U.S. patent application number 14/917211 was filed with the patent office on 2016-08-04 for variable output centrifugal pump.
This patent application is currently assigned to EATON CORPORATION. The applicant listed for this patent is EATON CORPORATION. Invention is credited to Martin A. Clements.
Application Number | 20160222968 14/917211 |
Document ID | / |
Family ID | 52629080 |
Filed Date | 2016-08-04 |
United States Patent
Application |
20160222968 |
Kind Code |
A1 |
Clements; Martin A. |
August 4, 2016 |
VARIABLE OUTPUT CENTRIFUGAL PUMP
Abstract
A variable output pump assembly includes an input drive member
and a primary pump member operatively driven thereby. A second
drive member supplements the pump assembly. A magnetic coupling is
interposed between the input drive member and the second drive
member to variably drive the pump assembly.
Inventors: |
Clements; Martin A.; (North
Royalton, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EATON CORPORATION |
Cleveland |
OH |
US |
|
|
Assignee: |
EATON CORPORATION
Cleveland
OH
|
Family ID: |
52629080 |
Appl. No.: |
14/917211 |
Filed: |
September 4, 2014 |
PCT Filed: |
September 4, 2014 |
PCT NO: |
PCT/US2014/054026 |
371 Date: |
March 7, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61873929 |
Sep 5, 2013 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 13/028 20130101;
F04D 13/024 20130101; F04D 1/06 20130101; F04B 49/20 20130101; F04D
13/06 20130101; F04D 15/0066 20130101 |
International
Class: |
F04D 13/06 20060101
F04D013/06; F04D 1/06 20060101 F04D001/06 |
Claims
1. A variable output pump assembly comprising: an input drive
member; a primary pump member operatively driven by the input drive
member; a second drive member; and a variable torque coupling
interposed between the input drive member and the second drive
member to vary speed output of the second drive member.
2. The variable output pump assembly of claim 1 wherein the
coupling is a variable magnetic coupling interface between the
input drive member and the second drive member.
3. The variable output pump assembly of claim 2 wherein the
magnetic coupling interface includes a magnet and a
magnet/ferro-magnetic member in spaced relation and the spacing
therebetween is selectively altered to vary the magnetic coupling
strength therebetween.
4. The variable output pump assembly of claim 3 wherein one of the
magnet and magnet/ferro-magnetic member is operatively connected to
an actuator that selectively moves the one of the magnet and
magnet/ferro-magnetic member toward and away from the other of the
magnet and magnet/ferro-magnetic member.
5. The variable output pump assembly of claim 4 wherein the input
drive member is connected to the primary pump member which includes
a primary impeller, and a secondary pump member operatively driven
by the second drive member at a speed responsive to the
coupling.
6. The variable output pump assembly of claim 5 further comprising
a ring gear of a planetary gear assembly also operatively connected
to the input drive member for rotation therewith.
7. The variable output pump assembly of claim 6 further comprising
a planetary gear operatively driven by the ring gear such that the
secondary pump member that includes a secondary impeller
operatively associated with the planetary gear assembly rotates at
a different rotational speed.
8. The variable output pump assembly of claim 7 wherein the carrier
receives one of the magnet and the magnet/ferro-magnetic member and
a fixed housing assembly receives the other of the magnet and
magnet/ferro-magnetic member.
9. The variable output pump assembly of claim 8 wherein the
planetary gear assembly includes at least one planetary gear that
receives a rotational drive input from the ring gear, and drives a
sun gear in response thereto.
10. The variable output pump assembly of claim 9 wherein the
secondary impeller has an inlet receiving output flow from an
outlet of the primary impeller.
11. The variable output pump assembly of claim 2 wherein the
magnetic coupling interface includes a magnet and a
magnet/ferro-magnetic member, where one of the magnet and
magnet/ferro-magnetic material is located on a first portion of a
planetary gear arrangement.
12. The variable output pump assembly of claim 11 wherein the other
of the magnet and magnet/ferromagnetic material is located on a
second portion of the planetary gear arrangement.
13. The variable output pump assembly of claim 11 wherein the
magnet is located on the transmission housing and the
magnet/ferro-magnetic material is on the first portion of the
planetary gear arrangement.
14. The variable output pump assembly of claim 6 wherein magnet is
located on a first carrier of the planetary gear arrangement and
the magnet/ferro-magnetic material is operatively associated with a
planet of a second carrier.
15. The variable output pump assembly of claim 14 wherein the
planet of the second carrier is operatively associated with a
pinion gear to supplement rotation of the input drive member.
16. The variable output pump assembly of claim 15 further
comprising an actuator that selectively advances and retracts the
magnet/ferro-magnetic material of the planet toward the magnet of
the first carrier.
17. A method of varying speed output in a drive transmission
assembly comprising: providing a first drive member; providing a
second drive member; positioning a magnetic coupling between the
first drive member and the second drive member to selectively vary
the speed output of the second drive member relative to the first
drive member.
18. The method of claim 17 wherein the magnetic coupling
positioning step placing one of a magnet and magnet/ferro-magnetic
member in spaced relation.
19. The method of claim 18 wherein the spacing between the magnet
and magnet/ferro-magnetic member is selectively altered to vary the
magnetic coupling strength therebetween.
20. The method of claim 20 further including selectively moving one
of the magnet and magnet/ferro-magnetic member toward and away from
the other of the magnet and magnet/ferro-magnetic member.
21. The method of claim 17 further comprising providing a primary
pump member and driving an input shaft of the primary pump member
via the first drive member.
22. The method of claim 21 further comprising providing a secondary
pump member and operatively driving the secondary pump member via
the second drive member at a speed responsive to the magnetic
coupling.
Description
BACKGROUND
[0001] The present disclosure relates to a pump, pump assembly, or
pump system, and an associated method of magnetically coupling
between an input drive member and an output driven member. It finds
particular application in conjunction with a variable output pump,
for example a centrifugal pump, that finds specific use in a fuel
pump application, and will be described with reference thereto.
However, it is to be appreciated that the present exemplary
embodiment is also amenable to other like applications that
encounter similar problems or require similar solutions.
[0002] High speed centrifugal (HSC) pumps typically encounter two
problem areas when attempting to apply them to main engine fuel
pump applications. First, at low starting speeds (for the engine)
the centrifugal pump does not produce sufficient pressure to supply
the fuel system for the start function. Second, once running, the
centrifugal pump tends to over-generate pressure at operating
conditions such as idle and cruise thereby wasting energy and
increasing system operating temperatures.
[0003] This disclosure remedies both of these problems in a simple,
reliable, effective, and inexpensive manner.
BRIEF DESCRIPTION
[0004] A variable output pump assembly includes an input drive
member and a primary pump member operatively driven thereby. A
second drive member supplements the pump assembly. A coupling is
interposed between the input drive member and the second drive
member to variably drive the pump assembly member.
[0005] The coupling is preferably a variable magnetic coupling
interface between the input drive member and the second drive
member.
[0006] The magnetic coupling interface includes a magnet and a
magnet/ferro-magnetic member in spaced relation and the spacing
therebetween is selectively altered to vary the magnetic coupling
strength therebetween.
[0007] A primary advantage is the ability to reduce energy needs
during certain operating conditions (e.g., cruise and idle).
[0008] Another benefit is associated with limiting the temperature
increase to the system.
[0009] Another advantage is efficiently transmitting torque to the
pump assembly.
[0010] Another benefit resides in adding normally lost torque to
the output shaft and thereby improve torque transmission
capability.
[0011] Still another advantage is associated with being able to
generate additional pressure at desired operating conditions (e.g.,
engine start and take-off), and once running, to decrease the
pressure.
[0012] Still other benefits and advantages will become apparent
those skilled in the art after reading and understanding the
following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic representation of a first embodiment
of a variable output centrifugal pump assembly.
[0014] FIG. 2 is a table providing exemplary characteristics of the
variable output centrifugal pump assembly of FIG. 1.
[0015] FIG. 3 is a schematic representation of a second embodiment
of a variable output centrifugal pump assembly.
[0016] FIG. 4 is a schematic view of the FIG. 3 embodiment taken
generally along the lines 4-4 of FIG. 3.
[0017] FIG. 5 is a schematic view of the embodiment of FIG. 3 taken
generally along the lines 5-5 of FIG. 3.
DETAILED DESCRIPTION
[0018] With reference to FIG. 1, a variable output pump, pump
assembly, or pump system (which terms may be used interchangeably
herein), and more specifically a variable output centrifugal pump
system, 100 is shown. A centrifugal pump 110 includes a fluid inlet
112 so that fluid (such as jet fuel for use in an aircraft engine,
although this use is not intended to be limiting) is supplied to a
primary impeller 114 rotatably received in housing 116. The primary
impeller 114 is driven by an input drive or drive shaft 118
rotating at a rotational speed .omega..sub.ring as is conventional
in the art and thus rotates at the same rotary speed
.omega..sub.ring as the input drive. The primary impeller 114
imparts energy to the fluid (e.g., increases the pressure of the
fluid) which pressurized fluid exits generally radially from the
primary impeller.
[0019] In addition, a secondary impeller 130 receives the
pressurized fluid exiting the primary impeller 114 and imparts
further energy to the fluid (again, further increases the pressure
of the fluid). The secondary impeller 130 is schematically
illustrated as part of the rotating housing 116 that receives the
primary impeller 114, although the secondary impeller and housing
could be separate components as will be readily recognized by one
skilled in the art. The housing 116 and thus the secondary impeller
130 rotate at a same rotary speed .omega..sub.sun whereby the
additional energy is added to the fluid before the pressurized
fluid enters into a radial diffuser/collector (not shown).
[0020] The rotational speed of the secondary impeller 130 may be
varied relative to the input drive shaft 118 to vary the amount of
additional energy (additional pressure) added to the fluid. In a
first preferred arrangement, this variable output is achieved with
a variable magnetic coupling interface, such as a magnetically
coupled planetary gear transmission 140, between the input drive
shaft 118 and a secondary drive member 142 such that these drive
components 118 and 142 (shown in a preferred concentric
arrangement) can rotate at different rotational speeds. The
magnetically coupled planetary gear transmission 140 is operatively
connected to the input drive and configured for or capable of
transmitting a variable speed drive to the secondary impeller 130.
That is, depending on the gearing and the amount of drive torque
transmitted through the magnetically coupled planetary gear
transmission 140, the secondary impeller 130 will rotate at the
same or a different rotational speed as the input drive 118, and
can be easily transitioned to a different rotational speed as will
become apparent below.
[0021] More particularly, in one arrangement, the magnetic coupling
140 includes a planetary gear set carrier 148 that varies the
output speed of a sun gear 146 which is attached to the secondary
impeller 130 via the secondary drive member 142. The torque balance
of the secondary impeller load and magnetic coupling strength (as
carried through the planetary gear ratio) sets the output
rotational speed of the secondary impeller 130 and thus its level
of output pressure. Control of the rotational speed of the
secondary impeller 130 is achieved by varying an air gap 160
between a movable magnet 162 that is selectively moved by actuator
164 (e.g., slides along a linear axis that in the exemplary
embodiment is parallel to the rotational axis of the input drive
and the planetary gear set carrier 148). The actuator advances and
retracts the magnet 162 relative to a magnetically coupled carrier
148 that includes a magnet or ferro-magnetic material 166
operatively associated with planets or planet gears 168 received in
the gear set carrier 148. The planets 168 are, in turn, operatively
engaged with the sun gear 146 that is joined to the secondary drive
member or hollow shaft 142 (received around the input drive shaft
118) to drive the housing 116 and secondary impeller 130. The
spacing or air gap 160 between the magnet 162 and the
magnet/ferro-magnetic material 166 associated with the planets
determines the amount of rotational torque that is transferred
between the ring gear 144 (rotating at the same rotational speed
.omega..sub.ring as the input drive) and the planets 168. Thus, if
the air gap 160 is small, the magnetic attraction is higher and an
increased ratio of the rotational speed is transferred to the
planets 168 when compared to a larger air gap which results in a
reduced magnetic force between the magnet 162 and the
magnet/ferro-magnetic material 166 attached to or part of carrier
148, and likewise a reduced ratio of the rotational speed
transferred to the planets. Thus, the rotational speed
.omega..sub.sun of the planets 168, sun gear 146 (operatively
driven by the planets 168), and consequently the secondary drive
shaft 142 (operatively driven by the sun gear) can be the same as
the rotational speed .omega..sub.ring of the input drive 118, or
may be different, depending on the amount of torque transfer
through the magnetic coupling achieved by varying the air gap 160
between the actuated magnet 162 and the magnet/ferro-magnetic
material 166.
[0022] Changing the magnetic coupling air gap 160 results in either
a speed up or slow down of the rotational speed .omega..sub.sun of
the secondary impeller 130 relative to the rotational speed
.omega..sub.ring of the input drive 118. The magnetic coupling
mechanism 140 is preferred in this application because the speed
control is readily achieved without adverse or ill failure mode
effects that are potentially associated with a friction type clutch
mechanism.
[0023] As can be seen from FIG. 2, changing the spacing of the
magnetic coupling air gap 160 results in speeding up or slowing
down of the rotational speed .omega..sub.sun of the secondary
impeller 130 relative to the rotational speed .omega..sub.ring of
the input drive 118. Therefore, at engine start conditions, the air
gap 160 is reduced or minimized and the secondary impeller 130 can
turn sufficiently fast to achieve the desired fuel system pressure
for engine start. Likewise, at engine idle and cruise speeds where
high system pressure may not be required, the air gap 160 is
increased or maximized so that the secondary impeller 130 can be
significantly slowed to minimize pump output pressure which leads
to minimization of power of the input drive 118 shaft and less fuel
system heat build-up. At take-off, the air gap 160 is
reduced/minimized and the speed of the secondary impeller 130 is
increased by minimizing the air gap 160 to provide maximized pump
pressure output to meet fuel system pressure needs.
[0024] A generally related concept of a magnetic coupling interface
being used to vary the speed in a transmission assembly and, for
example, a transmission assembly described in connection with one
specific end use, namely a centrifugal pump assembly, is shown in a
second exemplary embodiment of FIGS. 3-5. Again, there is a desire
to efficiently and variably transmit torque to an output shaft, and
preferably provide variable speed as a supplement or secondary
drive input to a pump driven by a primary input. One manner of
achieving this is to use a magnetic coupling, and more specifically
another version of a variable speed planetary gear transmission is
illustrated and described herein. This second exemplary arrangement
not only varies the speed of the output shaft (relative to the
input) but also incorporates features to add "normally" lost torque
in such a device to the output shaft and thereby improve torque
transmission capability.
[0025] A variable speed planetary gear set 200 is a part of the
magnetic coupling illustrated in FIGS. 3-5. One potential use of
the variable speed planetary gear set 200 is in connection with a
variable output centrifugal pump 202 that includes a rotating
impeller 204 that raises pressure of the fluid between an inlet 206
and outlet 208. The variable centrifugal pump assembly 202 includes
a connection between a drive member and the impeller to pressurize
the fluid in the system. Here, however, details of the variable
speed planetary gear set 200 are different than that shown and
described in connection with the embodiment of FIGS. 1 and 2.
[0026] The input drive 210 has a rotational speed .omega..sub.s and
drives or rotates a sun gear 212 at this same rotational speed
.omega..sub.s. The sun gear 212, in turn, drives one or more
planets 214 which drive a ring gear 216 that rotates at a
rotational speed .omega..sub.r in a manner generally known by an
ordinarily skilled artisan. In addition, the planets 214 are
operatively associated with a first carrier 220 that is, in turn,
operatively associated with an output drive 222. Controlling a
rotational speed .omega..sub.r of the ring gear 216 drives the
output drive 222 at a desired rotational speed .omega..sub.c.
[0027] The ring gear 216 includes a portion of a magnetic coupling
230, namely, magnets 232 are disposed in circumferentially spaced
arrangement along a face of the ring gear 216. In addition, the
magnetic coupling 230 includes one or more planets 234 that each
have circumferentially spaced magnets or ferro-magnetic material
236. An air gap 240 is provided between the planets 234 and the
magnets 232 of the ring gear 216. The air gap 240 is selectively
varied, which varies the amount of torque transferred between these
components, by axially moving the planets 234 toward and away from
the magnets 232 of the ring gear 216. Actuator 242 axially advances
and retracts the planets 234 via a second carrier 244. A spline or
keyed connection 246 limits the movement of the second carrier 244
(and thus the planets 234) in an axial direction. As the air gap
240 is reduced or minimized, a greater amount of torque from the
ring gear 216 is transferred to the planets 234. The torque imposed
on the planets 234 is then transferred to pinion gear 250 of the
first carrier 220 and thus adds torque to the output at the
rotational speed .omega..sub.c of the output drive 222 (which is
the drive member for the impeller 204).
[0028] An intentional slipping of the ring gear 216 is used to vary
a resultant rotational speed .omega..sub.c of the first carrier
220. Specifically, controlling the rotational speed .omega..sub.r
of the ring gear 216 drives the first carrier 220 and likewise the
output drive 222 at a desired rotational speed .omega..sub.c. More
particularly, the pinion gear 250 of the first carrier 220 drives
planets 234 of the second carrier 244 which mesh with the pinion
gear 250. This varies the resultant speed of the first carrier 220
and thus the output drive 222. The magnetic coupling 230 flexibly
transmits torque between the ring gear 216 and the planets 234
associated with the second carrier 244. If the tangential velocity
of the magnets 232 of the magnetic coupling 230 connected to the
ring gear 216 is greater than the tangential velocity of the
magnets/ferro-magnetic material 236 connected to the planets 234,
torque from the ring gear 216 will be added to the output drive 222
via the meshing of the planets 234 with the pinion gear 250.
[0029] The speed of the output shaft 222 is set by the amount of
torque used to hold or slow down the ring gear 216. This torque is
that which is transmitted to the output drive 222 via the flexible
magnetic coupling 230. The amount of torque transmission through
the magnetic coupling 230 is a function of the air gap 240 between
the halves of the magnetic pair. Thus, by varying the air gap 240
via the actuator 242, the rotational speed of the output shaft 222
relative to the input shaft 210 can be varied. The air gap 240 is
modulated by axial movement of the second carrier assembly 244
along the splined interface 246 with the transmission housing. The
spline 246 allows the second carrier assembly 244 to slide axially
while resisting the torque applied to hold the second carrier from
rotating. The actuator 242 is used to slide the second carrier
assembly 244 and thus set the air gap 240. An assortment of open
and closed loop controls can then be imparted to provide the desire
speed outcome for the transmission.
[0030] The present disclosure also contemplates that the system may
employ an electromagnetic arrangement to achieve a desired speed
ratio or alter the speed ratio during operation. For example,
rather than employing permanent magnets and/or ferro-magnetic
materials that vary the strength of the magnetic field by varying
the distance between the magnetic components (e.g., using the
actuator in the above-described embodiments), the strength of the
magnetic field in an electromagnetic arrangement can be easily
varied by changing the amount of electric current through the wire
or coil. Of course, further details of the structure and operation
of electromagnets are known to those skilled in the art and will
not be described herein for purposes of brevity. The use of an
electromagnetic arrangement, however, is yet another type of
magnetic coupling that achieves the desired control of the magnetic
field and likewise the associated variation in the speed ratio and
torque of the output shaft of above-described planetary gear
transmission, which in one embodiment is used in a centrifugal pump
assembly.
[0031] A first item of the present disclosure includes a variable
output pump assembly that has an input drive member, a primary pump
member operatively driven by the input drive member, a second drive
member, and a variable torque coupling interposed between the input
drive member and the second drive member to vary speed output of
the second drive member.
[0032] A second item of the present disclosure includes the
coupling as a variable magnetic coupling interface between the
input drive member and the second drive member, and the second item
may be used in combination with the first item.
[0033] A third item of the present disclosure includes the magnetic
coupling interface having a magnet and a magnet/ferro-magnetic
member in spaced relation and the spacing therebetween is
selectively altered to vary the magnetic coupling strength
therebetween, and the third item may be used in combination with
either or both of the first and second items.
[0034] A fourth item of the present disclosure includes one of the
magnet and magnet/ferro-magnetic member that is operatively
connected to an actuator that selectively moves the one of the
magnet and magnet/ferro-magnetic member toward and away from the
other of the magnet and magnet/ferro-magnetic member, and the
fourth item may be used in combination with any one or more of the
first through third items.
[0035] A fifth item of the present disclosure includes the input
drive member connected to the primary pump member which includes a
primary impeller, and a secondary pump member operatively driven by
the second drive member at a speed responsive to the coupling, and
the fifth item may be used in combination with any one or more of
the first through fourth items.
[0036] A sixth item of the present disclosure includes a ring gear
of a planetary gear assembly also operatively connected to the
input drive member for rotation therewith, and the sixth item may
be used in combination with any one or more of the first through
fifth items.
[0037] A seventh item of the present disclosure includes a
planetary gear operatively driven by the ring gear such that the
secondary pump member that includes a secondary impeller
operatively associated with the planetary gear assembly rotates at
a different rotational speed, and the seventh item may be used in
combination with any one or more of the first through sixth
items.
[0038] An eighth item of the present disclosure includes the
carrier receiving one of the magnet and the magnet/ferro-magnetic
member, and a fixed housing assembly receives the other of the
magnet and magnet/ferro-magnetic member, and the eighth item may be
used in combination with any one or more of the first through
seventh items.
[0039] A ninth item of the present disclosure includes the
planetary gear assembly having at least one planetary gear that
receives a rotational drive input from the ring gear, and drives a
sun gear in response thereto, and the ninth item may be used in
combination with any one or more of the first through eighth
items.
[0040] A tenth item of the present disclosure includes an inlet of
the secondary impeller receiving output flow from an outlet of the
primary impeller, and the tenth item may be used in combination
with any one or more of the first through ninth items.
[0041] An eleventh item of the present disclosure includes the
magnetic coupling interface having a magnet and a
magnet/ferro-magnetic member, where one of the magnet and
magnet/ferro-magnetic material is located on a first portion of a
planetary gear arrangement, and the eleventh item may be used in
combination with any one or more of the first through tenth
items.
[0042] A twelfth item of the present disclosure includes the other
of the magnet and magnet/ferromagnetic material located on a second
portion of the planetary gear arrangement, and the twelfth item may
be used in combination with any one or more of the first through
eleventh items.
[0043] A thirteenth item of the present disclosure includes a
magnet located on the transmission housing and the
magnet/ferro-magnetic material located on the first portion of the
planetary gear arrangement, and the thirteenth item may be used in
combination with any one or more of the first through twelfth
items.
[0044] A fourteenth item of the present disclosure includes a
magnet located on a first carrier of the planetary gear arrangement
and the magnet/ferro-magnetic material operatively associated with
a planet of a second carrier, and the fourteenth item may be used
in combination with any one or more of the first through thirteenth
items.
[0045] A fifteenth item of the present disclosure includes the
planet of the second carrier operatively associated with a pinion
gear to supplement rotation of the input drive member, and the
fifteenth item may be used in combination with any one or more of
the first through fourteenth items.
[0046] A sixteenth item of the present disclosure includes an
actuator that selectively advances and retracts the
magnet/ferro-magnetic material of the planet toward the magnet of
the first carrier, and the sixteenth item may be used in
combination with any one or more of the first through fifteenth
items.
[0047] A seventeenth item of the present disclosure is a method of
varying speed output in a drive transmission assembly that includes
providing a first drive member, providing a second drive member,
and positioning a magnetic coupling between the first drive member
and the second drive member to selectively vary the speed output of
the second drive member relative to the first drive member.
[0048] An eighteenth item of the present disclosure includes
placing one of a magnet and magnet/ferro-magnetic member in spaced
relation in the magnetic coupling positioning step, and the
eighteenth item may be used in combination with the seventeenth
item.
[0049] A nineteenth item of the present disclosure includes
selectively altering the spacing between the magnet and
magnet/ferro-magnetic member to vary the magnetic coupling strength
therebetween, and the nineteenth item may be used in combination
with either or both of the seventeenth and eighteenth items.
[0050] A twentieth item of the present disclosure includes
selectively moving one of the magnet and magnet/ferro-magnetic
member toward and away from the other of the magnet and
magnet/ferro-magnetic member, and the twentieth item may be used in
combination with any one or more of the seventeenth through
nineteenth items.
[0051] A twenty-first item of the present disclosure includes
providing a primary pump member and driving an input shaft of the
primary pump member via the first drive member, and the
twenty-first item may be used in combination with any one or more
of the seventeenth through twentieth items.
[0052] A twenty-second item of the present disclosure includes
providing a secondary pump member and operatively driving the
secondary pump member via the second drive member at a speed
responsive to the magnetic coupling, and the twenty-second item may
be used in combination with any one or more of the seventeenth
through twenty-first items.
[0053] The disclosure has been described with reference to
exemplary embodiments. Obviously, modifications and alterations
will occur to others upon reading and understanding the preceding
detailed description. For example, the description of a magnet on
one component cooperating with a magnet or ferro-magnetic material
on another component could be reversed. It is intended that the
exemplary embodiments be construed as including all such
modifications and alterations insofar as they come within the scope
of the appended claims or the equivalents thereof.
* * * * *