U.S. patent application number 13/510012 was filed with the patent office on 2012-09-06 for positioning device for converting a rotary motion into a linear motion.
This patent application is currently assigned to Pierburg GmbH. Invention is credited to Andreas Koester, Martin Nowak, Andres Toennesmann.
Application Number | 20120222507 13/510012 |
Document ID | / |
Family ID | 43733871 |
Filed Date | 2012-09-06 |
United States Patent
Application |
20120222507 |
Kind Code |
A1 |
Toennesmann; Andres ; et
al. |
September 6, 2012 |
POSITIONING DEVICE FOR CONVERTING A ROTARY MOTION INTO A LINEAR
MOTION
Abstract
A positioning device for converting a rotary motion into a
linear motion includes a drive unit configured to generate a
torque, a drive shaft on which an eccentric is arranged, a coupling
element comprising a slot, an output shaft arranged at the
eccentric. The output shaft is configured to move in the slot of
the coupling element. An adjusting element is connected with the
coupling element. The adjusting element is supported so as to be
linearly movable with the coupling element. The slot comprises a
guide path configured to cooperate with the eccentric which
comprises an angle with a plane perpendicular to a direction of
movement of the adjusting element.
Inventors: |
Toennesmann; Andres;
(Aachen, DE) ; Nowak; Martin; (Leverkusen, DE)
; Koester; Andreas; (Essen, DE) |
Assignee: |
Pierburg GmbH
Neuss
DE
|
Family ID: |
43733871 |
Appl. No.: |
13/510012 |
Filed: |
November 2, 2010 |
PCT Filed: |
November 2, 2010 |
PCT NO: |
PCT/EP10/66613 |
371 Date: |
May 16, 2012 |
Current U.S.
Class: |
74/55 |
Current CPC
Class: |
Y02T 10/144 20130101;
F02B 37/186 20130101; Y02T 10/12 20130101; F02M 26/54 20160201;
F16K 31/528 20130101; F02B 39/00 20130101; Y10T 74/18296 20150115;
F02M 26/67 20160201; Y10T 74/18208 20150115 |
Class at
Publication: |
74/55 |
International
Class: |
F16H 25/08 20060101
F16H025/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2009 |
DE |
10 2009 053 428.8 |
Claims
1-6. (canceled)
7. A positioning device for converting a rotary motion into a
linear motion, the positioning device comprising: a drive unit
configured to generate a torque; a drive shaft on which an
eccentric is arranged; a coupling element comprising a slot; an
output shaft arranged at the eccentric, the output shaft being
configured to move in the slot of the coupling element; and an
adjusting element connected with the coupling element, the
adjusting element being supported so as to be linearly movable with
the coupling element, wherein, the slot comprises a guide path
configured to cooperate with the eccentric which comprises an angle
with a plane perpendicular to a direction of movement of the
adjusting element.
8. The positioning device as recited in claim 7, wherein the guide
path is a curve with a changing slope.
9. The positioning device as recited in claim 7, further comprising
a roller or a bearing arranged on the output shaft, wherein the
roller or bearing is configured to move in the slot.
10. The positioning device as recited in claim 7, wherein an
initial position of a rotation for an actuation of the adjusting
element is a position that is located, seen in a direction of
rotation, before a dead center existing for an axial movement of
the output shaft, the dead center being passed during a rotational
movement to an end position.
11. The positioning device as recited in claim 10, further
including a first part of the slot to be travelled by the output
shaft and a second part of the slot to be travelled by the output
shaft, wherein the first part of the slot to be traveled by the
output shaft has an ascending slope with respect to a plane
vertical with respect to a direction of movement of the adjusting
element, and the second part of the slot to be traveled by the
output shaft has a descending slope with respect to the plane
vertical with respect to the direction of movement of the adjusting
element.
12. The positioning device as recited in claim 11, further
including a circular arc with a slope, wherein the ascending slope
in the first part of the slot to be traveled by the output shaft is
steeper than the slope of the circular arc when the output shaft
travels from a first end portion to a top dead center of the axial
movement.
Description
CROSS REFERENCE TO PRIOR APPLICATIONS
[0001] This application is a U.S. National Phase application under
35 U.S.C. .sctn.371 of International Application No.
PCT/EP2010/066613, filed on Nov. 2, 2010 and which claims benefit
to German Patent Application No. 10 2009 053 428.8, filed on Nov.
19, 2009. The International Application was published in German on
May 26, 2011 as WO 2011/061051 A1 under PCT Article 21(2).
FIELD
[0002] The present invention provides a positioning device for
converting a rotary motion into a linear motion comprising a drive
unit generating a torque, a drive shaft on which an eccentric is
arranged, an output shaft arranged at the eccentric and movable in
a slot of a coupling member, and an adjusting element connected
with the coupling element and supported so that the adjusting
element is adapted to be moved linearly together with the coupling
element.
BACKGROUND
[0003] Such positioning devices are used in particular to drive
exhaust gas recirculation valves, but they may also be used in
waste gate valves, butterfly valves or as VNT actuators.
[0004] Various valves with positioning devices or similar
positioning devices are known, wherein an electric motor serves as
the drive unit whose drive shaft is coupled with eccentrics of
various types, the motion of the eccentrics being converted, via
different coupling mechanisms, into a linear motion of a valve rod
serving as an adjusting element.
[0005] EP 1 319 879 A1 describes a valve driven by an electric
motor, wherein an output shaft is arranged eccentrically with
respect to a drive shaft, a roller being provided rotatably on the
output shaft and traveling in a slot of a coupling element. The
roller is spring-biased in one direction. The traveling path of the
coupling element slot provided for the roller is perpendicular to
the direction of movement of the coupling element. The development
of the force-stroke curve of this element is thus fixed.
[0006] DE 102 21 711 A1 describes a similar valve wherein two
eccentrics are coupled with each other. In this design, the slot
that serves as a traveling path for a ball bearing is also designed
as a straight line that extends perpendicularly to the direction of
movement. It is again not possible to provide special required
force-stroke curves during the actuation of the valve with
sufficient variability.
[0007] A valve driven by an electric motor is also described in EP
1 378 655 A2, wherein a rotating member comprises two opposite
slots in which a rod is guided which in turn is connected with a
valve rod. The slot may here be configured as a defined curve. With
this design, it is possible to set a defined effort for the
adjustment of the valve as a direct function of the stroke. The
required structural space is rather large, as is the number of
components needed.
SUMMARY
[0008] An aspect of the present invention is to provide a
positioning device which allows the selection of a force-stroke
curve or a rotational angle-stroke curve for specific applications
and which at the same time requires as little space as
possible.
[0009] In an embodiment, the present invention provides a
positioning device for converting a rotary motion into a linear
motion which includes a drive unit configured to generate a torque,
a drive shaft on which an eccentric is arranged, a coupling element
comprising a slot, an output shaft arranged at the eccentric. The
output shaft is configured to move in the slot of the coupling
element. An adjusting element is connected with the coupling
element. The adjusting element is supported so as to be linearly
movable with the coupling element. The slot comprises a guide path
configured to cooperate with the eccentric which comprises an angle
with a plane perpendicular to a direction of movement of the
adjusting element. Due of the previously unknown interaction of an
eccentric drive and a slot curve path, it is possible for the first
time, and to a much larger extent than before, to set force-stroke
curves rotational angle-stroke curves that allow for an adjustment
of such a positioning device to a number of different applications.
The structural space is thereby not larger than with other known
eccentric drives. With the same total stroke, the length of the
eccentric may be chosen to be even smaller.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention is described in greater detail below
on the basis of embodiments and of the drawings in which:
[0011] FIG. 1 shows a perspective view of the coupling device and
the eccentric of a positioning device according to prior art;
[0012] FIGS. 2a) and b) shows the coupling device and the eccentric
of a positioning device of the present invention at the respective
end positions;
[0013] FIG. 3 shows the function of linear stroke over an angle of
rotation for a positioning device with a coupling device of FIG. 2
in graphic representation; and
[0014] FIG. 4 shows the function of force over stroke for a
positioning device with a coupling device of FIG. 2 in a graphic
representation, compared with the corresponding function of a plane
slot.
DETAILED DESCRIPTION
[0015] In an embodiment of the present invention, the slot can, for
example, describe a curve with a varying pitch. This provides
additional possibilities for the adjustment of force-stroke curves
to specific applications.
[0016] In an embodiment of the present invention, a roller or a
bearing can, for example, be arranged on the output shaft, which
travels in the slot so that friction between the slot or its
traveling path and the outer path of the rolling body, i.e. the
bearing or the roller in the present instance, is minimized.
[0017] In an embodiment of the present invention, the initial
position of the rotation for the actuation of the adjusting element
can, for example, be a position which, seen in the direction of
rotation, is situated before a dead center existing for the axial
movement of the output shaft, which dead center is passed during
the rotational movement to the end position. It thus becomes
possible to realize short strokes of a valve with rather large
actuating angles, which allows for an exact proportioning in the
sensitive adjustment range shortly after leaving the closed
position.
[0018] In an embodiment of the present invention, a first portion
of the slot to be traveled by the output shaft can, for example,
have an upward slope with respect to the plane perpendicular to the
direction of movement of the adjusting element, while a second
portion to be traveled can, for example, have a downward slope.
With such a design, a further adaptation of the relationship
between the angle of rotation and the resulting stroke can be
obtained as well as an adaptation to a desired force-stroke
characteristic which may lead, for example, to a largely constant
effort for the adjustment in the first portion. At the same time,
such an adaptation allows for an additional reduction outside an
upstream transmission.
[0019] In an embodiment of the present invention, the upward slope
in the first portion to be traveled can, for example, be steeper
than the upward slope of a rolling line of the output shaft when
traveling through the portion from a first end position to the top
dead center, seen with respect to the axial movement of the output
shaft. It is thereby provided that a stroke occurs in this
adjustment region.
[0020] The can thus be kept constant in a significant region about
at least one of the two end stops. The available adjustment force
thereby becomes independent of tolerances that could occur, for
example, as a result of a thermal expansion of the valve rod. Such
an almost constant force curve in the region of the closed position
for about 15-25% of the full stroke is required in particular in
case of the application of the positioning device as an actuator of
a waste gate valve, because of the prevailing gas pressure forces
at the gate.
[0021] A positioning device is thus provided whose coupling device,
in combination with the eccentric, leads to the possibility of a
selectable force-stroke setting by appropriately adjusting the
selected rotational angle range with respect to the slot. The
present positioning device also allows an adjustment between the
angle of rotation and the stroke for a better proportioning. The
required structural space is at the same time kept very small.
[0022] An embodiment of the positioning device of the present
invention is illustrated in the drawings and will hereinafter be
described.
[0023] FIG. 1 illustrates a detail of a positioning device
corresponding to the prior art. The part here illustrated is the
part of the positioning device essential to the present
invention.
[0024] As is known per se, the positioning device comprises a
non-illustrated rotary drive unit such as, for example, an electric
motor, which drives a drive shaft 2. On the end of the drive shaft
2 opposite the drive unit, an eccentric 4 is provided in a manner
secured against rotation. At the end of the eccentric 4 remote from
the drive shaft 2, an output shaft 6 is provided that extends
parallel to the drive shaft 2 so that the output shaft 6 rotates in
a circular manner about the drive shaft 2 when the drive shaft 2 is
rotated.
[0025] A ball bearing 8 is arranged at the end of the output shaft
6 opposite the eccentric 4, the inner race thereof being fastened
on the output shaft 6. An outer race 10 of the ball bearing 8 moves
in a slot 12 of a coupling element 14 to which an adjusting element
16 in the form of a valve rod of a globe valve not illustrated in
detail herein. The valve rod is supported in a housing in a manner
known per se so that it can only perform a linear stroke movement
with the coupling element. In the coupling device 14 illustrated,
the slot 12 is an opening limited in height by two limiting walls
17, 18 whose mutual distance substantially corresponds to the
circumference of the ball bearing 8 and whose width is determined
by the length of the eccentric 4 and by the adjustment angle
thereof. The limiting walls 17, 18 that serve as the guide path 20
of the ball bearing 8 are designed as straight planes that extend
perpendicularly to the direction of movement of the valve rod 8
when the drive unit is operated.
[0026] In comparison with the above, the slot 12 according to the
present invention, or the resulting guide track 20, illustrated in
FIG. 2 is designed as a curve. A curve in the sense of the present
application is thus a line that is not necessarily completely
linear.
[0027] This curve is designed so that a positioning device of this
type is suitable, for example, to drive a waste gate valve. With
such a valve, it is desired that, when leaving the closed position
of the valve, the valve force remains approximately constant over a
certain opening range.
[0028] In FIG. 2, the eccentric 4 is only indicated as a connecting
line between the fulcrum of the eccentric 4 and the pivot point 6
of the bearing 8 or a roller. FIG. 2a) illustrates the coupling
element 14 in a position in which the adjusting element 16 is in a
first end position that is defined, for example, by correspondingly
formed stops for upstream gears or other movable parts. In this
position, the bearing 8 is located at the left end of the slot 12
below a dead center 24 of the eccentric 4 that is the top dead
center with respect to the axial movement of the pivot point 6.
[0029] If, hereafter, the drive unit is operated clockwise and the
eccentric is thereby rotated clockwise, the bearing 8 is rotated at
a constant distance around the rotational axis of the drive shaft 2
and rolls along the guide path 20 of the slot 12 that is only
movable in the vertical direction. A first part of the slot 12
travelled by the rolling of the bearing 8 has a slope 22 with
respect to a plane vertical to the actuation direction of the
adjusting element, which slope is steeper than the respective
circular arc traveled by the bearing. Despite the upward movement
of the be aring, this causes a downward movement of the slot 12 and
thus of the coupling element 14 and the adjusting element 16. The
part of the guide path 20 following after the top dead center 24
has been passed first has a lesser upward slope 22 that eventually
passes into a downward slope in a second part 26. FIG. 2b)
illustrates the second end position reached after both parts 22, 26
have been passed.
[0030] The stroke resulting from this movement is plotted in FIG. 3
over the rotational angle. It is evident that the resulting graph
28 is rather flat in the first part and is significantly steeper as
the stroke becomes larger. Such a curve is advantageous, since it
is drastically facilitates volume flow control, because in the part
just after opening a small change in the stroke results in a rather
significant change in the volume flow, whereas, with a rather large
stroke, a change in stroke only results in rather small changes in
the volume flow.
[0031] In FIG. 4 the graph 30 illustrates the force-stroke curve of
a positioning device according to FIG. 2, whereas the dotted graph
32 represents the force-stroke curve of a positioning device with a
guide path perpendicular to the movement direction of the adjusting
element as illustrated in FIG. 1. In a range of up to about 4 mm of
stroke, corresponding to about 25% of the total stroke, the valve
force to be applied by a positioning device of FIG. 2, contrary to
the valve force to be applied by a positioning device of FIG. 1,
only changes slightly with the stroke.
[0032] Besides this advantage of setting a desired force curve, it
is also possible to realize additional reductions and transmissions
with respect to the entire adjustment range by using the slot to
increase or reduce the adjusting path of the adjusting element
relative to the length of stroke of the output shaft.
[0033] Additional structural space can be saved in this manner. The
positioning device of the present invention allows adjusting both
force-stroke curves and rotational angle-stroke curves depending on
the respective application, so that such a positioning device can
be used in many different applications, basically without resulting
in a larger required structural space as compared with known
positioning devices.
[0034] The scope of protection of the claims is not restricted to
the embodiment described, different forms of the guide path may be
desired depending on the application, in order to achieve the
advantageous force-stroke curve. It is also possible to design such
a positioning device to act in the opposite direction.
* * * * *