U.S. patent application number 10/485908 was filed with the patent office on 2004-11-25 for dosing pump.
Invention is credited to Bolt, Erwin.
Application Number | 20040234377 10/485908 |
Document ID | / |
Family ID | 7710050 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040234377 |
Kind Code |
A1 |
Bolt, Erwin |
November 25, 2004 |
Dosing pump
Abstract
A dosing pump is provided comprising a working membrane defining
a working area, and a pump drive for creating an oscillating
movement of the working membrane. The direction of the pump drive
can be inverted and the displacement element can be moved back and
forth. The inventive dosing pump also comprises a position sensor
for detecting the position of the pump drive, an electronic control
system for the same, and a pump head in which an inlet valve and an
outlet valve are arranged. The pump drive comprises a positioning
motor and can be displaced back and forth in an oscillating manner,
with the part thereof connected to the displacement element, in any
range of its entire working displacement, according to a
pre-determinable course, for a reduced pump capacity in relation to
the maximum pump capacity. At least the inlet valve is externally
controlled and comprises a motor-driven valve drive. The electronic
control system is connected to at least the motor-driven valve
drive(s) of the inlet and/or outlet valves, to the positioning
motor of the pump drive, and to the position sensor for detecting
the position of the displacement element and/or the pump drive. The
combination of the electronically controllable positioning motor,
the oscillating movement of the pump drive within any range of its
entire working range, and the use of an externally controlled inlet
and/or outlet valve significantly enlarges the operative range of
the inventive dosing pump.
Inventors: |
Bolt, Erwin; (Brugg,
CH) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
UNITED PLAZA, SUITE 1600
30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103
US
|
Family ID: |
7710050 |
Appl. No.: |
10/485908 |
Filed: |
February 4, 2004 |
PCT Filed: |
October 4, 2002 |
PCT NO: |
PCT/EP02/11151 |
Current U.S.
Class: |
417/44.1 ;
417/413.1; 417/415 |
Current CPC
Class: |
F04B 7/0076 20130101;
F04B 13/00 20130101; F04B 2201/0201 20130101; F04B 49/065 20130101;
F04B 2201/1208 20130101 |
Class at
Publication: |
417/044.1 ;
417/413.1; 417/415 |
International
Class: |
F04B 049/06; F04B
017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2001 |
DE |
101 62 773.4 |
Claims
1. A diaphragm dosing pump comprising a working membrane or a
similar displacement element defining a working area and a pump
drive (2) for creating an oscillating movement of the displacement
element, whereby the pump drive (2) can be reversed in direction
and the displacement element can be moved back and forth, whereby a
position sensor for detecting a position of the pump drive (2) and
an electronic control system (7) for the pump drive are also
provided, as well as a pump head, in which an inlet valve and an
outlet valve (14) are arranged, the pump drive (2) has a
positioning motor and can move back and forth in an oscillating
movement, by a part connected to the displacement element, in any
range of a total working movement by a stroke that can be preset
for a feeding amount that is reduced relative to a maximum feeding
amount, at least one of the valves (13) is remote controlled and
has a motor-driven valve drive, and the electronic control system
(7) is connected to the motor-driven valve drive of the inlet
and/or outlet drive (14), to the positioning motor of the pump
drive (2), and also to a position sensor for detecting a position
of the displacement element and/or the pump drive (2).
2. A dosing pump (1) according to claim 1, wherein the pump drive
(2) is configured and controlled by a part connected to the
displacement element for a feeding amount per working stroke that
is increased or at a maximum relative to a reduced feeding amount
by a working stroke that can be moved back and forth in an
oscillating movement.
3. A dosing pump (1) according to claim 1, wherein the electronic
control system (7) is configured for variable control of the
motor-driven valve drive of the inlet (13) and/or outlet valve (14)
as a function of the position of the displacement element.
4. A dosing pump (1) according to claim 1, wherein the electronic
control system (7) is configured for controlling the motor-driven
valve drive(s) of the inlet (13) and/or outlet valve (14) as a
function of different operating parameters, comprising at least one
of a function of operating pressure, rpm, and consistency of the
pumping medium.
5. A dosing pump (1) according to claim 1, wherein the electronic
control system (7) has a memory device for storing different
operating parameters and for assigning these operating parameters
to different control times of the valves.
6. A dosing pump (1) according to claim 1, wherein one or more
measurement devices for measuring operating parameters, comprising
at least one of operating pressure, counter pressure, rpm, and pump
capacity are provided.
7. A dosing pump (1) according to claim 1, wherein the pump drive
(2) has a cam or crank drive (9) with a rotating crank element (10)
and a connecting rod (11) connected to the working membrane or a
similar displacement element and the crank element (10) for small
deflections of the working membrane relative to the maximum
possible deflections for one rotation movement can move back and
forth in an oscillating movement in any range within a total
rotational movement.
8. A dosing pump (1) according to claim 1, wherein the electrically
remote-controlled valve (15) is closed in an inactive state.
9. A dosing pump (1) according to claim 1, wherein the inlet and/or
outlet valve (13, 14) has as a motor-driven valve drive an
electromagnet stroke magnet (5, 6), which has a stroke armature
(25) guided by leaf springs (23, 24) spaced apart from each other,
which is in drive connection to a valve closing body (26).
10. A dosing pump (1) according to claim 9, wherein at least one of
the leaf springs (23, 24) of the stroke armature guide is
pre-tensioned in the closing direction of the remote-controlled
valve (15).
11. A dosing pump (1) according to claim 1, wherein in addition to
a remote controlled valve, there is at least one valve (15) that
can be activated by the pumping medium, especially formed with an
elastic valve disk (17), which in the closed position contacts with
a flat side onto the opening edge (20) of a supply channel (21)
forming a valve seat, and on the side of the valve disk facing away
from the supply channel (21), a bridge-like support (22) supports
the valve disk (17) at least in an the opened position within the
extended projection of the supply channel (21).
12. A dosing pump (1) according to claim 11, wherein the valve (15)
that can be activated by the pumping medium forms a complete,
exchangeable unit and is configured as a valve insert (21) with a
support plate (16) having support (28) and a discharge channel
(31), a valve holding plate (18), the valve disk (17), support
plate (16) and the valve holding plate (18) preferably have edge
formations that engage with each other and are welded, adhered, or
connected to each other in the assembled position.
13. A dosing pump (1) according to claim 1, wherein the output
position of the working membrane (6) is the same at the beginning
and end of a dosing.
14. A dosing pump (1) according to claim 1, wherein a number of
working strokes of the working membrane (6) per unit of time and/or
the working rate can be adjusted.
15. A dosing pump (1) according to claim 1, wherein the pump drive
(2) has as a drive and positioning motor (12) a controlled or
regulated motor, particularly a stepper motor or a motor working in
a control loop.
16. A dosing pump (1) according to claim 1, wherein a non-contact
optoelectronic or magnetic position sensor (32) is provided as the
position sensor (32), which interacts with the positioning motor
(12) or a part driven by this motor and is connected to the control
electronics (7).
17. A dosing pump (1) according to claim 1, wherein the electronic
control system (7) is configured for setting a non-uniform drive
rate of the drive.
18. A dosing pump according to claim 1, wherein the two valves are
remote-controlled and can be controlled selectively as an inlet
valve or outlet valve for reversing a feeding direction.
Description
BACKGROUND
[0001] The invention relates to a dosing pump, particularly a
diaphragm dosing pump comprising a working membrane or a similar
displacement element defining a working area and a pump drive for
creating an oscillating movement of the displacement element. The
direction of the pump drive can be reversed and the displacement
element can be moved back and forth. The invention also comprises a
position sensor for detecting the position of the pump drive and an
electronic control system for the drive, as well as a pump head, in
which an inlet valve and an outlet valve are arranged.
[0002] Dosing pumps of this type are known in various
configurations. There are known dosing pumps, which operate by a
magnetic drive and execute fast working strokes. This pulse-like
feeding produces sufficient pressure differences for the control of
the valves.
[0003] For dosing pumps, in which a small feeding rate and small
doses are desired, motor-driven rotary drives which run very
slowly, at least in the dosing stroke, are used. Corresponding by,
small pressure differences appear, so that sealing problems can
occur for the valves.
[0004] From EP 0 321 339, a device for regulating the pump capacity
of a dosing pump is known, with which the feeding stroke or the
number of feeding strokes per unit of time can be changed.
[0005] The feeding stroke is changed by moving the pump drive
forwards and backwards for different rotational segments with
corresponding different strokes, starting from a defined home
position.
[0006] In such dosing pump, sealing problems also occur at the
valves for adjustable, small doses, thereby considerably reducing
the desired dosing accuracy of the pump.
[0007] From DE 195 25 557.7, a diaphragm dosing pump is known,
whereby special valves are used in order to avoid, at least for the
most part, the previously mentioned disadvantages for a low working
rate and small pressure differences, as well as small dosing
amounts. However, here a minimal pressure difference is necessary
for opening and closing the valves.
[0008] However, for dosings where the working stroke is drawn over
a long period of time, e.g., a few minutes, a reliable seal can
also not be achieved with these fine acting valves.
[0009] Furthermore, dosing pumps are known, wherein a mechanical
change of the stroke length is performed to adjust the dosing
amount. Therefore, small dosing amounts having a sufficiently high
feeding rate, which produces a sufficient pressure difference and
is sufficient for the functioning of the valves, can also be
processed. However, the pumping medium is discharged at a high
speed corresponding to the working rate sufficient for the
functioning of the valves. This pulse-like feeding is undesirable
in many dosing pumps applications.
[0010] Both slow and fast-running pumps produce conflicts between
the valve functions, which have disadvantageous effects on, among
other things, the pressure and suction side pressure relationships
in the form of a reverse flow of pumping medium against the feeding
direction thus producing dosing inaccuracies.
SUMMARY
[0011] The object of the present invention is to create a dosing
pump, which can cover a broad operating range with very small
dosing amounts and high repeatability, and which can provide exact
adjustability of the pump over a wide range of operating
conditions, wherein the pump shall exhibit high dosing accuracy
both for large and also for very small feeding amounts and wherein
the feeding rate can also be set to an extremely low value while
maintaining high dosing accuracy.
[0012] To achieve this object, it is proposed that the pump drive
has a reciprocating positioning motor with a part connected to a
displacement element that can move back and forth in any range of
its total working movement with a predetermined stroke for a
feeding amount that is reduced relative to the maximum feeding
amount. The pump further comprising two or more valves whereby at
least one is remote controlled and has a motor-driven valve drive.
An electronic control system is connected at least to the
motor-driven valve drive or drives of an inlet and/or outlet valve,
to a pump drive, and also to a position sensor for detecting the
position of the displacement element and/or the pump drive.
[0013] The combination of an electronically controllable
positioning motor, a reciprocating movement of the pump drive
within any range of its total working area, and also the use of a
remote-controlled inlet and/or outlet valve enables a considerably
expanded usable range of a dosing pump equipped with these
devices.
[0014] Thus, there is the possibility of allowing the dosing pump
to operate for very small dosing amounts at an extremely low
feeding rate and to achieve an exact dosing through the valve or
valves, which can be precisely controlled by the electronic control
system and thus opened or closed at predetermined times independent
of feeding pressure differences.
[0015] Alternatively, in a higher pump capacity and fast-running
pump drive, a reverse flow can be prevented due to counter pressure
of the pumping medium by means of matching closing and opening
times by the remote-controlled valve. This also contributes to an
improvement in the dosing accuracy and universal application of the
dosing pump.
[0016] Finally, in addition to an adapted control of the
positioning motor by the electronic control system, through the
reciprocating stroke movement in any range of the total working
movement for a rotary pump drive, the reciprocating stroke can be
influenced as a function of the position within the total working
area.
[0017] Thus, by selecting the position of the oscillating stroke
movement according to the task, within a 360.degree. total working
area, the effective stroke of the displacement element can be
influenced. For an oscillating stroke movement in the area of a
dead center position of a pump drive with a crank mechanism, for a
given rotational movement, a smaller effective stroke is produced
than in an area between these two dead center positions.
[0018] The dosing pump according to the invention can be operated
both in any range of the total working movement of its pump drive
with an oscillating working stroke moving back and forth and also
rotating with maximum working stroke and corresponding maximum
feeding amount per working stroke. This produces a wide range of
uses for the dosing pump.
[0019] The electronic control system can be configured for variable
control of the motor-driven valve drive or drives of the inlet
and/or outlet valve as a function of the position of the
displacement element. Furthermore, the electronic control system
may control the motor-driven valve drive or drives of the inlet
and/or outlet valve as a function of different operating
parameters, especially as a function of operating pressure,
revolutions per minute (rpm), consistency of the pumping medium,
and the like.
[0020] For example, the switching positions of the valve or valves
within a rotating or an oscillating stroke area are chosen as a
function of the operating pressure, such that pump capacity loss
due to counter pressure is minimized. The matching switching
positions can be determined through tests, furthermore, there is
also the possibility of performing a variable correction of the
switching positions as a function of operating pressure, if this is
changed. The corresponding default settings can be set manually or
by analog or digital means.
[0021] The electronic control system can have a memory means for
storing various operating parameters and for assigning these
operating parameters to different control times of the valve or
valves. The operating parameters stored in the memory means can be
selected either manually or selected by measuring the actual
operating parameters and assigning the stored operating
parameters.
[0022] For the latter case, corresponding measurement devices for
measuring, e.g., operating pressure, counter pressure, rpm, and the
like are provided.
[0023] In a preferred embodiment that has been reduced to practice,
the pump drive can have a cam or crank drive with a rotating crank
element and a connecting rod connected to the working membrane or a
similar displacement element, wherein the crank element can be
moved back and forth in an oscillating movement in any range within
the total rotational movement for small deflections of the working
membrane relative to the maximum possible deflections for a
rotational movement. The cam or crank drive converts a rotating
movement into a linear movement of the displacement element. This
executes back and forth movements within the extreme positions in
the upper and lower dead centers of the crank drive. In contrast,
the oscillating stroke movement provides a small working stroke and
has a significantly smaller amplitude, wherein the drive does not
rotate, but instead moves back and forth correspondingly within the
possible rotation of its rotating crank element by controlling the
driving positioning motor correspondingly.
[0024] Here, the reciprocating stroke movement with reduced
amplitude relative to the maximum amplitude, both the number of
working strokes of the working membrane, or the like, per unit of
time and/or the drive speed can be adjusted. The dosing amounts can
be influenced by both measures and also the pump characteristics,
particularly with regard to the feeding rate. Thus, for a constant
feeding amount, a smaller stroke at a higher working speed or the
inverse, a larger stroke at a lower working speed, can be set. In
the latter case, the pumping medium is fed more gently.
[0025] Furthermore, the electronic control system may be set to a
non-constant drive speed of the drive motor, particularly for a
fast suction stroke and a correspondingly slower dosing stroke.
Thus, an irregular or pulse-like discharge of the pumping medium
can be reduced. This compensation corresponds approximately to a
sinusoidal movement with the overlapping of hydraulic phenomena
unique to diaphragm pumps. The matching stroke compensation can be
preset by a speed profile per rotation or working stroke, which is
stored as parameters in the electronic control system.
[0026] According to one embodiment of the invention, the inlet
and/or outlet valve can have an electromagnetic stroke magnet as a
motor-driven valve drive. The electromagnetic stroke magnet has a
stroke armature that is guided by means of leaf springs set at a
distance from each other and that is in drive connection with a
valve closing body. The support of the armature of the stroke
magnet with the help of at least two leaf springs produces a spring
parallelogram suspension, which is practically free from wear and
tear and insensitive to contamination, because there are no parts
supported by sliding guides. Simultaneously, the armature is
precisely guided in the radial direction and play-free in the
stroke direction. The stroke drive for the inlet valve and/or for
the outlet valve has an especially long service life due to these
means.
[0027] Advantageously, at least one of the leaf springs of the
stroke armature guide is pre-tensioned in the closing direction of
the remote-controlled valve. The valve is therefore closed for an
inactive stroke and thus sealed tightly against reverse flow. In
addition, a cost-effective, simple-acting stroke electromagnet can
be used, because the leaf spring(s) can assume the closing movement
of the valve.
[0028] According to one configuration of the invention, instead of
a remote-controlled valve, at least one valve particularly with an
elastic valve disk, that can be activated by the pumping medium.
The elastic valve disk contacts, in the closing position with a
flat side on the opening edge of a supply channel forming a valve
seat. On the side of the valve disk facing away from the supply
channel there is a bridge-like support supporting the valve disk at
least in the valve opening position within the extended projection
of the supply channel.
[0029] The provided construction of the valve produces a good seal
also for only small pressure differences possibly occurring during
operation. Therefore, the pump has good vacuum properties even at
low working speeds.
[0030] It is advantageous if the previously described valve that
can be activated by the pumping medium forms a complete,
exchangeable unit and is formed as a valve insert with a support
plate having the support and a discharge channel, a valve holding
plate, and also the valve disk, and that preferably the support
plate and the valve holding plate have edge formations that engage
each other and are especially welded, adhered, or similarly
connected to each other in the assembled position.
[0031] Therefore, the parts for the complete valve inserts can be
manufactured independently of the pump head, in which the valve
insert is inserted, which has considerable advantages in terms of
accuracy for molding technology.
[0032] The high precision of valve parts leads to, among other
things, a tension-free support of the valve disk, which is a
prerequisite for acceptable operation of the valves with good
sealing even at low pressure differences and very slow movement
sequences. In addition, the valve inserts can be exchanged as a
whole very simply.
[0033] The pump drive can have, as the drive and positioning motor,
a controlled or a regulated motor particularly a stepper motor or a
motor regulated by a control loop, e.g., a servo DC motor or the
like. Thus, it is possible to travel a defined angle at a defined
speed. The rotational direction of the motor is reversible, so that
the correspondingly small-stroke reciprocating stroke movements can
be performed within the total working movement.
[0034] A preferred position sensor is a non-contact, e.g.,
optoelectronic or magnetic position sensor, which interacts with
the positioning motor or a part driven by this motor and is
connected to the control electronics. Therefore, the position of
the working membrane is known in each operating phase so that for a
corresponding drive motor working in a control loop, this motor
receives positioning feedback and on the other hand the inlet
and/or outlet valve can be exactly adapted to the position of the
working membrane. The position sensor can be configured so that it
outputs a reference signal at clearly defined positions, e.g., at
the top or bottom dead center, from which the intermediate
positions can be calculated within a rotation or a reciprocating
movement of the pump drive. However, the position sensor can also
have an encoder, through which the appropriate position of the pump
drive or the working membrane driven by this drive can be
determined directly.
[0035] Additional configurations of the invention are listed in the
other subordinate claims. The invention is described below in even
more detail with its essential features with reference to the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1: a perspective representation of a dosing pump with
control system,
[0037] FIG. 2: a sectional representation of a dosing pump with an
electromagnetically activated inlet valve,
[0038] FIG. 3: a longitudinal sectional representation, as well
as
[0039] FIG. 4: a cross-sectional representation of a dosing pump,
and
[0040] FIG. 5: a cross section of a valve insert.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] A dosing pump 1 shown in FIG. 1 having a motor-driven pump
drive 2 for a reciprocating movement of a displacement element. The
dosing pump 1 has a pump housing 3 with a pump head 4, in which at
least one inlet valve and one outlet valve are arranged. To
activate these valves, electromagnetic stroke drives 5, 6 are
provided in the embodiment according to FIG. 1.
[0042] The electromotor-driven pump drive 2, the electromagnetic
stroke drives 5, 6 for the valves, and a position sensor for
detecting the position of the pump drive are connected to an
electronic control system 7. With the help of this electronic
control system 7, the pump drive 2 formed can be variably
controlled by a positioning motor with reference to its rpm and its
rotational direction. In addition, the electronic control device 7
is formed so that the pump drive can move back and forth in an
oscillating movement with the positioning motor in any range of its
total working movement with a stroke that can be preset.
[0043] This reciprocating stroke movement can be used to define a
feeding amount that is reduced relative to the maximum feeding
amount. Thus, the pump drive can be operated with a rotational
angle and a speed that can be preset.
[0044] The valves provided in the embodiment according to FIG. 1
with electromagnetic stroke drives 5 and 6 also allow closing and
opening times that can be variably assigned to the working position
of the pump drive. Thus, a plurality of operating parameters can be
defined in order to be able to adapt the pumps to the widest range
of operating conditions.
[0045] In a sectional representation, FIG. 2 shows the inner
structure of a dosing pump according to the invention. This depicts
a diaphragm pump with a membrane 8 as the displacement element,
wherein the membrane has a crank drive 9 with a rotating crank
element 10 and a connecting rod 11 connected to the membrane 8 as
the pump drive. The crank element 10 is connected to positioning
motor 12 (refer to FIG. 3).
[0046] In the embodiment shown in FIG. 2, only the inlet valve 13
is provided with an electromagnetic stroke drive 5, while the
outlet valve is a valve that can be activated by the pumping
medium.
[0047] Here, the outlet valve 14 is formed as a valve that is
sensitive to small pressure differences. For certain dosing tasks,
which operate with a minimum feeding rate, this configuration
provides good use with different valves.
[0048] However, if the feeding rate falls below this minimum value
necessary for a valve activated by the pumping medium, or if
special dosing tasks are to be preformed, remote-controlled valves
are provided both for the inlet valve and also for the outlet
valve. Therefore, the closing and opening of the valves can be
performed independent of the pressure difference appearing in the
valve area. Thus, the valve function can also be decoupled from the
corresponding position of the pump drive.
[0049] For the use of a valve activated by the pumping medium, as
provided in the embodiment according to FIG. 2, valve 15 shown in
FIG. 5 can be provided selectively as an inlet valve or outlet
valve. This valve 15 for example, is configured so that it exhibits
a reliable sealing behavior even for low working or feeding rates
and the resulting low pressure differences between the suction side
and the pressure side.
[0050] The valve is formed as a disk valve and essentially has a
support plate 16, a valve disk 17, and also a valve holding plate
18. A complete, can-shaped unit as the valve insert is formed by
these three parts 16, 17, and 18. This valve insert can be inserted
into a corresponding holding recess of the pump head.
[0051] For a valve arranged on the suction side, in the closed
position the valve disk 17 lies with its flat side facing the
suction side 19 on the opening edge 20 of a central supply channel
21 forming a valve seat in the valve holding plate 18. The valve
disk 17 is fixed against lateral displacements by positioning tabs,
which are arranged laterally adjacent to the opening edge and
engage in open recesses in the edge of the valve disk 17. The
support plate 16 has a bridge-like support 22 within the extended
projection of the supply channel of the valve holding plate 18, by
means of which the valve disk 17 is supported in the opening
position approximately along its diameter. In the open position of
the valve, the valve disk tabs located on both sides of the center
support line are pivoted towards the support plate 16, so that the
supply channel 21 is opened. The distance of the plane running
through the support point of the support 22 from the parallel plane
formed by the opening edge 20 is dimensioned so that the valve disk
17 is held there tension-free. This is a prerequisite for the valve
disk to respond at very low pressure differences and also for a
fast closing or opening process.
[0052] For the use of the valve 15 on the pressure side, the valve
is inserted turned by 180 degrees.
[0053] As previously mentioned, remote-controlled valves are
preferably used both for the inlet valve 13 and also for the outlet
valve 14. One such valve is shown as an inlet valve in FIG. 2. The
electromagnetic stroke drive 5 has a stroke armature 25, which is
guided by means of leaf springs 23, 24 spaced apart from each other
and which is in drive connection with a valve closing body 26.
[0054] In the axial extension of the stroke armature 25, a
sleeve-like iron pole 27 is arranged at a distance to the armature.
Around this pole and the stroke armature there is located a coil
28, which, when it is excited, moves the stroke armature 25 in the
direction of the arrow Pf 1 and thus brings the valve closing body
26 into the open position.
[0055] A parallelogram suspension for the stroke armature 25 is
formed by the two leaf springs 23, 24, so that no parts supported
by sliding guides are necessary. Thus, the stroke armature 25 is
guided in the radial direction precisely and play-free in the
stroke direction. Preferably, at least one of the two leaf springs
of the stroke armature guide is pretensioned in the closing
direction. Therefore, in the no-current state the valve goes into
the closed position, which is shown in FIG. 2.
[0056] To transfer the stroke movement of the stroke armature 25 to
the valve closing body 26, there is a rocker lever 29, which is
coupled with its drive end to a shaft 30 connected to the stroke
armature and with its other end is connected to the valve closing
body 26. In the course of the longitudinal extension of the rocker
lever 29, there is a rocker support 31, which encloses the rocker
lever 29 in a sealing manner and which also seals a valve space
from the outside.
[0057] The rocker support is preferably formed as an elastomer
bushing, so that an absolute seal is provided.
[0058] The dosing pump 1 is equipped with a position sensor 32 for
detecting the position of the pump drive or the membrane 8 forming
the displacement element, as can be easily seen in FIGS. 3 and 4.
In this embodiment, the position sensor has a magnet 33 rotating
with the crank element 10, as well as a magnetic sensor preferably
formed as a Hall sensor and arranged stationary adjacent to the
rotational track of the magnet 33. Thus, for each rotation of the
pump drive, a reference signal is generated. The other positioning
device is oriented accordingly to this reference signal.
Particularly for the use of a stepper motor, for which the
corresponding positioning can be set by a certain number of steps,
the reference signal is used for resetting or for generating a
certain correction value. With the use of a stepper motor, very
small step angles are possible, so that the membrane 8 can be
brought into any arbitrary position within its total working area.
Thus, the setting can proceed extremely slowly, wherein working
strokes extending over several minutes are possible. However, on
the other hand, higher RPMs can also be processed in order to
achieve a high pump capacity.
[0059] In addition to the non-contact position sensor shown in the
embodiment, other sensors e.g., optoelectronic, position, can also
be used, which output a plurality of position data, if necessary,
over the course of one rotation. Here, it should be mentioned that
instead of a stepper motor, a motor working in a control loop,
e.g., a servo DC motor, can also be used.
[0060] As can be seen in FIG. 1, the positioning motor 2, the
electromagnetic stroke drives 5 and 6 for the inlet valve 13 and
the outlet valve 14, and also the position sensor 32 are connected
to the electronic control system 7. Therefore, the function of the
pump can be varied within wide limits. For example, the
electro-magnetic stroke drives 5, 6 of the valves can be controlled
as a function of the position of the membrane 8.
[0061] However, on the other hand there is also the possibility to
open or close the valves independent of the position of the pump
drive or the membrane. For example, this can occur as a function of
different operating parameters, especially as a function of
operating pressure, rpm, consistency of the pumping medium, and the
like. By the use of a memory device, there it is possible to store
different operating parameters which can then be assigned to
different control times of the valves.
[0062] For measuring operating parameters, such as, e.g., operating
pressure, counter pressure, rpm, corresponding measurement devices
are provided.
[0063] In addition to the function of the pump, mentioned above,
with a membrane that can move back and forth in an oscillating
movement within the total working movement for a reduced feeding
amount, a non-uniform working rate of the drive motor can also be
set with the help of the electronic control system 7 for a fast
suction stroke and a correspondingly slower dosing stroke.
Therefore, instead of an otherwise approximately sinusoidal fluid
feeding, the flow can be made more uniform.
[0064] If both valves are remote-controlled, then there is also the
possibility of controlling the feeding device. Even for a dosing
pump, this possibility is an advantage, because after a dosing
process with discharge of the pumping medium from the pressure
channel, undesired reverse flow or return drops of the pumping
medium can be prevented by switching the feeding direction through
the control of both valves. To prevent the previously mentioned
reverse flow or return droplets of pumping medium, a partial stroke
of the working membrane with a controlled valve closing is usually
sufficient.
[0065] This means that for the suction stroke of the membrane with
enlargement of the working space, the outlet valve is opened while
the inlet valve is closed.
[0066] The dosing accuracy of the dosing pump 1 can be
significantly improved by these measures and simpler handling is
also possible when setting the dosing amount.
[0067] The dosing pump 1 with remote-controlled inlet and outlet
valve 13, 14 can be used not only for reverse feeding for
preventing reverse flow, but also selectively for continuous
feeding in both feeding directions.
* * * * *