U.S. patent application number 09/963558 was filed with the patent office on 2002-01-24 for gear pump having a multishaft drive and method of operating same.
This patent application is currently assigned to MAAG PUMP SYSTEMS TEXTRON AG.. Invention is credited to Bussard, Maurice.
Application Number | 20020009368 09/963558 |
Document ID | / |
Family ID | 8232504 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020009368 |
Kind Code |
A1 |
Bussard, Maurice |
January 24, 2002 |
Gear pump having a multishaft drive and method of operating
same
Abstract
The invention relates to a gear pump consisting of two meshing
gears which are each assigned to a shaft and which are each driven
by means of a driving unit. The driving units are controllable by a
control unit such that the shafts rotate at a definable angular
velocity. According to the invention, the control units have a
symmetrical construction, a control device being provided in each
control unit, which control device is operably connected with the
other by way of a data line.
Inventors: |
Bussard, Maurice; (Neuenhof,
SZ) |
Correspondence
Address: |
CROWELL & MORING, L.L.P.
P.O. Box 14300
Washington
DC
20044-4300
US
|
Assignee: |
MAAG PUMP SYSTEMS TEXTRON
AG.
|
Family ID: |
8232504 |
Appl. No.: |
09/963558 |
Filed: |
September 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09963558 |
Sep 27, 2001 |
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09382830 |
Aug 25, 1999 |
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6312225 |
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Current U.S.
Class: |
417/16 |
Current CPC
Class: |
F04C 15/008 20130101;
F04C 2240/402 20130101 |
Class at
Publication: |
417/16 |
International
Class: |
F04B 049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 1998 |
EP |
98 115 962.7 |
Claims
What is claimed is:
1. Gear pump having two mutually meshing gears which are each
assigned to a shaft and which are each driven by means of a driving
unit, the driving units each being drivable by a control unit such
that the shafts rotate at a definable rotational velocity, wherein
the control units are operably connected by way of a data line.
2. Gear pump according to claim 1, wherein the control units are
constructed symmetrically with respect to one another.
3. Gear pump according to claim 1, wherein a power converter is
provided for each driving unit, each power converter being
operatively connected with a respective driving unit, and wherein a
control device is provided in each control unit for generating
control signals which act upon the corresponding power converters,
the data line existing between the two control units being guided
to the respective control devices.
4. Gear pump according to claim 2, wherein a power converter is
provided for each driving unit, each power converter being
operatively connected with a respective driving unit, and wherein a
control device is provided in each control unit for generating
control signals which act upon the corresponding power converters,
the data line existing between the two control units being guided
to the respective control devices.
5. Gear pump according claim 3, wherein the power converter output
signals, or signals proportional thereto, are returned into the
corresponding control device.
6. Gear pump according to claim 4, wherein the power converter
output signals, or signals proportional thereto, are returned into
the corresponding control device.
7. Gear pump according to claim 1, wherein the driving units are of
the asynchronous machine type.
8. Gear pump according to claim 2, wherein the driving units are of
the asynchronous machine type.
9. Gear pump according to claim 3, wherein the driving units are of
the asynchronous machine type.
10. Gear pump according to claim 5, wherein the driving units are
of the asynchronous machine type.
11. Gear pump according to claim 7, wherein the power converters
are of the inverse rectifier type for generating current voltage
and frequency.
12. Gear pump according to claim 1, wherein a rotational velocity
measuring unit is provided for each shaft for determining the
respective rotational shaft velocity and/or the respective position
of the shafts with respect to one another, the rotational velocity
measuring units each being operatively connected with the
corresponding control device.
13. Gear pump according to claim 4, wherein a rotational velocity
measuring unit is provided for each shaft for determining the
respective rotational shaft velocity and/or the respective position
of the shafts with respect to one another, the rotational velocity
measuring units each being operatively connected with the
corresponding control device.
14. Gear pump according to claim 1, wherein the power ratio between
the two driving units can be adjusted between 0.05 and 1.
15. Gear pump according to claim 4, wherein the power ratio between
the two driving units can be adjusted between 0.05 and 1.
16. Gear pump according to claim 1, wherein a computer unit is
connected to the data line.
17. A method of operating a gear pump which has two mutually
meshing gears supported on respective shafts driven by respective
driving units, said method comprising: controlling the driving
units by respective control units operably connected by a data line
to thereby precisely coordinate the angular velocities to avoid
excess torque forces on teeth of the meshing gears while preventing
a lifting off of surfaces of the teeth, during pumping
operations.
18. A method according to claim 17, wherein the control units are
constructed symmetrically with respect to one another.
19. A method according to claim 17, wherein a power converter is
provided for each driving unit, each power converter being
operatively connected with a respective driving unit, and wherein a
control device is provided in each control unit for generating
control signals which act upon the corresponding power converters,
the data line existing between the two control units being guided
to the respective control devices.
20. A method according to claim 19, wherein the power converter
output signals, or signals proportional thereto, are returned into
the corresponding control device.
21. A method according to claim 17, wherein the driving units are
of the asynchronous machine type.
22. A method according to claim 21, wherein the power converters
are of the inverse rectifier type for generating current, voltage
and frequency.
23. A method according to claim 17, wherein a rotational velocity
measuring unit is provided for each shaft for determining the
respective rotational shaft velocity and/or the respective position
of the shafts with respect to one another, the rotational velocity
measuring units each being operatively connected with the
corresponding control device.
24. A method according to claim 17, wherein the power ratio between
the two driving units can be adjusted between 0.05 and 1.
25. A method according to claim 17, wherein a computer unit is
connected to the data line.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The present invention relates to a gear pump having two
mutually meshing gears which are each assigned to a shaft and which
are each driven by means of a driving unit, the driving units each
being drivable by a control unit such that the shafts rotate at a
definable rotational velocity.
[0002] Normally, gear pumps are driven by a single shaft which
extends out of the pump casing. In cases with very high torques or
when the flow medium is charged with fillers, two-shaft
arrangements are occasionally also used in order to protect the
tooth surfaces from wear or excess strain.
[0003] Known multishaft drives include timing gears which ensure
that the tooth surfaces do not come in contact with one another. In
the case of the known multishaft drives, a single driving unit is
used, the force distribution onto the individual shafts taking
place by means of the engaging gears by way of the above-mentioned
timing gear.
[0004] Furthermore, a teaching is known from German Patent Document
DE-32 30 550 C2 in which a two-shaft drive is described which has
two driving units. In this case, direct-current motors are used
with a control unit which is based on current measurements in the
exciting circuit of both driving units and on a rotational velocity
measurement in the case of one driving unit. In this known
teaching, a desired rotational velocity and a desired power ratio
can be defined.
[0005] The last-mentioned driving concept has the disadvantage
that, as the result of the rotational velocity monitoring taking
place only on one side, in the event of a clutch, transmission or
pump gearing damage, the line in which the rotational velocity is
not monitored may cause consequent damage by endeavoring to reach
the desired power. Furthermore, the power ratio can be adjusted
only in a narrow range of from 0.5 to 1. Finally, this system is
not suitable for appropriately detecting and taking into account
torque pulsations because of the intervention point shifting on the
intervention line, because of minimal gearing inaccuracies or
differences in the rigidities of the engine mounting and
transmission mounting.
[0006] It is therefore an object of the present invention to
provide a gear pump which does not have the above-mentioned
disadvantages.
[0007] This object is achieved by providing a gear pump of the
above noted type, wherein the control units are operably connected
by way of a data line. Further advantageous features of preferred
embodiments of the present invention are described below and in the
claims.
[0008] Preferred embodiments of the invention have the following
advantages. In that a completely symmetrical structure for the
control units for controlling the driving units is provided and, in
addition, a fast data transmission is provided between the two
control devices contained in the control units, it is achieved
that, despite possible torque pulses on the shafts, the tooth
surfaces will neither lift off, nor can an excess torque which is
too high be transmitted by way of the tooth surfaces.
[0009] Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The single drawing FIGURE is a schematic representation of a
gear pump having two identical control units according to preferred
embodiments of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0011] The drawing FIGURE schematically depicts a gear pump having
a two-shaft drive and two control units SE1 and SE2 according to
the invention. The gear pump has two mutually meshing gears Z1 and
Z2 which are assigned to two different gear shafts W1 and W2. The
gears Z1 and Z2 and the shafts W1 and W2 are contained in a pump
casing G. The shafts W1 and W2 extend to the outside and the
projecting ends of the shafts W1 and W2 are each coupled with a
driving unit AE1 and AE2.
[0012] According to the invention, the control units SE1 and SE2
have a symmetrical construction and include one control device KE1
and KE2 respectively, one inverse rectifier WR1 and WR2
respectively as a power converter, and one rotational velocity
measuring unit DME1 and DME2 respectively as measuring units which
are each connected with a signal generator of the known type
mounted on the shafts W1 and W2. In the rotational velocity
measuring units DME1 and DME2, the signal measured in the signal
generator is processed for the determination of the angular
velocities .omega.1 and .omega.2, these then being transmitted to
the control devices KE1 and KE2.
[0013] In the control devices KE1 and KE2, the respective control
signals SS1 and SS2 are generated for controlling the respective
inverse rectifiers WR1 and WR2. For this purpose, in addition to
the angular velocity .omega.1 and .omega.2, output signals for the
driving units AE1 and AE2 are also used which are generated by the
inverse rectifier WR1 and WR2, whereby possible nonlinearities or
asymmetries of the inverse rectifiers WR1 and WR2 are automatically
compensated.
[0014] In a preferred embodiment of the invention, the driving
units AE1 and AE2 are of the electric asynchronous machine type
(Rolf Fischer, "Electric Machines", 5th Edition, Carl Hanser
Verlag, 1983, Pages 170 to 260). The output signals generated by
the inverse rectifier WR1 and WR2 are indicated in the drawing
figure by U1 and U2 for the electric voltage, and by I1 and I2 for
the electric current and by F1 and F2 for the frequency.
[0015] As mentioned above, the output signals U1, I1, F1 and U2,
I2, F2 are returned into the control device KE1 and KE2 for a
precise adjustment. This provides a first internal control circuit
for adjusting the rotational velocity of the shafts W1 and W2.
Specifically, if the driving units AE1 and AE2 are conceived as
electromechanical converters, the voltage frequencies F1 and F2 are
imaged on the angular velocities .omega.1 and .omega.1, and the
voltages U1 and U2 and currents I1 and I2 are imaged on
corresponding driving torques (vector drives) . Another control
circuit is created by measuring the rotational shaft velocity by
means of rotational velocity measuring units DME1 and DME2 and
returning the measured signals into the respective control devices
KE1 and KE2. In the context of the present invention, this second
control circuit will be called an external control circuit.
[0016] According to the invention, a fast data line DL, preferably
in the form of a data bus, is provided between the two control
units SE1 and SE2, by way of which the angular velocities .omega.1
and .omega.2 of the two shafts W1 and W2 and the position of the
gears Z1 and Z2 can be precisely coordinated or adjusted with
respect to one another. The data line DL is provided so that
angular velocity differences can be reliably processed within the
control units SE1 and SE and that, despite possible torque pulses,
neither a lifting-off of the tooth surfaces, which are to remain in
contact, is caused, nor is an excess torque, which is too high,
transmitted by way of the tooth surfaces.
[0017] In another embodiment of the invention, it is provided that
a computer unit is connected to the data line DL constructed as a
data bus, by means of which computer unit a rotational velocity
adjustment can, for example, take place, particularly in connection
with other process components, with which the gear pump is
connected.
[0018] The foregoing disclosure has been set forth merely to
illustrate the invention and is not intended to be limiting. Since
modifications of the disclosed embodiments incorporating the spirit
and substance of the invention may occur to persons skilled in the
art, the invention should be construed to include everything within
the scope of the appended claims and equivalents thereof.
* * * * *