U.S. patent number RE33,863 [Application Number 07/136,027] was granted by the patent office on 1992-03-31 for actuator for control valves and related systems.
This patent grant is currently assigned to Paradygm Science and Technologies, Inc.. Invention is credited to Ronald R. Bowman, Ingvar E. Sodal.
United States Patent |
RE33,863 |
Bowman , et al. |
March 31, 1992 |
Actuator for control valves and related systems
Abstract
An actuator system is provided which includes a force transfer
element and a force receiving element. A viscous material
interconnects the force transfer element and the force receiving
element. A workpiece, such as a valve member, is connected to the
force receiving element. When a controlled force is applied to the
force transfer element, the controlled force and resulting movement
are rigidly coupled using the viscous material to the force
receiving element so that the workpiece can be moved or otherwise
operably controlled. When an uncontrolled force is received by the
force transfer element, in which the movement of the force transfer
element is slow relative to the deformation of the viscous
material, there is no coupling of the uncontrolled force and
resulting movement to the workpiece. As a result, the actuator
system is able to couple rapid movements using the viscous
material, while relatively slow movements are not coupled.
Uncontrolled forces contemplated by this invention include forces
resulting from stress, aging drift, and temperature variations
associated with the force transfer element and the force receiving
element.
Inventors: |
Bowman; Ronald R. (Boulder,
CO), Sodal; Ingvar E. (Boulder, CO) |
Assignee: |
Paradygm Science and Technologies,
Inc. (Boulder, CO)
|
Family
ID: |
26833917 |
Appl.
No.: |
07/136,027 |
Filed: |
December 21, 1987 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
564415 |
Dec 22, 1983 |
04560871 |
Dec 24, 1985 |
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Current U.S.
Class: |
250/288;
251/57 |
Current CPC
Class: |
F16K
31/007 (20130101) |
Current International
Class: |
F16K
31/00 (20060101); B01D 059/44 () |
Field of
Search: |
;250/281,288,289
;251/57 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1179481 |
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May 1959 |
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FR |
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2425599 |
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Jan 1980 |
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FR |
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489216 |
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Jul 1938 |
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GB |
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1410312 |
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Jan 1974 |
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GB |
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Primary Examiner: Anderson; Bruce C.
Attorney, Agent or Firm: Sheridan, Ross & McIntosh
Claims
What is claimed is:
1. A method for controlling the operation of a .[.workpiece.].
.Iadd.valve system that includes a portion of a mass spectrometer,
.Iaddend.comprising:
.Iadd.providing a force transfer element;
providing a force receiving element;
defining a gap between said force transfer element and said force
receiving element; .Iaddend.
delivering a force to .[.a.]. .Iadd.said .Iaddend.force transfer
element;
transferring at least a portion of said force to viscous means
using said force transfer element.Iadd., said viscous means
substantially filling said gap and being substantially free of
non-fluid material.Iaddend.;
rigidly coupling at least a portion of said force to .[.a.].
.Iadd.said .Iaddend.force receiving element using said viscous
means;
causing said force receiving element to react when at least a
portion of said force is received by said force receiving
element;
transferring at least a portion of said force from said force
receiving element to a .[.workpiece.]. .Iadd.valve
system.Iaddend.;
controlling the operation of said .[.workpiece.]. .Iadd.valve
system .Iaddend.using the reaction of said force receiving
element.Iadd., wherein said controlling step includes controlling
the flow of fluid into an ionization chamber of a mass spectrometer
using said valve system.Iaddend.;
decoupling using said viscous means one of said force transfer
element and said force receiving element when an unwanted force is
applied to one of said force transfer element and said force
receiving element; and
maintaining said .[.workpiece.]. .Iadd.valve system .Iaddend.in the
same state during said decoupling step.
2. A method, as claimed in claim 1, wherein:
said transferring step includes moving said force transfer element
to transfer at least a portion of said force to said viscous
means.
3. A method, as claimed in claim 1, wherein:
said unwanted force includes a force due to at least one of the
following: stress, aging drift, and temperature variations which
are associated with said force transfer element and/or said force
receiving element.
4. A method, as claimed in claim 1, wherein:
said maintaining step includes keeping said .[.workpiece.].
.Iadd.valve system .Iaddend.in substantially the same position
occupied by said .[.workpiece.]. .Iadd.valve system
.Iaddend.immediately before said decoupling step.
5. A method for controlling the operation of a workpiece,
comprising:
.Iadd.providing a force transfer element;
.Iadd.providing a force receiving element;
.Iadd.defining a gap between said force transfer element and said
force receiving element; .Iaddend.
delivering a controlled force to .[.a.]. .Iadd.said .Iaddend.force
transfer element;
transferring at least a portion of said controlled force to viscous
means using said force transfer element.Iadd., said viscous means
substantially filling said gap and being substantially free of
non-fluid material.Iaddend.;
rigidly coupling at least a portion of said controlled force to
.[.a.]. .Iadd.said .Iaddend.force receiving element using said
viscous means.Iadd., said coupling step including using surface
tension of said viscous means to substantially contain said viscous
means in a desired location.Iaddend.;
causing said force receiving element to react when at least a
portion of said controlled force is received by said force
receiving element;
transferring at least a portion of said controlled force from said
force receiving element to a workpiece;
controlling the operation of said workpiece using the reaction of
said force receiving element; and
preventing the transfer using said viscous means to said workpiece
of a non-controlled force and movement resulting from said
non-controlled force.
6. A method, as claimed in claim 5, wherein:
said workpiece includes a valve and said controlling step includes
regulating the opening and closing of said valve.
7. A method, as claimed in claim 5, wherein:
said step of causing said force receiving element to react includes
moving said force receiving element.
8. A method, as claimed in claim 5, wherein:
said step of preventing includes locating said viscous means in a
space that is free of a fixed barrier along at least one portion of
said viscous means. .[.9. A method, as claimed in claim 5,
wherein:
said step of coupling includes using surface tension of said
viscous means
to substantially contain said viscous means in a desired
location..]. 10. A method, as claimed in claim 5, wherein:
said preventing step occurs when the movement of said force
transfer element is slow relative to the time of deformation of
said viscous means.
1. A method, as claimed in claim 5, wherein:
said non-controlled force includes a force generated because of at
least one of the following: stress, aging drift, and temperature
variations, which are associated with said force transfer element
and/or said force
receiving element. 12. A method, as claimed in claim 5,
wherein:
said controlling step includes moving said workpiece to a desired
position.
3. An apparatus for controlling the operation of a .[.reacting
member.]..Iadd.valve system that includes a portion of a mass
spectrometer.Iaddend., comprising:
a force transfer element for receiving a controlled force;
a force receiving element in operative association with said force
transfer element;
.Iadd.a gap defined between said force transfer element and said
force receiving element;
.Iadd.viscous means substantially filling said gap and being
substantially free of non-fluid material; .Iaddend.
.Iadd.said .Iaddend.viscous means connecting said force transfer
element and said force receiving element together for rigidly
coupling at least a portion of said controlled force from said
force transfer element to said force receiving element;
a .[.workpiece.]. .Iadd.valve system including a portion of a mass
spectrometer .Iaddend.operatively associated with said force
receiving element, the operation of said .[.workpiece.].
.Iadd.valve system .Iaddend.being controlled by said force
receiving element using at least a portion of said controlled
force.Iadd., said valve system controlling the flow of fluid into
an ionization chamber of a mass spectrometer.Iaddend.; and
said viscous means being located in .[.a space.]. .Iadd.said gap
.Iaddend.in which movement of said viscous means due to a
non-controlled force is permitted but said movement is less than
the movement necessary to cause a transfer of said non-controlled
force and movement resulting from said non-controlled force to said
.[.workpiece.]. .Iadd.valve
system.Iaddend.. 14. An apparatus.[., as claimed in claim 13,
wherein.]. .Iadd.for controlling the operation of a reacting
member, comprising:
a force transfer element for receiving a controlled force;
a force receiving element in operative association with said force
transfer element;
a gap defined between said force transfer element and said force
receiving element;
viscous means substantially filling said gap and being
substantially free of non-fluid material, .Iaddend.said viscous
means .[.is.]. .Iadd.being .Iaddend.open to the ambient.Iadd.;
said viscous means connecting said force transfer element and said
force receiving element together for rigidly coupling at least a
portion of said controlled force from said force transfer element
to said force receiving element;
a workpiece operatively associated with said force receiving
element, the operation of said workpiece being controlled by said
force receiving element using at least a portion of said controlled
force; and
said viscous means being located in said gap in which movement of
said viscous means due to a non-controlled force is permitted but
said movement is less than the movement necessary to cause a
transfer of said non-controlled force and movement resulting from
said non-controlled force
to said workpiece..Iaddend. 15. An apparatus.[., as claimed in
claim 13, wherein.]. .Iadd.for controlling the operation of a
reacting member, comprising:
a force transfer element for receiving a controlled force;
a force receiving element in operative association with said force
transfer element;
a gap defined between said force transfer element and said force
receiving element;
viscous means substantially filling said gap and being
substantially free of non-fluid material, .Iaddend.each of said
force transfer element and said force receiving element has a
number of surfaces including a contacting surface each of which
contacts said viscous means, and wherein substantially all of said
viscous means contacts said contacting surfaces and substantially
none of said viscous means contacts the other surfaces of said
force transfer element and said force receiving element.Iadd., said
gap being located between said contacting surfaces of said force
transfer element and said force receiving element;
said viscous means connecting said force transfer element and said
force receiving element together for rigidly coupling at least a
portion of said controlled force from said force transfer element
to said force receiving element;
a workpiece operatively associated with said force receiving
element, the operation of said workpiece being controlled by said
force receiving element using at least a portion of said controlled
force; and
said viscous means being located in said gap in which movement of
said viscous means due to a non-controlled force is permitted but
said movement is less than the movement necessary to cause a
transfer of said non-controlled force and movement resulting from
said non-controlled force
to said workpiece..Iaddend. 16. An apparatus, as claimed in claim
13, further including:
means for providing said controlled force. 17. An apparatus, as
claimed in claim 16, wherein:
said means for providing a controlled force includes a
piezoelectric device. .[.18. An apparatus, as claimed in claim 13,
wherein:
said workpiece includes a valve system..]. .[.19. An apparatus, as
claimed in claim 18, wherein:
said valve system includes a portion of a mass spectrometer which
controls the flow of fluids into an ionization chamber of said mass
spectrometer..]. .Iadd.20. An apparatus for controlling the
operation of a reacting member, comprising:
a force transfer element for receiving a controlled force;
a force receiving element in operative association with said force
transfer element;
a space between said force transfer element and said force
receiving element;
viscous means connecting said force transfer element and said force
receiving element together for rigidly coupling at least a portion
of said controlled force from said force transfer element to said
force receiving element, said viscous means having surface tension
wherein said surface tension of said viscous means is used to
substantially contain said viscous means in a desired location;
a workpiece operatively associated with said force receiving
element, the operation of said workpiece being controlled by said
force receiving element using at least a portion of said controlled
force; and
said viscous means being located in said space in which movement of
said viscous means due to a non-controlled force is permitted but
said movement is less than the movement necessary to cause a
transfer of said non-controlled force and movement resulting from
said non-controlled force
to said workpiece..Iaddend. .Iadd.21. An apparatus for controlling
the operation of a reacting member, comprising:
a force transfer element for receiving a controlled force, said
force transfer element having a number of surfaces including at
least one contacting surface;
a force receiving element in operative association with said force
transfer element, said force receiving element having a number of
surfaces including at least one contacting surface;
a space between said force transfer element and said force
receiving element, said space being located between said contacting
surfaces of said force transfer element and said force receiving
element;
viscous means connecting said force transfer element and said force
receiving element together for rigidly coupling at least a portion
of said controlled force from said force transfer element to said
force receiving element, substantially all of said viscous means
contacting said contacting surface of said force transfer element
and said force receiving element and substantially none of said
viscous means contacting the other surfaces of said force transfer
element and said force receiving element;
a workpiece operatively associated with said force receiving
element, the operation of said workpiece being controlled by said
force receiving element using at least a portion of said controlled
force; and
said viscous means being located in said space in which movement of
said viscous means due to a non-controlled force is permitted but
said movement is less than the movement necessary to cause a
transfer of said non-controlled force and movement resulting from
said non-controlled force to said workpiece..Iaddend.
Description
FIELD OF THE INVENTION
This invention relates to an actuator system for a fluid handling
control valve system and to methods and systems for using such
actuator and valves. More particularly it relates to a stable valve
system for controlling the flow of fluids through an opening, which
valve system is activated by and in response to controlled rapid
actuation, but which is not responsive to slow uncontrolled
movement or random actuation.
BACKGROUND OF THE INVENTION
Specialized small valve systems have been developed to control
fluid flow to evacuated chambers such as those used with mass
spectrometers, vacuum evaporation and coating systems, epitaxial
deposition systems, plasma etching installations, ion milling,
sputtering systems, ion implantation, gas mixing and the like. Such
valve systems have had to meet the special demands of being capable
of controlling fluid flow between areas having immense pressure
differentials. Additionally, they have usually had to meet the
requirements of having very precise actuator mechanisms, or of
being very small, or of being both very precise and very small.
Efforts to teach gas flow control systems, actuators and valves of
this kind, which are especially suited for use with mass
spectrometers, are set forth in U.S. Pat. No. 3,895,231 and is
divisional U.S. Pat. Nos. 3,926,209 and 4,018,241. These references
disclose systems in which fluid flow to an evacuated chamber, and
especially in mass spectrometers, is controlled by utilizing a
valve in which a tapered needle is positionally adjusted with
respect to an inlet opening or valve seat by a piezoelectric
ceramic actuator on which the needle is mounted. The piezoelectric
ceramic actuator is flexed by the application of electric potential
(voltage). In the systems taught by the above U.S. patents,
servo-control systems provide for the selection of the amount of
electric potential, which in turn controls the amount of
piezoelectric ceramic flexing, and the concommitant movement of the
valve needle for the valve seat, and therefore the volume of fluid
which can flow through the valve. In those systems, the
servo-control systems taught are responsive to some condition, such
as pressure, within the chamber into which the fluid is being
injected.
In practice, such valve systems have usually required quite small
openings, say 0.05 microns or less in diameter, and the valve stem
movements have been in the micrometer and nanometer range. In such
applications, due to the small sizes and tolerances of such valve
systems, and also to the nature and character of the piezoelectric
actuator, such valve systems have been difficult to construct
accurately. Once constructed such valve systems have been difficult
to maintain. More specifically, in order to reliably provide
precise small valve movements of, for example, one micrometer or
less by conventional means requires tolerances in the machining and
in the assembly of the valve parts which are extremely difficult to
obtain. Additionally, at such small dimensions, even with almost
perfect machining and assembly, after construction of such a valve,
drifts can occur in the piezoelectric actuator, stem, or other
components of the system such that the position of the valve stem
at the valve opening shifts or the closing force of the valve can
be seriously modified. Such drifts or shifts can be as large or
even much larger than the intended valve movement.
Such drift may be caused by, for example, temperature variations
that occur either from time to time or over a relatively extended
interval of time. Drift may also be caused by metal creep, or may
be due to any of a variety of other physical phenomena.
At the present time, the foregoing and other problems, when not
dealt with, result in loss of control and accuracy of such valve
systems. When dealt with, such problems require frequent mechanical
and biasing adjustments of the valve system, at a great cost in
time as well as in money.
SUMMARY OF THE INVENTION
The present invention is directed to a new actuator system and
especially to the use of such an actuator systems in a valve system
for fluid handling. It also relates to methods and systems for
using such an actuator system and to such valve systems using such
an actuator system. It also relates to techniques for operating
valve systems having close mechanical tolerances and/or small
dimensions and/or small amounts of movement.
In the practice of the present invention, using the actuator
systems of the present invention, devices, such as small valves and
the like, may be fabricated utilizing conventional tolerances,
which devices will perform in a controlled manner and with accuracy
over extended intervals of time and under varying environmental
conditions, essentially without the requirement for frequent
mechanical and biasing adjustments of the type now required.
In preferred embodiments, the actuator system of the present
invention will be used in valve systems which control the passage
of fluids through a passageway. In such valve systems a support
structure or frame will be provided for the valve system and
actuator so that the actuator follower or stem will be
operationally located with its nondriven end adjacent to or in
contact with the valve seat opening, for example to a passageway.
In such preferred embodiments the passageway opening-closing end
portion of the valve stem will be substantially aligned with the
valve seat, and movable with respect to the valve seat between at
least a first position closing the valve seat and a second position
away from the valve seat passageway. In preferred embodiments the
follower or valve stem will be movable in response to the force
transfer surface of the actuating device of the present invention,
to a continuously variable number of positions. In some preferred
valve system embodiments an additional and separate biasing
mechanism is provided which biases the opening-closing end portion
of the stem towards a selected normally open or normally closed
position with respect to the valve seat passageway.
More specifically, the present invention relates to an improved
actuating system in which a follower is adjacent to but separated
from the actuating device by viscous material. The actuating system
includes an actuating device having a force transfer surface
portion, which force transfer surface portion has a normal rest
position, but which can be driven and caused to move. The follower
portion of the actuating system, which may be a valve stem or a
portion of a valve stem, will be adjacent to, but separated from
the force transfer surface portion of the actuating device, with
viscous material coupling material intermediate and in contact with
both the force transfer and follower. The viscous material will
allow almost immediate and complete transfer of rapid movement and
force from the force transfer surface of the actuating device to
the follower, but as long as they are not rapid will absorb
relatively large drifts and shifts in the actuating device and
support structure without causing any substantial shifts in the
follower or stem.
The coupling composition will be a viscous material. In some
embodiments having the viscous coupling material can have a
viscosity in the range of about 10.sup.-2, for example a gas, to
about 10.sup.12 centipoise, for example, characteristic of flowable
pitch. In most embodiments the viscous coupling material will have
a range of about 1 to about 10.sup.10 centipoise, with the
preferred range being about 10.sup.3 to 10.sup.7 centipoise which
is characteristic of many stable siloxane fluids. One specifically
preferred viscous material is polydimethyl siloxane having a
viscosity of about 10.sup.6 centipoise. However, in general, any
viscous material, mixture of viscous materials, or viscous material
including non-viscous filler, which material provides the required
properties, may be used in the practice of the present
invention.
Where the actuating device includes piezoelectric ceramic material,
the movable force transfer surface of the actuating device will be
driven by electromotive means operatively associated with the
actuating device to drive the movable force transfer surface to at
least one position, but more typically to a continuous variety of
positions, which will be different from its rest position. Such a
piezoelectric system may be a single piezoelectric element, a stack
of piezoelectric elements, a bender bimorph, or any other form of
piezoelectric ceramic actuator. The actuating device may also be
any other suitable mechanism, whether electrical, mechanical or
hydraulic, which provides controllable and predictable motion of a
force transfer surface away from a rest position. In preferred
embodiments the actuating device will be capable of controlled,
rapid bidirectional movement.
In preferred valve system embodiments of the present invention the
follower will be a substantially linear valve stem, having a first
and a second end. The first end of the valve stem will be located
adjacent the movable force transfer surface of the actuating
device, while the second end of the valve stem will define or be
linked to an opening-closing surface portion, as detailed below.
The viscous coupling material will be positioned intermediate the
movable force transfer surface of the actuating device and the
adjacent first end portion of the valve stem. The viscous coupling
material will be in intimate and substantially continuous coupling
contact with both surfaces. Any movement of the force transfer
surface which is fast, relative to the deformation time of the
viscous coupling material, will cause the viscous material to
transmit substantially all controlled dynamic movement and force
from the movable force transfer surface of the actuating device to
the first adjacent surface of the valve stem, and thus move the
entire valve stem. However, the same viscous material will transmit
substantially no force or movement between the movable surface of
the actuating device and the first adjacent end of the valve stem
when the movement of the movable force transfer surface is slow
relative to the deformation time of the viscous material. Thus,
slower variations in the actuating device, variations in any
separate actuating device, and variations in any other valve system
component, due, for example: to stress, aging drift, and
temperature variations will not be transferred from the force
transfer surface through the viscous coupling material to the
follower or stem. As a result, devices of the present invention
will be expected to perform over extended intervals and under
varying environmental conditions, without the requirement for
mechanical and biasing adjustments of the type now required.
The present invention will also provide a combined valve system and
passageway, wherein the valve system will control the flow of fluid
between an inlet and an outlet of such a passageway, and in which a
valve stem seat is present at the inlet of the passageway. In such
a structure the valve system will have a valve stem having a
closure surface, which closure surface will be substantially
aligned with the valve seating opening, and which stem closure
surface is movable with respect to the valve seating opening from a
first position abutting and closing the valve seating opening to
one or more positions spaced from the valve seat opening. As
described above, an actuating device coupled to the valve stem and
having a movable force transfer surface for transferring movement
of the stem to move its closure surface towards at least one second
(opened) position will be provided. The combined valve system and
valve seating structure will include a viscous force transfer
material in intimate contact with both the movable surface of the
actuating component and the stem. The valve system will be actuable
from its normally closed rest state to an open actuated state in
which the movable surface of the actuating device will cause
movement of the stem by transmitting dynamic force through the
intermediate viscous coupling material.
In the practice of the present invention utilizing the disclosed
actuating system, once the actuating device is activated in a
manner to move the force transfer surface away from the follower,
the follower will tend to move in the same direction as the force
transfer surface due to the connection provided between them by the
viscous coupling material. However, since all or a substantial
amount of the transmitted force and movement of the follower is due
to the viscosity of the viscous force transfer material, and since
this viscous force is maintained only by the deformation rate of
the viscous material, once the movement of the force transfer
surface has stopped, the follower, if normally so biased, will
slowly move away from the stationary force transfer surface. For
example, if the follower is a valve stem, the valve will resume its
normally closed or normally open position. Therefore, for the
actuator to be useful in the sense of being more than a "one shot"
operation, the actuator must, from time to time, be deactivated so
that the force transfer surface and the follower are repositioned
in close relationship and the viscous force transfer material can
relax and return to an unactivated rest position. After this
relaxation period, during which any drifts in the dimensions or
locations of the various components of the actuation system can be
accommodated, the actuator system can be actuated again. Thus, over
an indefinite time period, the viscous-material-filled gap between
the force transfer surface of the follower can absorb relatively
large shifts or drifts while still accurately transmitting the
relatively small rapid movements of the actuator device.
In practice, a valve including the actuator system of the present
invention can be, for example, operated with rapidly repeating
cycles which open and then close the valve to provide a desired
fluid flow through the valve system passageway. Or, as another
example, a valve system passageway may be opened long enough to
provide some desired amount of fluid flow and then closed until
such as more flow is desired.
With suitable choice of viscous material and gap dimensions, the
actuation time of the valve before, say, ninety percent (90%) of
the initial stem movement has been lost due to viscous creep can be
from much less than a millisecond to 1000 seconds or more, if
practical. Periods of actuation will be a function of the viscosity
of the material, the direction of deformation. If nearly complete
relaxation of the material is required by the particular
application, then the off time of the valve must be comparable to
these times.
In some instances it may be desirable to minimize the time required
for relaxation, for example where it is desired to maximize valve
fluid throughout for a given maximum available actuator movement.
For such an application, it may be advantageous to use a viscous
material that varies its viscosity with time or as a function of
applied energy. Using such a material, during the relaxation period
the viscosity of the material could be increased or reduced, for
example by applying an electric field, to vary the relaxation time.
However, in most instances successful actuator or valve operation
will not require complete relaxation of the viscous material during
the off period, as in some applications only a partial relaxation
may suffice.
These and other objects of the present invention will become
apparent to those skilled in the art from the following detailed
description, showing the novel construction, combination, and
arrangement of parts as herein described, and more particularly
defined by the appended claims, it being understood that such
changes in the precise embodiments of the herein disclosed
invention are meant to be included as come within the scope of the
claims except insofar as precluded by the prior art.
For a fuller understanding of the nature and objects of the
invention, reference should be had to the following detailed
description taken in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate complete preferred embodiments
of the present invention according to the best mode presently
conceived for the practical application of the principles thereof,
and in which:
FIG. 1 is a schematic cross-sectional portrayal of a valve system
structure in a mass spectrometer including the actuating system of
the present invention, with the valve in a "closed" position:
FIG. 2 is a broken-away, schematic cross-sectional portrayal of the
valve closure portion and valve seat of FIG. 1 in an "open"
position;
FIG. 3 is a schematic cross-sectional portrayal of a modified valve
system structure according to the present invention; and
FIGS. 4 and 5 are schematic portrayals of modified actuating
systems in use with a workpiece other than a valve, according to
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a simplified schematic cross-sectional
representation of a controlled fluid passageway in a mass
spectrometer is set forth, including a typical actuating system in
conjunction with a valve system which may be produced in accordance
with the instant invention. The system of interest 10 will include
upper support structure 12 and lower support structure 14. Lower
support structure 14 defines fluid duct area 16 within itself.
Upper support structure 12 defines actuator receiving chamber 18
within itself. Chamber 18 will be remotely positioned from duct 16.
Secured between upper support 12 and lower support 14 will be
flexible ring diaphragm 19, including a central opening which will
support cylindrical open bushing 20.
Support structure 14 will support and define cylindrical passageway
22 which will provide an opening therethrough to provide a path for
fluids to pass to or from duct 16, as detailed below. The top
portion of passageway 22 which will be in contact with duct area 16
will provide an opening or "valve seat" 28 for control by the valve
system of the present invention, as hereinafter explained.
Valve seat 28 will be selectively closed and opened by closure
component 30. In the illustrated embodiment of FIG. 1, closure
component 30 is present as a ball or sphere which will in turn be
secured within socket 32 coupled to hollow enclosing biasing
structure 34. In the embodiment shown in FIG. 1, biasing structure
34 will be a closed, continuous, substantially cylindrical spring,
having the form of a bellows. Upper cylindrical portion 36 of
biasing structure 34 will be positioned and fixed, for example by
adhesive 46 within a corresponding cylindrical opening 39 formed
through support structure 14 and extending between duct 16 and
actuator chamber 18. Biasing structure 34 and connected spherical
member 30 will both be co-axially aligned with the central axis of
passageway 22, and biasing structure 34 will serve to assert a
continuous downward spring bias which will assure the seating of
sphere 30 against valve seat 28 of passageway 22 to provide a
normally closed passageway configuration, as shown in FIG. 1.
Bellows structure 34 will also surround valve stem component 40.
The lower end of stem 40 will be continuously coupled to socket 32,
while bellows structure 34 is sealed against the upper surface
portion of socket 32. Stem 40 will extend upwardly through upper
cylindrical portion 36 of biasing member 34 into actuator chamber
18. In the preferred embodiment, the upper portion of stem 40
within chamber 18 will be configured to provide an enlarged upper
force transfer surface portion 42 having a force receiving surface
43.
Also located within chamber 18 will be an actuating device 44. As
represented in FIG. 1 actuator device 44 is a stack of piezoceramic
crystal elements. Such a piezoelectric stack will be formed
generally as a lamination of a plurality of thin piezoelectric disk
elements, mounted to the roof of chamber 18, for example using an
adhesive 46. Electrical leads 48 and 50 are shown coupled to the
piezoelectric stack or actuator device 44 and, upon the application
of an appropriate electrical signal, stack 44 will be actuated to
move or be driven either upwardly, in the embodiment shown in FIG.
1, or with appropriate adjustments, downwardly. Additionally, the
amplitude of flexure of stack 44 will be accurately controlled by
the strength of the applied electrical signal (voltage), while the
rate of the movement will be controlled by the rate of change of
the electrical signal. In preferred embodiments such control will
be provided by a servo feedback system of the type disclosed and
detailed in U.S. Pat. Nos. 3,895,231; 3,926,209 and 4,018,241; all
of which are incorporated herein by reference, as though set forth
in their entirety.
Attached to the lowermost surface of stack 44 will be stiffener 52,
which will provide a planar force transfer surface 54 which will be
positioned closely adjacent to, but spaced from upper force
transfer surface 43 of head component 42 of stem 40. Thus, a gap 56
will be defined between force transfer surface 54 of stiffener
element 52 and upper force receiving surface 43 of stem 40. Within
gap 56 there will be located a
viscous-coupling-force-transfer-material 58.
Viscous-coupling-material 58 will not transmit slow movement
between elements 42 and 52. However, when piezoceramic stack 44
will be electrically actuated so as to cause rapid, dynamically
activated movement of element 52, then the forces of movement of
surface 54 of element 52 will be instantaneously, and substantially
completely transmitted through viscous coupling material 58 to
force receiving surface 43 of force transfer element 42 to stem 40,
It will thus be noted that while forces due to controlled rapid
excitation and consequent movement of force transfer element 52 of
actuator device element 44 impart motive force to stem component 40
through viscous coupling material 54, viscous material 58 will
accommodate slow variations in the width of gap 56 without
transmitting any substantial force or movement to force transfer
surface 43 of stem 40. Thus, shifts or drifts in the actuator
system due to processes which cause slow movement, such as aging or
temperature will be absorbed by viscous material 58 and will not
cause movement of stem 40 or opening of valve seat 28.
In the normal embodiment shown by FIG. 1, sphere 30 is resident and
biased by bellows 34 within valve seat 28 to provide a normally
closed situation between passageway 22 and duct 16. When actuated,
piezoelectric stack 44 will move rapidly upward, moving stiffener
52 with it so as to apply movement to viscous force transfer
material 58, which will in turn cause stem 40, socket 32 and sphere
30 to move upward to disengage sphere 30 from valve seat 28, as
shown in FIG. 2. This will allow fluids to travel between duct 16
and passageway 22. The designation of outlet and inlet ducts
respectively at 16 and 22 may be considered somewhat arbitrary, as
their functions can be easily reversed.
Referring now to FIG. 3, a simplified schematic cross-sectional
representation of a controlled fluid passageway 122, is set forth,
including a modified valve system which may be produced in
accordance with the instant invention. The entire system 110 will
include a valve and actuator support structure 112 and passageway
structure 114, defining duct area 116 between them. Additionally,
support structure 112 defines actuator chamber 118. Support
structure 114 will support and define cylindrical passageway 122
which will provide an opening therethrough to provide a path for
fluids to pass to or from duct 116. The top portion of passageway
122 which will be in contact with duct area 116 will provide an
opening or "valve seat" 128 for control by the valve system of this
embodiment.
Valve seat 128 will be selectively closed and opened by the
operation of stem component 140. In the illustrated embodiment of
FIG. 3, closure component 140 will terminate in a needle tip 130
which will, in turn, be secured within cylindrical socket 152.
Closure component 140 will be coaxially aligned with the central
axis of passageway 122, to provide a normally open, but closable,
passageway configuration.
In the embodiment of FIG. 3, an additional stem portion 160 will be
connected to socket 152 and extend within chamber 118. The inner
surface of socket 152 will define a force transfer surface portion
154.
Also located within chamber 118 will be an actuating device 144. As
represented in FIG. 3, actuator device 144 may be any controllable
electrical, mechanical or hydraulic actuating device. The amplitude
of flexure of actuating device 144 will be accurately controlled by
the system. Attached to the lowermost surface of element 144 will
be stem portion 160, to which, in turn, will be connected socket
152 having force transfer surface 154. Force transfer surface 154
will be positioned around and closely adjacent to but spaced from
force transfer surfaces 142 of cylindrical stem component 140.
Thus, a cylindrical gap will be defined between force transfer
surface 154 of socket 152 and surface 142 of stem 140. Within that
cylindrical gap there will be located a viscous coupling material
158. Viscous coupling material 158 will be selected so that it does
not transmit forces or movement between elements 140 and 152 when
element 152 coupled to actuating device 144 is normally at rest,
that is when element 144 is not being rapidly actuated. However,
when actuating device 144 will be actuated so as to cause rapid,
dynamically activated movement of element 152, then the forces of
movement of surface 154 of element 152 will be instantaneously and
substantially completely transmitted through viscous coupling
material 154 to force transfer element 142 of stem 140. It will
thus be noted that while forces due to controlled excitation and
consequent movement of elements 145 of actuator element 144 impart
motive force to stem component 140 through viscous coupling
material 154, that during rest intervals, material 154 accommodates
variations in the width of gap 158 without transmitting any
substantial force or movement to force transfer surface 142 of stem
140. Thus, movement in the system due to aging, temperature, shift
or drift will not cause movement of stem 140 or opening of valve
seat 128.
Now, referring to FIGS. 4 and 5, modified actuator systems in
accordance with the present invention are shown schematically for
use with workpieces and other than valve stems and valve systems.
In FIG. 4 the system, generally 210, includes an actuator device or
drive 244, which may be a piezoelectric device, an electronic,
mechanical or hydraulic system capable of providing rapid,
controlled movement to a force transfer element 252 having force
transfer surface 254. Prezoelectric devices of choice include
prezoelectric stacks, bender bimorphs, single component cylinders,
and single component disks. In this embodiment, force transfer
surface 254 is irregular, being a series of teeth or cones on its
surface. Opposed to, but spaced from force transfer element 252 is
force receiving follower 242 having a force receiving surface 243.
Force receiving surface 243 is also irregular, being designed to be
substantially complementary to force transfer surface 254. The gap
formed between force transfer surface 254 and force receiving
surface is preferably about five mils or less and substantially
filled with viscous force transfer material 258. Associated with
follower 242 is workpiece 240 which may be a valve stem, an optical
element such as a mirror, a hammer, for example, a printer wire, a
stylus or any other workpiece element which requires controlled and
accurate actuation
In operation, actuation of driver 244 towards or away from follower
242 will result in substantially simultaneous and similar movement
of follower 242 and associate workpiece 240 due to the transfer of
force through viscous material 258. The configuration of the force
transfer and receiving surfaces 254 and 243 of the system of FIG. 4
assures similar lateral as well as longitudinal movement. However,
even in the absence of irregular surfaces, the shear
characteristics of viscous material 258 will provide similar
lateral movement between force transfer and receiving elements.
In a similar manner, FIG. 5 discloses a system in accordance with
the present invention in which the viscous material can be modified
electrically. In the system driver 344 and associated force
transfer element 352 terminate in force transfer surface 354.
Spaced therefrom is force receiving element 342 having force
receiving surface 343 and associated with workpiece 340. Force
receiving and transfer surfaces 343 and 354 are spaced from one
another to define a gap which is substantially filled, or
overfilled, with electroviscous material 358. Viscous material will
remain in the gap due to surface tension. Surface 343 is conductive
and has electric lead 372 associated with it while surface 354 is
also conductive and has electric lead 374 associated therewith.
This system operates in much the same manner as the above described
systems, with the exception that by electrification of surfaces 343
and 354, an electric field gradient will be provided in the gap.
Such an electric field can alter the viscosity of electroviscous
material 358. Increasing or decreasing of viscosity can affect
either the efficiency or relaxation characteristics of the
system.
It is, therefore, seen that the present invention provides systems
in which viscous material is used to couple an actuating device and
a follower system. This provides a simple, effective and
inexpensive system for providing accurate and controlled
positioning of movable elements. The provision of a gap or space
between such elements and the use of viscous material in the gap or
space can accommodate deviations which could otherwise be critical
in the positioning of the driver. In the practice of the present
invention, such deviations will not seriously affect the follower
as the viscous gap is capable of closing or expanding as required
to accommodate variations in the system due to temperature changes,
shift or drift.
Since certain changes may be made in the above-described apparatus
and method without departing from the scope of the invention herein
involved, it is intended that all matter contained in the
description thereof or shown in the accompanying drawings shall be
interpreted as illustrative and not in a limiting sense.
While the invention has been particularly shown and described with
reference to preferred embodiments thereof, it will be understood
that those skilled in the art that the foregoing and other
modifications or changes in form and details may be made therein
without departing from the spirit and scope of the invention as
claimed, except as precluded by the prior art.
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