A telescopic column according to claim 8, characterized in that
the impressed running surfaces are provided with pre-machined
running grooves for the balls, where the balls are pre-machined to
the oversize of the ball existing in disassembled condition of the
telescopic column.
12. A telescopic column according to claim 1, characterized in that
at least one of the inner rod elements essentially displays a
polygonal profile and the at least one longitudinal groove is
provided in the corner area of the profile.
13. A telescopic column according to claim 1, characterized in that
at least three rod elements capable of telescoping relative to each
other are provided, which are at least partially designed as hollow
profiles in the groove area and in that the rear side of the groove
of the hollow profile of at least one rod element serves as a guide
for a ball lying radially farther inwards, which forms the rolling
bearing for the directly adjacent, radially inner rod element.
14. A telescopic column according to claim 13, characterized in
that at least three rod elements capable of telescoping relative to
each other are provided, where two or more essentially groove-like
ball guides are formed consecutively in radial direction, and in
that the connecting axis of the center points of the balls guided
in the guides lies outside the center point of the telescopic
column.
15. A telescopic column according to claim 1, characterized in that
two or more rod elements capable of telescoping relative to each
other are provided and in that, at least in pairs, the outer
cross-section of an inner rod element essentially corresponds to
the inner cross-section of the respective outer rod element.
16. A telescopic column according to claim 1, characterized in that
guide elements that absorb forces acting laterally on the rod
elements, at least after slight angling of the rod elements
relative to each other, are provided in the longitudinal direction
of the rods, above and/or below at least one ball arrangement on
adjacent rod elements.
17. A telescopic column according to claim 16, characterized in
that at least one guide element is provided that can be fixed in
position on the assigned rod element by means of a snap-in
connection and engages at least one corner of a rod element
designed as a polygonal profile and/or a groove area of a rod
element.
18. A telescopic column according to claim 1, characterized in that
at least one ball retainer is provided that displays at least two
retaining areas, which are assigned to axially and/or laterally
separated balls or ball arrangements and in that the ball retainer
extends over one side wall of an assigned rod element.
19. A telescopic column according to claim 1, characterized in that
at least one rod element is provided with at least two ball
retainers with retaining areas for running balls which extend over
only part of the circumference of the assigned rod element and in
that the ball retainers are located in diametrically opposite
positions on the rod element.
Description
TECHNICAL FIELD
[0001] The invention relates to a telescopic column with one outer
and at least one inner rod element capable of telescoping relative
to each other, where at least the outer rod element surrounds at
least one ball arrangement with at least one ball, which acts as a
rolling bearing between the outer and inner rod elements during
telescoping movement.
BACKGROUND OF THE INVENTION
[0002] Generic telescopic columns are known for a wide variety of
applications. In particular, telescopic columns of this kind are
used in variable-height furniture or furniture elements, such as
variable-height tables, desks and the like, or in other
variable-height or laterally displaceable furnishings. However,
generic telescopic columns are also used in other fields, such as
in mechanical engineering.
[0003] Generic telescopic columns are known in which the outer rod
element consists of a section of tubing with an essentially
rectangular cross-section, with a section of tubing with a roughly
oval cross-section arranged coaxially to it. Provided as the
rolling bearings between the two telescoping rod elements are
balls, which roll on the inner surface of the outer rod element and
the rounded outer surfaces of the inner rod element. It has proven
to be disadvantageous in telescopic columns of this kind that they
display a lateral stability which is insufficient for certain
applications because, when exposed to lateral forces exceeding a
certain intensity, undefined deformation of the ball running
surfaces results, particularly on the inner rod element. This
deformation also results in uncontrollable deformation of the areas
adjacent to the ball running surfaces, this resulting in
undesirable and undefined play between the telescoping rod
elements.
[0004] However, for certain applications of telescopic columns, and
especially in the furniture sector, e.g. in variable-length table
or desk legs, it is necessary to have high lateral stability, as
well as torsional stability. Although the lateral stability can be
improved by increasing the wall thickness of the rod elements, this
results in additional weight and manufacturing costs. Moreover, it
should take as little force as possible to telescope the telescopic
column.
SUMMARY OF THE INVENTION
[0005] The object of the invention is thus to create a generic
telescopic column which, while having a low weight and low
manufacturing costs, displays high lateral and torsional stability
and can be telescoped by applying little force.
[0006] According to the invention, the object is solved by a
telescopic column in which at least the inner rod element displays
a longitudinal groove, which surrounds part of the circumference of
the at least one ball of the ball arrangement and serves as a ball
guide. As a result of providing the groove, part of the
circumference of the ball is still surrounded by the groove even
after deformation of the ball running surface or of an adjacent
area of the rod element, meaning that defined guidance of the ball
is still possible. Moreover, the groove, which surrounds part of
the circumference of the ball and has a convex curvature relative
to the center point of the ball, provide a profile which is
relatively resistant to deformation when exposed to forces
perpendicular to the groove opening.
[0007] The inner rod element is preferably provided with several
ball arrangements distributed around the circumference, so that the
rod element can absorb forces in all directions perpendicular to
its longitudinal extension via the balls. In this context, all the
balls assigned to one or all rod element(s) can be guided in
longitudinal grooves that surround part of the circumference of the
respective balls and are designed as ball guides. If appropriate,
however, only some of the balls may be assigned to corresponding
longitudinal grooves.
[0008] The longitudinal grooves of the inner rod element are
preferably of linear design, although an arc-shaped, e.g. spiral,
configuration can also be used, if appropriate.
[0009] It has proven to be particularly advantageous if, in the
longitudinal groove of the at least one inner rod element, two or
more, laterally separated ball running surfaces, which preferably
run parallel to the longitudinal extension of the assigned groove,
are assigned to at least one or all of the balls. The lateral
spacing of the running surfaces permits better absorption of
lateral forces acting on the telescoping arm by the groove.
Moreover, the lateral spacing of the running surfaces makes it
possible to adjust the ratio of the movements of adjacent rod
elements relative to each other to the coupled movement of the
corresponding balls. The term "running surfaces" is generally taken
here to mean any areas of contact between the rod element and the
ball for guidance of the same. These may, for example, be of
groove-type design and of more or less great width.
[0010] Additionally or alternatively, the inner side of the outer
rod element relative to a ball arrangement can surround part of the
circumference of at least one ball, where preferably two or more,
laterally separated running tracks are provided for the respective
ball.
[0011] The number and spacing of the running tracks of the inner
and outer rod element can in each case be adapted to the lateral
forces to be absorbed and the movements of the rod elements and the
associated ball arrangements.
[0012] The longitudinal groove on the inner and/or outer rod
element can surround the respectively assigned ball(s) over an
angle of more than 20 or more than 40 degrees, in order to obtain
sufficiently defined ball guidance. The groove preferably surrounds
the respective ball(s) over approx. 50 to approx. 140 degrees or
more, particularly preferably over approx. 70 to 90 degrees. In
this context, the groove has a concave curvature towards the center
point of the ball or the essentially plane groove flanks have a
corresponding inclination. Over this angular range, the groove
preferably has a cross-section curvature that essentially
corresponds to the curvature of the ball, i.e. the groove-to-ball
distance in this area is less than approx. 1/4 or less than
{fraction (1/10)}, preferably less than {fraction (2/100)} to
{fraction (2/1000)} or less, of the ball diameter. In this context,
a groove-like area can also be formed at the inner and/or outer rod
element by laterally separated ball running surfaces, regardless of
the other geometry of the component(s) provided with the ball
guides. The laterally separated ball running surfaces of a rod
element assigned to a ball thus preferably enclose an angular range
of the guided ball of approx. 50 to approx. 140 degrees,
particularly preferably approx. 70 to approx. 90 degrees, without
being limited to this. Preferably, only two running tracks are
provided over the circumferential angles mentioned, although
several, preferably equally spaced, running tracks can also be
provided. The angular ranges mentioned have proven to be favorable,
both for obtaining high lateral stability of the telescopic column
and for achieving a ratio expedient for many applications between
the displacement movement of adjacent rod elements relative to each
other and the resultant displacement movement of the balls.
[0013] On at least one ball, or on all balls, the ball running
surfaces at the front and rear side of the ball preferably enclose
an angle of 140 to 220 degrees, more preferably 160 to 200 degrees,
and particularly preferably 180 degrees, with the center point of
the ball.
[0014] The ball running surfaces of at least one ball are
preferably located roughly at the level of at least one of the
turning points, or at least one of the end-points, of the
essentially linear sections of the side walls of the rod elements
following on from the respective groove.
[0015] The width of the ball running surfaces when the telescopic
column is operated as intended, i.e. following any necessary
running-in period but without wear phenomena on the running
surfaces, can be approx. 1 to 15%, preferably approx. 3 to 6% of
the ball circumference. Given a ball diameter of 10 mm, the ball
running surfaces thus preferably display a width of approx. 1 to 2
mm.
[0016] If at least three or more rod elements telescoping relative
to each other are provided that display two or more groove-like
ball guides in the radial direction, the connecting axes of the
center points of the balls guided or guidable in the guides, or the
extensions thereof, preferably lie outside the center point of the
telescopic column, which can be defined as its geometrical center
point or its center of gravity. This geometry makes it possible to
achieve a maximum cross-section of the rod elements and thus
maximum lateral stability of the telescopic column. The ball guides
arranged behind one another in the radial direction can be
immediately consecutive, i.e. separated only by the rod element
walls themselves, or they can also be separated from each other by
several rod elements. All the balls located in the groove-type ball
guides of the telescopic column can be of the same diameter,
although balls located between different rod elements can also have
different diameters.
[0017] Preferably, particularly if three or more rod elements are
provided, these can display an essentially polygonal profile
cross-section, such as a triangular, rectangular, pentagonal or
polygonal profile cross-section given an idealized rod geometry in
the groove areas, where the guide grooves with ball running
surfaces are preferably located in the corner areas of the
profiles. However, the cross-sections can also have a different
cross-section, such as a round, elliptical, oval or otherwise
curved cross-section.
[0018] In particular, in the case of radially separated balls
preferably separated only by rod element walls, the ball running
surfaces assigned to these balls can essentially lie on the
connecting line of the center points of the balls, particularly on
an exactly or essentially straight line. In the radial direction
referred to the respective ball, both one front and one rear ball
running surface preferably lie on the line connecting the balls.
Particularly preferably, each ball is assigned a front and a rear
running surface lying on the line connecting the two or more balls.
As a result, lateral forces can be absorbed by the balls in the
radial direction, thus obtaining a telescopic column of great
stiffness. The deviation of the ball running surfaces in the
circumferential direction of the ball from the line connecting
several balls can be 20 degrees or less, preferably 0 to 10 degrees
or less, without being limited to these values.
[0019] Particularly high lateral forces can be absorbed by the
telescopic column in defined fashion, without generating
undesirable play of the arms, if an area with a larger radial
distance is provided on the outer and/or inner rod element between
laterally adjacent running surfaces for the at least one ball of
the at least one ball arrangement, in order to act as an abutment
for the ball in the manner of an overload protector. In the event
of lateral forces that induce deformation of the rod elements in
the area of the ball running surfaces, the ball can thus be caught
by an adjacent area previously not serving as a ball running
surface. The abutment area is preferably provided in the middle
between adjacent running surfaces and, when the ball is in its
intended position, preferably displays a distance from the ball
surface of 0.25 to 5%, more preferably 0.5 to 5%, particularly
preferably 1 to 2% of the ball diameter. Given a ball diameter of
10 mm, the radial distance between the abutment area and the ball
surface can thus preferably be 0.1 to 0.2 mm. This distance can
refer to the area of greatest depth of the abutment area or to the
outer edge area of the abutment. If appropriate, values other than
those mentioned can also be realized, depending on the necessary
lateral stability and the choice of material in each case.
[0020] The connecting line from the overload abutment area located
between adjacent ball running areas to the center point of the
respective ball preferably lies outside the circumference of the
subsequent ball in radial direction, so that the radially separated
ball guides are not directly affected even in the event of
deformation of a rod element in the area of the ball guide.
[0021] The telescopic column is preferably designed in such a way
that at least one rod element is made of a metal sheet or a section
of tubing, a groove in the form of an impression on the sheet or
tubing being provided on the rod element. This impression can be
produced, for example, by manufacturing the section of tubing by
the continuous casting method or by related production methods. It
is particularly advantageous to manufacture the rod element from
sheet metal by a rolling process with subsequent joining of the
longitudinal seam, making it possible to obtain particularly sharp
inner corners and rounded outer corners, which can represent
groove-limited edges, for example. The impression in the sheet or
section of tubing produces a corresponding protuberance on the
inside of the resultant rod element that can be designed, for
example, as a guide surface for an inside ball assigned to an inner
rod element. Particularly in the groove area, the rod element can
have the same material thickness as in the adjacent side wall areas
of the rod elements. The groove is preferably impressed in the
sheet metal or section of tubing in such a way that the groove-side
outer or inner surface of the rod element can be used directly, or
after only little machining, such as groove-like preforming of a
ball running surface, for assembly of the telescopic column.
[0022] The hollow-profile areas of the rod elements can, if
appropriate, display areas of different wall thickness distributed
around the circumference. In particular, greater wall thicknesses
can be realized in the area of the grooves than in adjacent areas.
The geometry of the interior of the hollow profile can thus differ
from the geometry of the outside of the hollow profile, where the
inner walls of the hollow profile can again be designed as guide
areas for running balls in this case. By designing the inner walls
of the hollow profile accordingly, it is possible for rod elements
of different geometry or of essentially identical geometry to be
rotated about their longitudinal axis and inserted into one
another, thereby by realizing ball guides.
[0023] The wall thickness of consecutive rod elements in radial
direction can increase in the radially inward direction, where, if
appropriate, consecutive rod elements can also display essentially
the same wall thickness.
[0024] The individual rod elements can each have several laterally
and/or axially separated guide areas that are assigned to a given
ball arrangement. In this context, several or all of the guide
areas can be provided with balls, or just a few of the guide areas
can be fitted with balls. In particular, the guide areas and the
rod elements that telescope relative to each other can be designed
in such a way that the rod elements can be rotated about their
longitudinal axes and inserted into each other in various positions
in order to obtain a telescopic column. With a given geometry of
the rod elements, the telescopic column can be adapted to various
demands on stability in this way. In this context, a ball
arrangement, which may also comprise a single ball, is taken to
mean an arrangement in which the balls within a given arrangement
are closer to each other than to an adjacent arrangement. The ball
arrangements can, in particular, each display several balls spaced
apart in the lateral and/or axial direction. Thus, groups of
laterally separated grooves can be located in the corners of
polygonal profiles or distributed around the circumference of the
rod elements, there being little or no space between the grooves
within the groups and a larger space between the groups. In
particular, separate grooves assigned to different side walls can
be located in a corner area of a polygonal profile.
[0025] A particularly advantageous configuration is obtained if at
least one ball, preferably at least one ball per rod element,
particularly preferably all the balls assigned to a rod element or,
in particular, all the balls of the telescopic column, display a
slight oversize referred to their target position in disassembled
condition of the telescopic column and make or impress running
grooves in at least one of the inner and outer rod elements that
telescope relative to each other by means of at least the first
telescoping movement, or possibly also a small number (for example
2 to 5, without being limited to this) of further telescoping
movements. Impression of the running grooves causes a plastic
deformation of the rod element material, the deformed region of the
rod element providing a running surface for the ball. In this way,
the running balls essentially create their own running surfaces,
this significantly facilitating the manufacture of the telescopic
column and affording it particularly high lateral and torsional
stability. During further telescoping movements, once the running
grooves have been impressed, a virtually constant frictional
resistance occurs during the telescoping movement. The ball
diameter of at least one ball or of a plurality of balls, and the
rod elements located inside and outside this ball in the radial
direction, which thus surround the ball, are advantageously
designed in such a way that the ball impresses its own running
tracks in both the inner and the outer rod element during the first
telescoping movement or after a small number of further telescoping
movements. During the running-in process, the respective ball
preferably impresses two or more running grooves in the inner or
outer rod element, particularly preferably in the inner and the
outer rod element, where the ball impresses at least one running
groove in the respective other rod element. Preferably, all the
balls of the telescopic column each impress at least two running
grooves in both rod elements to which they are assigned. This
characteristic is of special importance, particularly in connection
with grooves partially surrounding the balls, as the grooves
already provide defined guidance for the balls during their
running-in process. The above-mentioned configurations of the
telescopic columns with balls which impress their own running
grooves in the rod elements thus preferably each relate to a
telescopic column in which the respective ball or all the balls are
guided in guide grooves by the respectively assigned inner or outer
rod element, preferably by the inner and the outer rod element, so
that the running grooves are impressed into the inner and/or outer
guide grooves (also known as the longitudinal grooves). Hereby, at
least one, a plurality or all of the balls of corresponding inner
and outer rods may be surrounded by at least three walls, being
groove walls or side walls of the rods. Preferably, each rod
element displays more than two laterally separated impressed guide
grooves designed as described above, these preferably being located
in the corner areas of rod elements with polygonal cross-sectional
profiles, particularly preferably in diametrically opposite guide
grooves. Moreover, the above descriptions regarding the arrangement
of the ball running surfaces particularly also apply to running
surfaces impressed by the balls themselves.
[0026] In case the telescopic column comprises three telecopic rod
elements, some or all of the balls arranged between an outer and a
radial inwardly (middle) rod element and/or between the middle and
the radial inner rod element may be arranged in impressed running
surfaces.
[0027] The running-in movement of the balls is facilitated if the
running grooves are pre-machined in disassembled condition of the
telescopic column, i.e. if they do not display the definitive
geometry, particularly the groove depth, so that the definitive
running surfaces are created as a result of the oversize of the
running balls located between the rod elements.
[0028] Great stability of the telescopic column is obtained if at
least one or all of the inner rod elements essentially have a
polygonal profile and the at least one longitudinal groove is
provided in the corner area of at least one or all of the profiles.
Advantageously, all corner areas of one or all inner rod elements
are provided with corresponding guide grooves.
[0029] The grooves can be designed in such a way that one or both
of the adjacent lateral surfaces of the polygonal profile enclosing
the respective groove at least essentially point towards the center
point of the ball to be guided in the groove. As a result, the
balls can be supported particularly effectively by the adjacent
lateral surfaces of the polygonal profiles when exposed to lateral
forces. The ball running surfaces are advantageously located
directly adjacent to one or both of the adjacent lateral surfaces
of the polygonal profile.
[0030] Advantageously, all the rod elements of the telescopic
column essentially display a polygonal cross-section into which the
longitudinal grooves are incorporated. In this context, two, three
or more consecutive rod elements can essentially--apart from the
dimensioning required to permit insertion of the rod elements into
each other--display the same cross-sectional form. In particular,
consecutive rod elements or all the rod elements of a telescopic
column can display an equilateral or non-equilateral triangular,
rectangular, pentagonal and/or polygonal cross-section. The
cross-sections of the rod elements of a telescopic column can each
have the same or a different basic geometry. The guide grooves can
be located in all or some of the corner areas and/or in the middle
areas of the side walls of the polygonal rod elements.
[0031] Preferably, all the guide grooves of the rod elements are
fitted with running balls, or only some of the guide grooves if
appropriate. Preferably, at least two essentially opposite guide
grooves of the respective rod elements are fitted with running
balls.
[0032] In particular, the inner and outer walls of adjacent rod
elements can approach each other, essentially over the entire
circumference of the rod elements with the sole exception of the
longitudinal grooves for accommodating the corresponding balls, to
within a distance which corresponds roughly to the wall thickness
of the rod elements or is less than this or does not exceed two to
three times the wall thickness.
[0033] The ball arrangements of the telescopic columns according to
the invention can be designed to move in the longitudinal direction
relative to both rod elements, i.e. the respective outer and inner
rod elements, during telescoping movement, meaning that the balls
partially follow the movement when adjacent rod elements are
displaced relative to each other. The balls or ball arrangements
can, however, also be secured to prevent longitudinal displacement
in relation to one of the rod elements, or be of stationary
design.
[0034] For additional stabilization of the telescopic column, guide
elements that absorb forces acting laterally on the rod elements,
at least after slight angling of the rod elements relative to each
other, can be provided in the longitudinal direction of the rods,
above and/or below at least one ball arrangement on at least one
rod element, preferably above and/or below all the ball
arrangements on the respective rod element. The guide elements may
thus be at a certain lateral distance from the corresponding rod
element, so that the rod elements are guided exclusively on the
corresponding balls when only little or no lateral force is
exerted. The guide elements are preferably located at the ends of
the rod elements and preferably cap the ends, although they can
also be at a distance from the ends of the rod elements. The travel
of adjacent rod elements relative to each other can be limited by
the guide elements in one or both sliding directions, this
eliminating the need for separate travel limits stops.
[0035] It is particularly advantageous if at least one guide
element is provided that can be fixed in position on the respective
rod element by means of a snap-in connection, this snap-in
connection engaging at least one corner of the rod element designed
as a polygonal profile. Alternatively or in addition, the snap-in
connection can also be designed for fixing in position on the
respectively adjacent, radially outer rod element in the region of
a longitudinal groove. This makes the snap-in connection readily
accessible and it also has sufficient space. In particular, the
respective longitudinal groove can be provided in the corner area
of a polygonal profile. However, the snap-in connections can also
be provided at other suitable points. Advantageously, a
corresponding snap-in connection is provided at each of the corners
of a polygonal profile. In the case of profiles of a different
design, e.g. round profiles, a suitable number of snap-in
connections can be provided. The snap-in connections can be
designed for actuation from the outside of the rods.
[0036] The guide element described above can simultaneously be
designed as a face-end groove limiter. In particular, two guide
elements a distance apart can be assigned to one groove, so that
one or more balls are arranged in captive manner between the guide
elements. Furthermore, the ball retainer itself can retain the
ball(s) in captive manner, e.g. by providing a ball cage. However,
as an alternative, a ball guide with recirculating balls can also
be assigned to one or more of the grooves, particularly the
groove(s) immediately surrounded by the radially innermost rod
element, so that a ball removed from a groove during a telescoping
movement is returned to the groove at some other point.
[0037] The holders for the balls guided between adjacent rod
elements can be of a wide variety of designs. In particular, the
holders can, if necessary, be fixed in place on one of the
telescopic columns in a manner preventing displacement, if this is
required. The holders can also be designed to be essentially freely
displaceable over part or virtually all of the length of the rod
elements.
[0038] The ball retainers preferably display at least two or more
retaining areas, which can be assigned to laterally and/or axially
separated ball arrangements.
[0039] It is particularly advantageous if the retaining area, or
the two or more retaining areas, of a ball retainer are connected
to each other or to a main body by means of an articulated
connection, particularly in the form of an integral hinge. In this
way, the retaining areas can be angled in relation to each other
within the telescopic column and, owing to the articulated
connection, the ball retainer can be positioned essentially flat in
disassembled condition, this arrangement being particularly simple
to manufacture in a molding tool. In this context, different areas
of the ball retainer can lie at different levels relative to each
other. The ball retainer can, in particular, be made of a plastic
material and be produced by an appropriate manufacturing process,
such as an injection molding process.
[0040] In the case of polygonal rod elements, the ball retainers
can span one lateral surface of the same and jointly retain the
balls located in the circumferential direction of adjacent guide
grooves. The ball retainers each preferably span only one lateral
surface of rod elements having a polygonal profile, particularly
preferably respectively opposite lateral surfaces of a rod element,
where the ball retainers of the rod element located immediately
further inwards or outwards in the radial direction can be arranged
at a distance from the first ball retainers mentioned. Furthermore,
with this arrangement, several balls positioned axially one above
the other can be provided on at least one groove, preferably on all
grooves. The balls are preferably combined in groups of two or more
balls in the lateral and/or axial direction.
[0041] If three or more rod elements are provided, the ball
retainers for consecutive rod pairs in the radial direction can be
of identical or different design.
[0042] If the ball retainers span the groove areas of two of more
profile corners or laterally separated groove arrangements, which
are preferably adjacent to each other, the ball retainers for pairs
of consecutive rod elements can be congruent or staggered relative
to each other in the circumferential direction. A staggered layout
permits a particularly space-saving arrangement and thus maximum
cross-sections of the rod elements. The ball retainers are
advantageously provided on opposite sides of the rod elements.
[0043] An example of the invention is described below and explained
on the basis of the figures. The figures show the following:
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] FIG. 1 A cross-section of a telescopic column according to
the invention in retracted condition,
[0045] FIG. 2 A perspective view of a telescopic column according
to FIG. 1 in partially extended condition,
[0046] FIG. 3 A telescopic column according to FIG. 2 with guide
elements,
[0047] FIG. 4 A cross-section of a telescopic column according to
FIG. 1 with ball retainers,
[0048] FIG. 5 A detail view of the middle rod element according to
FIG. 2 with ball retainer,
[0049] FIG. 6 A detail view of the inner rod element according to
FIG. 2 with ball retainer, and
[0050] FIG. 7 A cross-section of a telescopic column according to
another embodiment according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0051] In the practical example illustrated in FIGS. 1 to 6,
telescopic column 1 consists of three rod elements 2, 3, 4, which
can be telescoped relative to each other and each have an
essentially rectangular cross-section. Radially outer rod elements
2 and 3 display roughly or exactly the same wall thickness, while
the wall thickness of inner rod element 4 is approx. 50% greater.
The corner areas of inner rod elements 3 and 4 display guide
grooves 5, 6 (see FIG. 2) which are open towards the outside, run
in the longitudinal direction of the rod elements, serve to
accommodate running balls 7, 8 and surround these over a
circumferential angle of approx. 90 degrees (radially outer running
ball 7) or approx. 70 degrees (radially inner running ball 8) on
the respective inner side. The axes connecting opposite ball
running surfaces enclose an angle of 70 degrees. Running balls 7, 8
are capable of moving relative to both adjacent rod elements (2 and
3 or 3 and 4) in the longitudinal direction of the rod
elements.
[0052] Radially outer running ball 7 is guided on outer rod element
2 on two running surfaces 9, which are a distance apart on the
circumference of the ball and enclose an angle of approx. 90
degrees. On the opposite side of the ball, a running surface is
provided for each of these running surfaces on the corresponding
guide groove. In this context, the running surface is located at
roughly the level of the adjacent side wall 10 of rod element 3,
which forms the narrower side wall of rod element 3, so that
laterally acting forces can be absorbed. A similar situation
applies to the two other radially outer and inner ball running
surfaces 9 and 11, which are opposite each other in relation to the
center point of the ball, where ball running surface 11 lies
essentially at the level of lateral surface 12, in this case at a
radial distance of roughly one wall thickness of the same.
[0053] Ball running surfaces 9 and 11 are each located roughly or
exactly at the level of the turning points or end-points of the
essentially linear sections of the adjacent side walls of the rod
elements or of areas 14 parallel to them.
[0054] With a ball diameter of approx. 10 mm, the width of the ball
running surfaces is approx. 1 to 2 mm. Ball running surfaces 9, 11
and 20, 21 are essentially worked into the rod elements by the
balls themselves during the first telescoping movement of the rod
elements relative to each other, where, during a preceding process
step, only running grooves 38 (FIG. 1) were incorporated into the
rod elements, their width being small compared to the width of the
definitive ball running surfaces, for instance 1/3 to 1/5 of the
same or less. Thus, the definitive running surfaces are formed
during the first telescoping movement, or the first few telescoping
movements, the direction of ball travel being defined by running
grooves 38 provided.
[0055] Ball running surfaces 20, 21 of the radially inner ball--the
same could also apply, at least facultatively, to balls lying
radially farther inwards--are located on a side wall 12 and on a
concave groove rear side 22 in relation to the outer rod element.
The same applies to the radially inner running surfaces of the same
ball on the inner rod element, where, instead of the side wall, a
section 14 running parallel to it is provided with a ball running
surface. In this context, the lines connecting radially separated
balls 7, 8, which are each assigned to different rod elements, are
located on a connecting line that does not pass through the
geometrical center point or the center of gravity of the rod
elements. The connecting line in the practical example includes a
smaller angle in relation to the side wall against which the balls
lie.
[0056] The same design principle can also be applied to triangular,
pentagonal or polygonal cross-sectional profiles or to curved, e.g.
round, oval or elliptical cross-sectional profiles. Thus, if a
further, inner rod element were to be provided, the further balls
would preferably be located in angular area 23, although location
in angular area 24 would, however, also be possible, in which case
the balls of the radially separated rod elements would then not lie
on a straight or essentially straight line.
[0057] According to the practical example with groups of two
radially separated balls 7, 8 each, three ball running surfaces lie
on an at least essentially straight line V1. According to the
practical example, this line runs between the diagonal and the side
walls of the rod elements. It is also possible for more than three
ball running surfaces to lie on one line, particularly if more than
two radially inner rod elements 3, 4 are provided. The ball running
surfaces lying on a line can be the immediately consecutive ones in
the radial direction, as in the practical example, although, if
appropriate, ball running surfaces can be provided between these,
whose position deviates substantially from the straight line. This
deviation can also apply to the radially innermost and/or outermost
ball running surfaces in each case, preferably only to these.
According to the practical example, the deviation of the ball
running surfaces from the straight line is approx. 1/4 to 1/5 of
the ball diameter or less, without being limited to this.
[0058] Provided between adjacent running surfaces assigned to a
ball are rod areas 15, 16, 17, which are at a slightly larger
radial distance from the balls, so that a gap arises between the
ball and the rod area. The gap depth according to the practical
example is approx. 0.1 to 0.2 mm. If the rod elements are deformed
in the area of the ball guides, these areas 15 to 17 can support
the ball and form additional running surfaces. The overload
abutments are preferably located radially inwards relative to the
ball, or alternatively or additionally radially outwards relative
to the ball, if appropriate, and lie roughly on connecting line V2
between the respective corner of the idealized profile of the rod
element and its center point. The deviation from the straight line
is preferably 1/4 to 1/5 or less of the ball diameter, without
being limited to this. The deviation mentioned can apply to some or
all of the overload areas.
[0059] The rod elements are manufactured from sheet metal material
by means of a rolling process with subsequent formation of a weld
seam, which runs in the longitudinal direction of the rod element
and can be provided in the side area. The rolling process makes it
particularly easy to incorporate the grooves, where inner shaping
angles 18 can be made to be particularly sharp, while outer shaping
angles 19 are rounded. At the same time, this also makes it
possible to manufacture ball guide grooves 5, 6 with sufficient
accuracy.
[0060] FIG. 3 shows a telescopic column with guide elements 25,
which are fitted onto or inserted into the face ends of the rod
elements and can be fixed in position by means of snap-in
connections provided in the corner areas. The snap-in connections
can be released from the outside via slits in the rod elements. In
this context, the snap-in tabs of the snap-in connections are
located at the level of the ball guide grooves, so that the snap-in
tabs have sufficient play. This permits simple fastening of the
guide elements if, over virtually the entire circumference,
essentially only with the exception of the areas of the ball guide
grooves, the inner and outer walls of adjacent rod elements are
only separated by a small distance that is essentially in the
region of the wall thickness of the rod elements, for instance in
the region of once to twice the wall thickness, or even less.
[0061] Supplementary to FIG. 1, FIG. 4 shows ball retainers 27,
which each jointly retain ball arrangements of adjacent corner
areas of the rod elements and span the respective side walls for
this purpose. The ball retainers display conventional ball cages 28
and intermediate connecting pieces 29, these being interconnected
via articulated connections 30 in the style of integral hinges.
Thus, when in disassembled condition, ball cages 28 can be swung
essentially into the plane of connecting piece 29 or into a
parallel plane, this greatly facilitating the manufacture of the
ball retainers, which can be made of a plastic material. Ball
retainers 27 and 31 are assigned in pairs to opposite lateral
surfaces of rod elements 3 and 4 and are arranged in staggered
fashion in the circumferential direction of the rod elements or
arranged with gaps between them. It goes without saying that,
particularly also in the case of other cross-sectional geometries
of the rod elements, ball retainers 27 and 31 can be assigned to
several or just one guide groove or guide groove arrangement with
several immediately adjacent guide grooves.
[0062] FIGS. 5 and 6 show rod elements 3, 4 with the respective
ball retainers 27, 31.
[0063] Ball retainers 27 and 31 each display axially separated
retaining areas 33 and 34, which are each assigned to adjacent
corners of the polygonal profiles. Ball arrangements 35 each
display two axially separated balls 37, one behind the other in the
longitudinal direction of the rod element. In this context, main
piece 29 extends over a relatively great axial length of the
respective rod element, roughly over once to twice the transverse
extension of the longer cross-sectional axis of the inner or outer
rod element. In this context, retaining areas 33 themselves extend
only slightly more over the respective ball circumference, meaning
that the axially and laterally separated retaining areas can be
pivoted independently of each other relative to connecting area
33.
[0064] FIG. 7 shows a section of a further telescopic column
according to the present invention having inner and outer rod
elements 40, 41. The inner rod element 40 is provided with a
guiding longitudinal groove 46 and a ball 42 being in engaging
contact with a side wall 44 of the outer rod element. The diameter
of the ball is chosen so that it makes two running surfaces in the
inner rod element and one running surface in the outer rod element
at least during the first telescopic movement. It is obvious for
someone skilled in the art that rod element may be designed so that
the ball is positioned between two walls of a groove of the outer
rod element and one side wall of the inner rod element, so that
during the at least first telescopic movement two running surfaces
are made in the outer rod element and one running surface is made
in the inner side element. In both embodiments two running surfaces
44 are made in opposite walls of one groove.
* * * * *