U.S. patent number RE48,623 [Application Number 16/364,473] was granted by the patent office on 2021-07-06 for viscous clutch with return bore through rotor.
This patent grant is currently assigned to HORTON, INC.. The grantee listed for this patent is Horton, Inc.. Invention is credited to Bastian Brand, Scott Miller, Thomas Schmidt.
United States Patent |
RE48,623 |
Schmidt , et al. |
July 6, 2021 |
Viscous clutch with return bore through rotor
Abstract
A viscous clutch (20) includes a housing assembly (28), a rotor
assembly (26), a reservoir (38) to hold a supply of a shear fluid,
a working chamber (40) operatively positioned between the housing
assembly and the rotor assembly, and a fluid return bore (26-1B)
that optionally extends radially through at least an outer diameter
portion of the rotor assembly to the working chamber. Selective
introduction of the shear fluid to the working chamber facilitates
selective torque transmission between the housing assembly and the
rotor assembly. The fluid return bore can form at least a portion
of a fluid return path (50) from the working chamber to the
reservoir.
Inventors: |
Schmidt; Thomas (St. Paul,
MN), Brand; Bastian (Schonungen, DE), Miller;
Scott (Edina, MN) |
Applicant: |
Name |
City |
State |
Country |
Type |
Horton, Inc. |
Roseville |
MN |
US |
|
|
Assignee: |
HORTON, INC. (Roseville,
MN)
|
Family
ID: |
1000005490306 |
Appl.
No.: |
16/364,473 |
Filed: |
March 26, 2019 |
PCT
Filed: |
September 20, 2013 |
PCT No.: |
PCT/US2013/060889 |
371(c)(1),(2),(4) Date: |
March 13, 2015 |
PCT
Pub. No.: |
WO2014/047430 |
PCT
Pub. Date: |
March 27, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
61704457 |
Sep 22, 2012 |
|
|
|
Reissue of: |
14428255 |
Sep 20, 2013 |
9624988 |
Apr 18, 2017 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H
47/00 (20130101); F16H 47/065 (20130101); F16D
35/024 (20130101); F16D 35/005 (20130101); F16D
35/00 (20130101); F16D 2300/0212 (20130101) |
Current International
Class: |
F16D
35/00 (20060101); F16D 35/02 (20060101); F16H
47/06 (20060101); F16H 47/00 (20060101) |
References Cited
[Referenced By]
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WO |
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Other References
Japanese Office Action for corresponding JP application No.
2015-533216, dated Jan. 4, 2017, 4 pages. cited by applicant .
Notification of Reasons for Refusal in counterpart Japanese Patent
Application No. 2016-170729 dated Jul. 7, 2017 (4 pages). cited by
applicant .
International Search Report and Written Opinion from PCT
Application Serial No. PCT/US2013/060889, dated Dec. 17, 2013, 13
pages. cited by applicant .
Extended European Search Report for EP Application No. 15178814.4,
dated Jan. 4, 2016, 7 pages. cited by applicant.
|
Primary Examiner: English; Peter C
Attorney, Agent or Firm: Westman, Champlin & Koehler, P.
A.
Claims
The invention claimed is:
1. A viscous clutch comprising: .Iadd.a rotationally fixed journal
bracket having a shaft portion; .Iaddend. a housing assembly; a
rotor assembly .Iadd.that includes a disk and a bearing hub
connected to the disk for co-rotation therewith, wherein the
bearing hub extends beyond the housing assembly in a direction away
from the journal bracket to provide a mounting location for an
output member, and wherein the rotor assembly is rotatably
supported on the shaft portion.Iaddend.; a reservoir to hold a
supply of a shear fluid, the reservoir carried by the housing
assembly; a reservoir cover defining a portion of a boundary of the
reservoir; a working chamber operatively positioned between the
housing assembly and the rotor assembly, wherein selective
introduction of the shear fluid to the working chamber facilitates
selective torque transmission between the housing assembly and the
rotor assembly; .Iadd.an electromagnetically actuated valve
assembly configured to controllably translate a first valve element
that controls flow of the shear fluid between the reservoir and the
working chamber; an electromagnetic coil assembly located rearward
of the housing assembly, wherein energization of the coil assembly
controls translation of the first valve element, wherein the
reservoir is located in between the electromagnetic coil assembly
and the mounting location for the output member on the bearing hub,
and wherein the valve assembly extends from a location adjacent to
the electromagnetic coil assembly into the reservoir; .Iaddend. an
outlet bore in the reservoir cover to allow the shear fluid out of
the reservoir to the working chamber along a fluid delivery path;
and a fluid return bore that extends radially through at least an
outer diameter portion of the .Iadd.disk of the .Iaddend.rotor
assembly to the working chamber, the fluid return bore forming at
least a portion of a fluid return path from the working chamber to
the reservoir.
.[.2. The viscous clutch of claim 1 and further comprising: an
electromagnetically actuated valve assembly configured to
controllably translate a first valve element that controls flow of
the shear fluid between the reservoir and the working
chamber..].
3. The viscous clutch of claim .[.2.]. .Iadd.1.Iaddend. and further
comprising: a second valve element configured to be actuated
concurrently with the first valve element to further control flow
of the shear fluid between the reservoir and the working
chamber.Iadd., wherein the first and second valve elements are
actuated by a common translating armature.Iaddend..
4. The viscous clutch of claim 1.[.and further comprising:
an.]..Iadd., wherein .Iaddend.the electromagnetic coil assembly
.Iadd.is .Iaddend.positioned adjacent to the housing assembly,
.Iadd.and .Iaddend.wherein the electromagnetic coil assembly
includes first and second windings each having terminals
electrically connectable in a configuration selected from the group
consisting of series and parallel, for operation at different
voltages.
.[.5. The viscous clutch of claim 1, wherein the rotor assembly
comprises: a disk, wherein the fluid return bore extends radially
through at least a portion of the disk; and a bearing hub connected
to the disk for co-rotation therewith, wherein the bearing hub
extends beyond the housing assembly to provide a mounting location
for an output member..].
6. The viscous clutch of claim 1 and further comprising: a pulley
connected to the housing assembly for co-rotation with the housing
assembly.
7. The viscous clutch of claim 1 and further comprising: .[.a
rotationally fixed journal bracket having a shaft portion;.]. a
first set of tapered roller bearings for rotationally supporting
the housing assembly on the shaft portion of the journal bracket;
and a second set of tapered roller bearings for rotationally
supporting the rotor assembly on the shaft portion of the journal
bracket.
8. The viscous clutch of claim 1, wherein the housing assembly
includes a plurality of cooling fins, and wherein the cooling fins
are configured to rotate whenever there is a rotational input to
the viscous clutch.
9. The viscous clutch of claim 1 and further comprising: an
interchangeable pump bore insert positioned at least partially
within the fluid return bore, wherein the inter-changeable pump
bore insert includes a bore in fluid communication with the fluid
return bore.
10. The viscous clutch of claim 9 and further comprising: an access
opening in the housing assembly configured to allow access to the
interchangeable pump bore insert.
11. The viscous clutch of claim 1 and further comprising: a wiper
at an outer diameter portion of the rotor assembly and protruding,
at least partially, into the working chamber.
12. The viscous clutch of claim 11, wherein the wiper is removably
attached to .[.a.]. .Iadd.the .Iaddend.disk of the rotor
assembly.
13. The viscous clutch of claim 1 and further comprising: a flow
guide that traverses the reservoir cover to deliver the shear fluid
from .Iadd.the .Iaddend.fluid return bore of the rotor assembly to
the reservoir along the fluid return path.
14. The viscous clutch of claim 1 and further comprising: .[.a
bearing hub connected to the disk for co-rotation therewith,
wherein the bearing hub extends beyond the housing assembly to
provide a mounting location for an output member; a rotationally
fixed journal bracket having a shaft portion, wherein the bearing
hub extends beyond the housing assembly in a direction away from
the journal bracket;.]. a first bearing set for rotationally
supporting the housing assembly on the shaft portion of the journal
bracket; and a second bearing set for rotationally supporting the
rotor assembly on the shaft portion of the journal bracket.
15. A method for selective torque transmission, the method
comprising: delivering a rotational input to a housing assembly
that carries a reservoir; .Iadd.rotating the housing assembly on a
rotationally fixed mounting shaft with a first bearing set, wherein
the first bearing set is located radially inward from the
reservoir; .Iaddend. selectively delivering a shear fluid to a
working chamber along a fluid delivery path extending from the
reservoir to the working chamber, wherein the fluid delivery path
extends through an outlet bore along a boundary of the reservoir;
transmitting torque to a rotor assembly as a function of volume of
the shear fluid selectively delivered to the working chamber;
.Iadd.rotating the rotor assembly on the rotationally fixed
mounting shaft with a second bearing set; .Iaddend.and returning
the shear fluid from the working chamber to the reservoir along a
fluid return path that extends through a substantially radial bore
through a disk of the rotor assembly.
16. The method of claim 15 and further comprising: providing a
first interchangeable pump bore insert to provide pumping at a
first rate when returning the shear fluid from the working chamber
to the reservoir.
17. The method of claim 16 and further comprising: replacing the
first interchangeable pump bore insert having a bore of a first
size with a second interchangeable pump bore insert having a bore
of a second size that is different from the first size.
18. The method of claim 15 and further comprising: securing a
.Iadd.removably attached .Iaddend.wiper to an outer diameter
portion of the disk adjacent to the substantially radial bore such
that the wiper protrudes into the working chamber.
.[.19. A viscous clutch comprising: a housing assembly; a rotor
assembly; a reservoir to hold a supply of a shear fluid; a working
chamber operatively positioned between the housing assembly and the
rotor assembly, wherein selective introduction of the shear fluid
to the working chamber facilitates selective torque transmission
between the housing assembly and the rotor assembly; a fluid return
bore that extends radially through at least an outer diameter
portion of the rotor assembly to the working chamber, the fluid
return bore forming at least a portion of a fluid return path from
the working chamber to the reservoir; an interchangeable pump bore
insert positioned at least partially within the fluid return bore,
wherein the inter-changeable pump bore insert includes a bore in
fluid communication with the fluid return bore; and an access
opening in the housing assembly configured to allow access to the
interchangeable pump bore insert..].
.[.20. A viscous clutch comprising: a housing assembly; a rotor
assembly including a disk; a reservoir to hold a supply of a shear
fluid; a working chamber operatively positioned between the housing
assembly and the rotor assembly, wherein selective introduction of
the shear fluid to the working chamber facilitates selective torque
transmission between the housing assembly and the rotor assembly; a
fluid return bore that extends radially through at least an outer
diameter portion of the rotor assembly to the working chamber, the
fluid return bore forming at least a portion of a fluid return path
from the working chamber to the reservoir; and a wiper at an outer
diameter portion of the rotor assembly and protruding, at least
partially, into the working chamber, wherein the wiper is removably
attached to the disk of the rotor assembly..].
.Iadd.21. A viscous clutch comprising: a rotationally fixed shaft;
an input assembly rotationally mounted on the shaft; an output
assembly rotationally mounted on the shaft, wherein the output
assembly includes a disk and a bearing hub connected to the disk
for co-rotation therewith, wherein the bearing hub extends beyond a
front of the input assembly to provide a forward-facing mounting
surface; a reservoir to hold a supply of a shear fluid, the
reservoir carried by the input assembly; a reservoir cover attached
to the input assembly, the reservoir cover defining a portion of a
boundary of the reservoir; a working chamber operatively positioned
between the input assembly and the disk of the output assembly; an
outlet bore in the reservoir cover to allow the shear fluid out of
the reservoir to the working chamber along a fluid delivery path;
an additional outlet bore in the reservoir cover to further allow
the shear fluid out of the reservoir to the working chamber along
the fluid delivery path; an electromagnetically actuated valve
assembly including: a first valve element that controls flow of the
shear fluid between the reservoir and the working chamber through
the outlet bore; a second valve element that further controls flow
of the shear fluid between the reservoir and the working chamber
through the additional outlet bore; a first axially-extending rod
that passes through a first rod opening in the input assembly and
that engages the first valve element; a second axially-extending
rod that passes through a second rod opening in the input assembly
and that engages the second valve element; and a translating
armature located rearward of the disk and secured to both the first
and second axially-extending rods, such that the first and second
valve elements are actuatable concurrently in response to magnetic
flux applied to the translating armature; and a fluid return bore
that extends radially through at least an outer diameter portion of
the disk of the output assembly to the working chamber, the fluid
return bore forming at least a portion of a fluid return path from
the working chamber to the reservoir. .Iaddend.
Description
BACKGROUND
The present invention relates to clutches, and more particularly to
viscous clutches.
Viscous clutches are used in a wide variety of automotive
applications, such as to drive fans, pumps and the like, as well as
in other contexts. These clutches typically employ relatively thick
silicone oil (generally called shear fluid or viscous fluid) for
the selective transmission of torque between two rotatable
components. It is possible to engage or disengage the clutch by
selectively allowing the oil into and out of a working area of the
clutch located between input and output members. In a typical
viscous clutch, the rotational input is a rotor disk connected to a
drive shaft or pulley, and the rotational output is a housing or
cover that can be connected to a fan, pump, shaft or other output
element. A valve is used to control the flow of the oil through the
working area between the input and the output. It has become common
for the clutch to be controlled electrically. This has been done to
increase the controllability of the clutch, and to also have the
clutch capable of responding to multiple cooling needs in a
vehicle, such as to respond to coolant temperature, intake air
temperature, air conditioning pressure, and/or oil temperature.
Viscous clutches have been used in the past as a separate device
installed on a rotating pulley on the engine front. Rotational
inputs to the clutch have been traditionally been engine
crankshafts and water pumps. During the past decade, cooling
requirements have been increasing as a result of increasingly
stringent engine emission reduction requirements. During this time,
the use of a belted pulley has become a more common method of
providing an input to the fan clutch, with the belted pulley
(synonymously called a sheave) capable of increasing the fan speed
in order to obtain more cooling air flow for a vehicle's heat
exchanger(s). The belted drive is desirable due to its simplicity,
low cost and ease of obtaining desired rotational speed. Due to the
rotational input to the fan clutch being separated from the water
pump or crankshaft, it is possible for the cooling system engineer
to choose the exact fan speed required to provide the necessary and
desired cooling for a given application.
Examples of viscous clutches include those disclosed in
commonly-assigned U.S. Pat. No. 7,938,240 and PCT Published
Applications WO 2011/062856A3 and WO 2012/024497A3. Further
examples of viscous clutches include those disclosed in U.S. Pat.
Nos. 4,046,239; 6,419,064 and 7,828,529, in U.S. Published Pat.
App. No. 2012/0164002, and in European Published Patent Application
No. EP 2 487 380 A1.
It is therefore desired to provide an alternative clutch
design that is suitable for use with relatively high input speeds
and torque loads, has relatively low mass, and provides relatively
good heat dissipation, among other possible features and benefits.
In addition, or in the alternative, it is desired to provide an
alternative clutch design that is adaptable to a variety of
applications without the need for extensive customization and
whole-clutch re-design, among other possible features and
benefits.
SUMMARY
In one aspect, a viscous clutch includes a housing assembly, a
rotor assembly, a reservoir to hold a supply of a shear fluid, a
working chamber operatively positioned between the housing assembly
and the rotor assembly, and a fluid return bore that optionally
extends radially through at least an outer diameter portion of the
rotor assembly to the working chamber. Selective introduction of
the shear fluid to the working chamber facilitates selective torque
transmission between the housing assembly and the rotor assembly.
The fluid return bore can form at least a portion of a fluid return
path from the working chamber to the reservoir.
In another aspect, considered either in addition to or in the
alternative to the first aspect, a viscous clutch includes a
housing assembly, a rotor assembly, a reservoir to hold a supply of
a shear fluid, a working chamber operatively positioned between the
housing assembly and the rotor assembly, wherein selective
introduction of the shear fluid to the working chamber facilitates
selective torque transmission between the housing assembly and the
rotor assembly, and a pump bore insert having a bore in fluid
communication with a fluid return path extending from the working
chamber to the reservoir.
Persons of ordinary skill in the art will recognize that other
aspects and embodiments of the present invention are possible.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a portion of an embodiment of a
clutch according to the present invention.
FIG. 2 is an enlarged cross-sectional view of a portion of the
clutch of FIG. 1.
FIG. 3 is a cross-sectional view of a pump bore insert suitable for
use with the clutch of FIG. 1.
FIG. 4 is a cross-sectional view of another portion of the clutch,
taken along line 4-4 of FIG. 1.
FIG. 5 is a perspective view of an embodiment of a wiper suitable
for use with the clutch of FIG. 1.
FIG. 6 is a cross-sectional view of an embodiment of a valve
assembly suitable for use with the clutch of FIG. 1.
FIG. 7 is a schematic block diagram of another embodiment of the
valve assembly suitable for use with the clutch of FIG. 1.
FIG. 8 is a schematic block diagram of an embodiment of an
electromagnetic coil assembly suitable for use with the clutch of
FIG. 1.
FIG. 9 is a flow chart of an embodiment of a method of assembling
and using a clutch according to the present invention.
While the above-identified drawing figures set forth one or more
embodiments of the invention, other embodiments are also
contemplated. In all cases, this disclosure presents the invention
by way of representation and not limitation. It should be
understood that numerous other modifications and embodiments can be
devised by those skilled in the art, which fall within the scope
and spirit of the principles of the invention. The figures may not
be drawn to scale, and applications and embodiments of the present
invention may include features and components not specifically
shown in the drawings.
DETAILED DESCRIPTION
The present application claims priority to U.S. Provisional Patent
Application Ser. No. 61/704,457, filed Sep. 22, 2012, which is
hereby incorporated by reference in its entirety.
In general, the present invention relates to a viscous clutch
capable of selectively transmitting a desired torque output from a
provided torque input. The present clutch is "backwards" compared
to most other viscous clutches in that an input member (e.g.,
pulley or sheave) attaches to a housing assembly of the device
rather than to a rotor. In this way, the rotor can be attached to
an output member, such as a fan, and thereby provide an output of
the clutch. Further, the housing assembly connected to the input
member can together provide a rotational input to the clutch.
Advantages of this approach include allowing finned parts (e.g.,
the housing assembly or other input member(s)) to spin at a
relatively high input speed whenever a rotational input is
provided, not just when the output is selectively driven. In that
way, cooling fins of the clutch can more effectively dissipate heat
due to the greater interaction with ambient air that is possible at
higher rotational speeds. Also, a reservoir of the clutch can be
located in the housing assembly, which allows for greater cooling
of the operating or shear fluid (e.g., silicone oil), due to
proximity to an exterior of the clutch and to the cooling fins.
Additionally, attaching the input member (e.g., pulley or sheave)
to the housing can allow elimination of at least a portion of a
center section of the input member, saving a great deal of weight
(mass). Despite a reduced weight (mass), the input member--when
configured as a pulley or sheave--can still provide a relatively
large outer diameter, if desired for particular applications.
In addition or in the alternative, a clutch of the present
invention can include a detachable/interchangeable wiper, which
allows a size of the wiper to be easily changed, to help adjust a
pumping rate of the clutch. Further, a pump bore insert can be used
that is interchangeable to provide different bore passage sizes,
which can also help adjust the pumping rate of the clutch. The
adjustable and interchangeable wiper and pump bore insert features
can help tune the clutch to operate with a variety of output
members (e.g., fans) without requiring complete redesign of the
entire clutch. It also allows the clutch to be tuned more readily
while in the field, rather than just in a factory or
laboratory.
Additional features and benefits of the present invention will be
recognized by those of skill in the art in view of the entirety of
the present disclosure, including the accompanying figures.
FIG. 1 is a cross-sectional view of a portion of an embodiment of a
clutch 20, and FIG. 2 is an enlarged cross-sectional view of a
portion of the clutch 20. Only a portion of the clutch 20 above the
axis of rotation A is shown in FIG. 1, for simplicity. Persons of
ordinary skill in the art will appreciate that portions of the
clutch 20 omitted in FIG. 1 below the axis of rotation A can have a
generally similar configuration to the portion depicted above the
axis A, with the understanding that embodiments of clutches often
have certain conventional features that are not completely
symmetrical about the axis of rotation A. In the illustrated
embodiment, the clutch 20 includes a journal bracket (or mounting
shaft) 22, a pulley (or sheave) 24, a rotor assembly 26, a housing
assembly 28, a valve assembly 30, an electromagnetic coil assembly
32, first bearing sets 34, second bearing sets 36, a reservoir 38,
a working chamber 40, a seal bearing 42, and a sensor assembly 44.
The clutch 20 defines an axis of rotation A.
The journal bracket (or mounting shaft) 22 can be a stationary
(i.e., non-rotating) component that is secured to a desired
mounting location, such as an engine block in a vehicle's engine
compartment. It should be understood that while described as being
"stationary" the journal bracket 22 can be installed within a
moving vehicle, and the term "stationary" is used herein in
relation to the mounting location. In the illustrated embodiment,
the journal bracket 22 includes an axially extending shaft portion
22-1 and a generally radially extending flange portion 22-2. A
conduit 22-3 can optionally be defined through the journal bracket
22, and can extend along substantially an entire axial length of
the shaft portion 22-1. As illustrated, the conduit 22-3 is
coaxially aligned with the axis A. Electrical wires or other items
can pass through the conduit 22-3, as desired for particular
applications. Suitable methods of manufacturing the journal bracket
22 include casting it from metallic material such as iron or steel.
In a preferred embodiment, the journal bracket 22 is cast from
ductile iron and then machined.
The housing assembly 28 of the illustrated embodiment includes a
base 28-1 and a cover 28-2. The base 28-1 and the cover 28-2 can be
secured together with any suitable means, such as using fasteners,
welding, or the like. Cooling fins 28-3 can be provided on an
exterior of the housing assembly 28 to help dissipate heat
generated by the clutch 20 to ambient air. As shown in the
embodiment of FIG. 1, a plurality of generally radially-extending,
angularly-spaced cooling fins 28-3 are positioned on a front face
of the cover 28-2. Additional generally radially-extending,
circumferentially-spaced cooling fins 28-4 are located on an outer
face of the base 28-1 of the housing assembly 28. It should be
appreciated that the particular number, arrangement and
configuration of the cooling fins 28-3 and/or 28-4 can vary as
desired for particular applications. For instance, additional
cooling fins can be placed on the base 28-1, the cover 28-2 and/or
other components of the clutch 20 in further embodiments. Providing
the cooling fins 28-3 and/or 28-4 on the housing assembly 28, when
configured as a rotational input for the clutch 20, allows the
cooling fins 28-3 and/or 28-4 to rotate whenever there is a
rotational input to the clutch 20, thereby facilitating heat
dissipation. In the illustrated embodiment, the housing assembly 28
is rotatably supported on the shaft portion 22-1 of the journal
bracket 22 by the first bearing sets 34, and the housing assembly
28 generally encircles the shaft portion 22-1. In particular, the
first bearing sets 34 can support the base 28-1, at a location
generally axially aligned with the pulley 24 and radially inward
from the reservoir 38, though other configurations are possible in
further embodiments. The first bearing sets 34 can include tapered
roller bearings, which can provide relatively high load capacity,
or other types of bearings as desired. The cover 28-2 of the
housing assembly 28 can further be rotationally supported on the
rotor assembly 26 by the bearing seal 42. The bearing seal 42 can
provide both a fluidic sealing function and a structural rotational
support function, such as in the form of a journal bearing. As
shown in FIG. 1, the first set of bearings 34 and the bearing seal
42 are located on opposite sides of the working chamber 40,
measured in the axial direction. The base 28-1 and the cover 28-2
of the housing assembly 28 can each be cast from metallic material,
such as die cast aluminum, and then machined. Significantly, the
housing assembly 28 can form part of an input or torque-accepting
portion of the clutch 20, as explained further below.
In the illustrated embodiment, the housing assembly 28 carries the
reservoir 38, which rotates with the housing assembly 28. The
reservoir 38 can hold a supply of a shear fluid (e.g., silicone
oil) for use by the clutch 20, with a majority of the shear fluid
held in the reservoir 38 when the clutch 20 is disengaged. Because
the housing assembly 28 is part of an input subassembly, the
housing assembly 28 always rotates whenever there is a rotational
input to the housing assembly 28. Rotation of the housing assembly
28 in turn keeps the shear fluid under pressure while in the
reservoir 38, allowing the shear fluid to be maintained at a
relatively high level of kinetic energy to help facilitate quick
engagement of the clutch 20. In one embodiment, the reservoir 38
can be provided as a generally annular cavity in the base 28-1 of
the housing assembly 28. A reservoir cover 46 can be provided to
define part of a boundary of the reservoir 38. In the illustrated
embodiment, the reservoir cover 46 is configured as a generally
annular plate attached to the base 28-1, such as by a press fit,
swaging, the use of fasteners, or the like. One or more outlet
bores (also called reservoir bores) 46-1 can be provided in the
reservoir cover 46 (or alternatively, on another boundary portion
of the reservoir 38) to allow shear fluid out of the reservoir 38,
and can be controlled by the valve assembly 30. The location of the
reservoir 38 in the housing assembly 28 allows the shear fluid to
remain relatively close to the cooling fins 28-3 and/or 28-4 and
ambient air, to facilitate heat dissipation.
The pulley (or sheave) 24 can be fixedly secured directly or
indirectly to the housing assembly 28, such as to the base 28-1,
and is configured to accept rotational input from a belt (not
shown). The housing assembly 28 can co-rotate with the pulley 24.
In the illustrated embodiment, the pulley 24 is axially positioned
forward of the flange portion 22-2 of the journal bracket 22.
Moreover, in the illustrated embodiment, the pulley 24 is
configured as a separate element that is attached, using suitable
fasteners, to the housing assembly 28. However, in further
embodiments the pulley 24 could be integrally and monolithically
incorporated into a portion of the housing assembly 28. A size
(i.e., diameter) of a belt engagement portion of the pulley 24 can
be selected to help provide a desired rotational input speed to the
clutch 20, as will be understood by persons of ordinary skill in
the art. In the illustrated embodiment, the pulley 24 provides a
relatively large belt engagement diameter, thereby allowing
relatively high input speeds, which in turn facilitates relatively
high output speeds when the clutch 20 is engaged. Attaching the
pulley 24 to the housing assembly 28 can allow a "hollow" center
section of the pulley 24, because the pulley 24 need not extend
inward beyond a generally radially outward portion of the housing
assembly 28, thereby helping to reduce overall mass of the clutch
20. In one embodiment, the pulley 24 can be cast from a metallic
material such as iron or steel, and then machined. In an
alternative embodiment, the pulley 24 can be spun formed and
attached to a separate hub section (not shown) made from a casting.
In yet another alternative embodiment, a roll forming or circular
forming process in combination with welding or brazing as described
in U.S. Pat. No. 4,080,704 can be used. Any suitable further
manufacturing process or processes can be used to make the pulley
24.
The rotor assembly 26 of the illustrated embodiment includes a disk
26-1, a bearing hub 26-2, and a flow guide 26-3. The disk 26-1 and
the bearing hub 26-2 of the rotor assembly 26 can be configured as
separate components fixedly secured together with a suitable
connection, such as a press-fit, knurled, threaded, splined, or
other connection, such that those components rotate together (i.e.,
co-rotate). In alternative embodiments, the disk 26-1 and the
bearing hub 26-2 can be integrally and monolithically formed
together. The rotor assembly 26 can be rotatably supported on the
shaft portion 22-1 of the journal bracket 22 by the second bearing
sets 36. The second bearing sets 36 can include tapered roller
bearings, which can provide relatively high load capacity, or other
types of bearings as desired. As shown in FIG. 1, the rotor
assembly 26 is positioned to generally encircle the shaft portion
22-1 of the journal bracket 22. Components of the rotor assembly 26
can each be formed by casting, and the ribs, openings, etc. can be
formed by machining.
The disk 26-1 of the rotor assembly 26 can include a number of
concentric annular ribs on both front and rear sides near an outer
diameter portion in a conventional arrangement. Those annular ribs
can complement similar ribs on the cover assembly 28 along the
working chamber 40. In the illustrated embodiment, the disk 26-1 is
enclosed by the housing assembly 28. One or more fluid openings
(not shown) can be formed generally axially through the disk 26-1,
such as near an outer diameter portion, in a conventional manner in
order to permit shear fluid in the working chamber 40 to pass
between front and rear sides of the disk 26-1. A return bore
including a first return bore portion 26-1B and a second return
bore portion 26-1B' can be provided through the disk 26-1. In the
embodiment shown in FIGS. 1 and 2, the first return bore portion
26-1B extends generally radially through the entire disk 26-1
(including through an outer diameter portion of the disk 26-1), and
the second return bore portion 26-1B' extends generally axially
from a rear face of the disk 26-1 to the first return bore portion
26-1B. The flow guide 26-3 can be a sleeve-like member attached to
the disk 26-1, or other suitable mounting location. In the
illustrated embodiment, the flow guide 26-3 is attached to the disk
26-1 and provides an interior passageway that connects in fluid
communication with the second return bore portion 26-1B' as well as
with the reservoir 38. The flow guide 26-3 can traverse the
reservoir cover 46, such as by passing through a central opening
46-2 in the reservoir cover 46.
In the illustrated embodiment of the rotor assembly 26, the bearing
hub (also called a fan hub) 26-2 includes a generally
axially-extending sleeve portion 26-2A, a generally
radially-extending flange portion 26-2B, and a pilot portion 26-2C.
The sleeve portion 26-2A can have a generally cylindrical shape,
and can be generally axially aligned with both the disk 26-1 and
the second bearing sets 36. The seal bearing 42 can be engaged
between the bearing hub 26-2 (and specifically the sleeve portion
26-2A) and the cover 28-2 of the housing assembly 28. The seal
bearing 42 can also adjoin the disk 26-1, and can be aligned or
closely positioned in the axial direction relative to the second
bearing sets 36. The flange portion 26-2B can be positioned at or
near a forward end of the sleeve portion 26-2A, and the pilot
portion 26-2C can be positioned at a central, forward-facing
portion of the flange portion 26-2B. The flange portion 26-2B and
the pilot portion 26-2C can each at least partially extend beyond
(or outside of) the housing assembly 28, such that the flange
portion 26-2B, the pilot portion 26-2C and/or other portions of the
bearing hub 26-2 of the rotor assembly 26 can provide a mounting
surface for an output structure (e.g., fan, pump, shaft, etc.) at
or near a front of the clutch 20. It should be noted, however, that
in alternative embodiments the output structure could be mounted
elsewhere. In this way, the rotor assembly 26 can form part of a
selectively controllable output or torque-delivering portion of the
clutch 20, as explained further below. Use of the bearing hub 26-2
allows attachment geometry for an output member (e.g., fan, etc.)
to be relatively easily adjusted without a need to re-design other
components of the clutch 20. For instance, the same basic overall
clutch design could be provided with a variety of different bearing
hub 26-2 configurations to suit different applications.
The working chamber 40 (synonymously called a working area) is
defined between the rotor assembly 26 and the housing assembly 28.
In the illustrated embodiment the working chamber 40 extends along
opposite front and rear sides of the disk 26-1, though in further
embodiments the working chamber 40 could be limited to primarily
one side of the disk 26-1. The presence of the shear fluid in the
working chamber 40 creates a fluid friction coupling between the
rotor assembly 26 and the housing assembly 28 to engage the clutch
20 and transmit torque between input and output components. An
instantaneous percentage of torque transmission can vary as a
function of the amount of shear fluid in the working chamber 40.
Generally, the shear fluid is delivered to the working chamber 40
from the reservoir 38 along a fluid delivery path 48, and is
returned to the reservoir 38 from the working chamber 40 through
the return path 50. The fluid delivery and return paths 48 and 50
are each represented schematically by arrows in FIGS. 1 and 2. As
shown in FIGS. 1 and 2, the fluid delivery path 48 extends from the
reservoir 38 through the outlet bore 46-1 in the reservoir cover 46
to the working chamber 40. In the illustrated embodiment, the
return path 50 extends substantially radially from a portion of the
working chamber 40 directly radially outward from the disk 26-1 of
the rotor assembly 26 through the first return bore portion 26-1B
in the disk 26-1, then turns and passes through the second return
bore portion 26-1B' and the flow guide 26-3 before being returned
to the reservoir 38. In that way, the shear fluid can pass (or be
pumped) directly radially inward from the working chamber 40 along
the fluid return path 50 through the first return bore portion
26-1B. Persons of ordinary skill in the art will appreciate that
the precise location and shape of the fluid .[.deliver.].
.Iadd.delivery .Iaddend.and return paths 48 and 50 can each vary as
desired for particular applications. One or more suitable pumping
structures can be included at or along the working chamber 40 to
dynamically pump the shear fluid out of the working chamber 40
through the return path 50. Further discussion of one embodiment of
a pumping structure is provided below with respect to the
discussion of FIG. 3.
The valve assembly 30 can be attached to and carried by the housing
assembly 28. In general, the valve assembly 30 is used to
selectively cover and uncover the opening outlet bore 46-1 from the
reservoir 38. When the outlet bore 46-1 is uncovered (i.e.,
opened), the shear fluid is allowed to flow from the reservoir 38
to the working chamber 40 along the fluid delivery path 48. The
valve assembly 30 can be biased to an open position by default, for
instance using a spring bias force. As explained further below,
energizing the electromagnetic coil assembly 32 can actuate the
valve assembly 30 to at least partially cover the outlet bore 46-1.
Further discussion of suitable configurations of the valve assembly
30 is provided below with respect to the discussion of FIG. .[.4.].
.Iadd.6.Iaddend..
The electromagnetic coil assembly 32 as shown in FIG. 1 can include
one or more wound coils of high temperature insulated copper wire
placed in a cup (e.g., a steel cup) used to direct the flux for
actuation of the valve assembly 30. In one embodiment, as discussed
further below with respect to FIG. 6, the electromagnetic coil
assembly 32 can have multiple windings. The coil .[.42.]. .Iadd.of
the coil assembly 32 .Iaddend.can be rotationally fixed relative to
the journal bracket 22, and can be positioned adjacent to the
housing assembly 28 and the valve assembly 30. In the illustrated
embodiment, the coil .[.22.]. .Iadd.of the coil assembly 32
.Iaddend.encircles and is supported by the shaft portion 22-1 of
the journal bracket 22. In the illustrated embodiment, the coil
assembly 32 is positioned generally rearward of the housing
assembly 28 and the pulley 24, though the electromagnetic coil
assembly 32 can be placed in other locations in alternative
embodiments.
A variety of alternative control schemes are possible for operating
the clutch 20. In one embodiment, the electro-magnetic coil
assembly 32 can be energized in a coarse on/off manner such that
the valve assembly 30 tends to remain in either a fully open
position (the default position) or a fully closed position when the
coil assembly 32 is selectively energized. In another embodiment,
the coil assembly 32 can be energized using pulse width modulated
(PWM) signals from an electronic engine controller (not shown). PWM
signals allow a dynamically variable average volume of shear fluid
to flow out of the reservoir 38. Depending on the pulse width
(i.e., duration) and frequency of PWM signals, the valve assembly
30 can variably adjust the amount of shear fluid allowed to pass
out of the reservoir 38 through the outlet bore 46-1 to the working
chamber 40 over time. That is, the PWM signals cause the coil
assembly 32 to open and close the valve assembly 30, and an average
amount of time that the valve assembly 30 is open (i.e., uncovering
the outlet bore 46-1) dictates the average amount of shear fluid
that flows out of the reservoir 38. Greater pulse widths and/or
greater frequencies of PWM signals will tend to close the valve
assembly 30 more, on average, allowing lower average volumes of
shear fluid to pass to the working chamber 40. This PWM control
scheme permits the clutch 20 to be operated at selectively variable
speeds, such that the rotor assembly 26 can rotate at anywhere from
0% to approximately 100% of the rotational speed of the housing
assembly 28 and the pulley 24, rather than merely in a coarse and
binary on/off fashion.
The speed sensor assembly 44 can include a target wheel carried by
and rotating with the bearing hub 26-2 of the rotor assembly 26
that is located in close proximity to a Hall Effect sensor carried
by the journal bracket 22. The Hall Effect sensor can detect each
revolution of the target wheel in order to determine an output
speed of the clutch 20, which can be used to adjust control of the
valve assembly 30 and/or for other purposes. In the illustrated
embodiment, the sensor assembly 44 can be located, in the axial
direction, within the pilot portion 26-2C of the bearing hub 26-2
of the rotor assembly 26. It should be noted that in further
embodiments, other types of sensors can be used, or the sensor
assembly can be omitted entirely.
FIG. 3 is a cross-sectional view of an interchangeable pump bore
insert 60 suitable for use with the clutch 20. The pump bore insert
60 can function as part of a pump assembly, to facilitate pumping
the shear fluid from the working chamber 40 to the reservoir 38
along the fluid return path 50. In the illustrated embodiment, the
pump bore insert 60 includes a shank 60-1, a head 60-2, an
engagement structure 60-3, and a bore 60-4. The shank 60-1 can be
threaded, and can be engaged with a cooperating threaded region of
a radially outer end of the first return bore portion 26-1B, such
that the shank 60-1 can extend at least partially into the first
return bore portion 26-1B. The head 60-2 can adjoin the shank 60-1,
and the engagement structure 60-3 is supported by the head 60-2 and
in various embodiments can be located on, in or along the head
60-2. The engagement structure 60-3 can be, for example, an
engagement for a flat or Phillips-head screwdriver or an engagement
for an Allen, Reynolds, Torx.RTM. or other tool bit, generally
located in a central, outwardly-facing portion of the head 60-2. In
alternative embodiments, the engagement structure 60-3 can comprise
flats on outer surfaces of the head 60-2. In still further
embodiments, the engagement structure 60-3 can be located in, on or
along the shank 60-1. The bore 60-4 can extend between opposite
ends of the pump bore insert 60, such as through both the shank
60-1 and the head 60-2. The bore 60-4 can be configured as a
generally cylindrical passageway, or can have another suitable
configuration that allows for fluid flow therethrough. The bore
60-4 can be in fluid communication with the first portion of the
first return bore portion 26-1B and the fluid return path 50. In
that way, the shear fluid can pass (or be pumped) directly radially
inward from the working chamber 40 through the bore 60-4 and
through the first return bore portion 26-1B along the fluid return
path 50.
The pump bore insert 60 can be configured to resemble a bolt
modified to include the bore 60-4. Indeed, it is possible to make
the pump bore insert 60 by machining (e.g., drilling) the bore 60-4
through a conventional bolt of a suitable configuration. In
alternative embodiments, the pump bore insert 60 can have a
different configuration. For instance, the head 60-2 can be a
separate element, such as a conformable seal strip, block, etc.,
that is attached to the shank 60-1. As shown in FIG. 3, the pump
bore insert 60 has a dimension (e.g., diameter) D.sub.1, and the
bore 60-4 has a dimension (e.g., diameter) D.sub.2.
The pump bore insert 60 can be arranged relative to an immediately
surrounding structure 62. In one embodiment, the pump bore insert
60 is engaged at an outer diameter portion of the disk 26-1, such
that the immediately surrounding structure 62 can be an outer
diameter surface of the disk 26-1 (see FIG. 2). A countersunk
portion 62-1 can be provided in or along the surrounding structure
62 to countersink the pump bore insert 60 relative to the working
chamber 40, which can help prevent the pump bore insert 60 from
protruding into the working chamber 40 if desired.
As best shown in FIGS. 1 and 2, an access opening 64 can be
provided in the housing assembly 28, such as in the base 28-1,
which permits access to the interchangeable pump bore .Iadd.insert
.Iaddend.60 while the cover 28-2 is installed. The access opening
64 can have a dimension D.sub.3 that is larger than the dimension
D.sub.1 of the interchangeable pump bore insert .[.60-2.].
.Iadd.60.Iaddend., to help ensure sufficient room for a suitable
tool to pass through the housing assembly 28 to engage, remove and
replace the interchangeable pump bore insert 60, as desired. A plug
66, such as a threaded bolt or other suitable element, can be
removably engaged with the access opening 64 to close and seal the
housing assembly 28 and help prevent leakage of the shear
fluid.
The dimension D.sub.2 of the bore 60-4 can be selected as desired
for particular applications. Larger dimensions for D.sub.2
generally allow for greater pumping rates, while smaller dimensions
for D.sub.2 can generally allow lower pumping rates. In this way
the bore 60-4 provides a pump metering function. The dimension
D.sub.2 of the bore 60-4 can be varied in size by replacing the
interchangeable pump bore insert 60 with a different insert 60
having a different configuration.
Persons of ordinary skill in the art will recognize that the
interchangeable pump bore insert 60 allows a dimension D.sub.2 of
the pump bore 60-4 to be easily changed. By adjusting a parameter
such as the dimension D.sub.2, changes to operational
characteristics of the clutch 20 (e.g., shear fluid pressurization
for pumping along the fluid return path 50) can be tuned to operate
with a variety of output devices (e.g., fans) without requiring
complete redesign or disassembly of the entire clutch 20. Further
explanation of the method of adjusting the clutch 20 is provided
below. It should also be understood that the interchangeable pump
bore insert 60 can be utilized with nearly any type of viscous
clutch, including those configured differently than the clutch 20.
For instance, the interchangeable pump bore .Iadd.insert
.Iaddend.60 can be utilized in a clutch that provides a fluid
return path through a housing assembly rather than through a rotor
assembly as with the clutch 20. The configuration shown in FIGS.
1-3 is provided merely by way of example and not limitation.
FIG. 4 is a cross-sectional view of another portion of the clutch
20, taken along line 4-4 of FIG. 1, and FIG. 5 is a perspective
view of an embodiment of a wiper 63 for the clutch 20. The wiper 63
can be positioned in, at or along the working chamber 40 of the
clutch 20, and can act as a dam to help pump the working fluid out
of the working chamber 40 and through the fluid return path 50. The
wiper 63 can be used in conjunction with other pumping structures
(not shown), such as one or more additional pump, dam or baffle
elements positioned radially or axially opposite the wiper 63 along
the working chamber 40. In the illustrated embodiment, the wiper 63
is attached to the disk 26-1 of the rotor assembly 26, such as
using suitable fasteners. Moreover, as shown in FIG. 4, the wiper
63 is attached to the surrounding structure 62 at the outer
diameter of the disk 26-1 of the rotor assembly 26, and adjacent to
the pump bore insert 60 and the first return bore portion 26-1B. In
an .[.alternatively.]. .Iadd.alternative .Iaddend.embodiment, the
wiper 63 could be attached to an inner diameter portion of the
housing assembly 28. The wiper 63 can protrude into the working
chamber 40 relative to immediately surrounding structure 62, which
facilitates pressurization of the working fluid to pump the shear
fluid along the fluid return path 50. An amount of protrusion of
the wiper .[.60.]. .Iadd.63 .Iaddend.into the working chamber 40
can influence a degree of pumping of the shear fluid through the
fluid return path 50, with greater dimensions for the length L
generally providing increased pumping pressures for increased
pumping rates, as well as influencing an off speed of the clutch
20.
As shown most clearly in FIG. 5, the wiper 63 can have a generally
rectangular perimeter and be curved to .[.corresponding.].
.Iadd.correspond .Iaddend.to a mounting location (e.g., the
surrounding structure 62 on the disk 26-1). The wiper 63 can define
an arc length L, which can be established in relation to a central
angle (measured from the axis A). In one embodiment, the arc length
L can be defined by a central angle of approximately 15.degree.. A
thickness of the wiper can be selected to provide a desired amount
of protrusion into the working chamber 40. The arc length L and/or
the thickness of the wiper 63 can be increased or decreased by
selecting an appropriate configuration of the wiper 63. Because the
wiper 63 can be a separate element, it can easily be modified
without requiring a major re-design of the clutch 20, such as a new
casting for the disk 26-1. It should also be understood that the
wiper 63 can be utilized with nearly any type of viscous clutch,
including those configured differently than the clutch 20. For
instance, the wiper 63 can be utilized in a clutch that provides a
fluid return path through a housing assembly rather than through a
rotor assembly as with the clutch 20. The configuration shown in
FIGS. 4 and 5 is provided merely by way of example and not
limitation.
FIG. 6 is a cross-sectional view of an embodiment of a valve
assembly suitable for use with the clutch 20. The valve assembly 30
of the illustrated embodiment includes a translating armature 70, a
field armature (also called a field rotor) 72, a bias spring 74, a
diaphragm 76, a rod 78, a control member 80, a bellows 82, and a
valve element 84. It should be noted that the cross-sectional view
of the valve assembly 30 .[.it.]. .Iadd.is .Iaddend.taken at a
sectional plane with a different angular orientation than the
sectional plane of FIGS. 1 and 2, which means that not all
structures or portions of structures are visible in each view.
In one embodiment, the field armature 72 can be fixed (i.e.,
non-translating) at a location proximate the electromagnetic coil
assembly 32 and the translating armature 70 can be positioned at
least partially inside the field armature 72. The bias spring 74
can bias the translating armature 70 relative to the field armature
72 to a default position, such as rearward against the field
armature 72. The rod 78 can be engaged with or secured to the
translating armature 70 and can pass through an opening 28-1B in
the base 28-1 of the housing assembly 28, with the diaphragm 76
providing fluidic sealing at the opening 28-1B. The control member
80 can be configured as a bolt and can be engaged to the rod 78
generally opposite the translating armature 70. The control member
80 can pass through an opening 46-3 in the reservoir cover 46, and
the bellows 82 can provide fluidic sealing at the opening 46-3. The
valve element 84 can be attached to the control member 80 generally
opposite the rod 78, and can provide a seating surface (not visible
in FIG. .[.4.]. .Iadd.6.Iaddend.) for selectively covering the
outlet bore 46-1 (see FIGS. 1 and 2).
Energizing the coil assembly 32 generates magnetic flux that can
pass through the field armature 72 and can cause the translating
armature 70 to translate, which in turn translates the rod 78, the
control member 80 and the valve element 84. Energizing the coil
.Iadd.assembly .Iaddend.32 creates a magnetic force that generally
works against a spring force of the bias spring 74. The selective
energization of the coil assembly 32 thus allows the translating
armature 70, as well as connected structures such as the valve
element 84, to move back and forth axially in a linear fashion
rather than teetering/pivoting at an angle like most viscous clutch
valves. The linear translation action allows the clutch 20 to open
and close two or more valve assemblies (only one is visible in FIG.
.[.4.]. .Iadd.6.Iaddend.) concurrently.
In an alternative embodiment, the valve assembly 30 can be
configured similarly to that described in U.S. Pat. No. 6,419,064,
entitled "Fluid Friction Coupling." It should be understood that
nearly any known type of electromagnetically actuated valve
assembly can be utilized in alternative embodiments.
FIG. 7 is a schematic block diagram of an embodiment of the valve
assembly 30 that includes a translating armature 70, a field
armature 72, a bias spring 74, and a plurality of valve
subassemblies 30-1 to 30-n. The translating armature 70, the field
armature 72, and the bias spring 74 can be configured in any
desired manner, such as in the manner described above with respect
to FIG. 6. In one embodiment, each of the valve subassemblies 30-1
to 30-n can include a rod 78, control bolt 80 and valve element 84
(e.g., as described above with respect to FIG. .[.4.].
.Iadd.6.Iaddend.), and each of the valve subassemblies 30-1 to 30-n
can be engaged with or attached to the translating armature 70
(e.g., at different angular positions about the axis of rotation A)
for common (e.g., concurrent) actuation. For a relatively large
clutch (e.g., providing approximately 2000 Nm or more of torque),
extra oil flow is needed beyond that provided with a typical single
valve and the present inventors have discovered that the use of two
or more of the valve subassemblies 30-1 to 30-n will solve that oil
flow problem. Each valve member 84 moved by the translating
armature 70 can cover and uncover a different outlet bore 46-1.
FIG. 8 is a schematic block diagram of an embodiment of the
electromagnetic coil assembly 32 suitable for use with the clutch
20 and the valve assembly 30. In the illustrated embodiment, the
electromagnetic coil assembly 32 includes two windings 32-1 and
32-2, each having terminals 32-3. The multiple windings 32-1 and
32-2 allow the clutch 20 to be used at different voltage levels
(e.g., 12V or 24V) depending on how the windings 32-1 or 32-2 are
connected to an operational power source (not shown) through the
associated terminals 32-3. For example, the windings 32-1 or 32-2
can be wired in series for use in a 24 volt or parallel for use in
a 12 volt application. Persons of ordinary skill in the art will
recognize that any desired number of windings can be provided in
further embodiments, and only a single winding or more than two
windings can be provided in such further embodiments.
FIG. 9 is a flow chart of an embodiment of a method of assembling
and using a clutch 20. The method can begin by initially
fabricating and assembling the clutch (step 100). Initial operation
of the clutch 20 can include setting an initial configuration of an
interchangeable pump bore insert 60 for a pump assembly. The
initial configuration can include first settings for a dimension
D.sub.2 of a bore 60-4 and/or a length L of a wiper 63, and/or
other configuration parameters. The fully assembled clutch 20 can
then optionally be operated, that is to say the clutch 20 can be
used to selectively transmit torque from an input to an output
(step 102). In conjunction with operating the clutch at step 102, a
shear fluid can be pumped along a fluid return path 50 that passes
radially through a disk 26-1 of a rotor assembly 26 (step 104). The
interchangeable pump bore insert 60 can be used to help pump the
shear fluid from the working chamber 40 to the reservoir 38 along
the fluid return path 50. The first settings can cause the shear
fluid to be pumped from the working chamber 40 at a first rate at
step 104. Next, the configuration of the clutch 20 can be adjusted
(step 106). Adjustment can include replacement of the
interchangeable pump bore insert 60, such as to provide second
settings for a dimension D.sub.2 of the bore 60-4 and/or a length L
of the wiper 63, and/or other configuration parameters. In order to
effectuate a desired adjustment or component interchange, a tool
can be inserted through the access opening 64 in the housing
assembly 28 to engage the engagement structure 60-3 of the
interchangeable pump bore insert 60, for instance. Adjustment
and/or interchange could be provided as part of regular
maintenance, a remanufacturing operation, as part of reassignment
for a different application (e.g., to use the clutch 20 with a
different output fan, in a different vehicle, etc.), or for any
other desired reason. The clutch 20 can then be operated, that is
to say the clutch 20 can again be used to selectively transmit
torque from an input to an output (step 108). In conjunction with
operating the clutch at step 108, the shear fluid can again be
pumped along the fluid return path 50 that passes radially through
the disk 26-1 of the rotor assembly 26 (step 110). The second
settings can cause the shear fluid to be pumped from the working
chamber 40 at a second rate at step 110, and the second rate can be
different from the first rate. This allows a diameter of the bore
60-4 to be changed, for instance, to provide different metering of
shear fluid being pumped back to the reservoir 38.
Persons of ordinary skill in the art will recognize that various
steps described with respect to FIG. 9 can be omitted in
alternative embodiments, and various additional steps not
specifically mentioned can be performed in conjunction with the
enumerated steps. For instance, although the method illustrated in
FIG. 9 indicates that a clutch is operated prior to adjustment, it
is possible to adjust the clutch without undergoing actual use in
the field, such as by making adjustments on a factory floor or in a
test laboratory to provide enhanced quality control prior to
completion of an initial fabrication process.
DISCUSSION OF POSSIBLE EMBODIMENTS
The following are non-exclusive descriptions of possible
embodiments of the present invention.
A viscous clutch can include a housing assembly; a rotor assembly;
a reservoir to hold a supply of a shear fluid; a working chamber
operatively positioned between the housing assembly and the rotor
assembly, wherein selective introduction of the shear fluid to the
working chamber facilitates selective torque transmission between
the housing assembly and the rotor assembly; and a fluid return
bore that extends radially through at least an outer diameter
portion of the rotor assembly to the working chamber, the fluid
return bore forming at least a portion of a fluid return path from
the working chamber to the reservoir.
The viscous clutch of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following features, configurations and/or additional
components:
an electromagnetically actuated valve assembly configured to
controllably translate a first valve element that controls flow of
the shear fluid between the reservoir and the working chamber;
a second valve element configured to be actuated concurrently with
the first valve element to further control flow of the shear fluid
between the reservoir and the working chamber;
an electromagnetic coil assembly positioned adjacent to the housing
assembly, wherein the electromagnetic coil assembly includes first
and second windings each having terminals electrically connectable
in series or parallel for operation at different voltages;
the rotor assembly can include a disk, wherein the fluid return
bore extends radially through at least a portion of the disk; and a
bearing hub connected to the disk for co-rotation therewith,
wherein the bearing hub extends beyond the housing assembly to
provide a mounting location for an output member;
a pulley connected to the housing assembly for co-rotation with the
housing assembly;
a rotationally fixed journal bracket having a shaft portion; a
first set of tapered roller bearings for rotationally supporting
the housing assembly on the shaft portion of the journal bracket;
and a second set of tapered roller bearings for rotationally
supporting the rotor assembly on the shaft portion of the journal
bracket;
the housing assembly can include a plurality of cooling fins, and
the cooling fins can be configured to rotate whenever there is a
rotational input to the viscous clutch;
an interchangeable pump bore insert positioned at least partially
within the fluid return bore, wherein the interchangeable pump bore
insert includes a bore in fluid communication with the fluid return
bore;
an access opening in the housing assembly configured to allow
access to the interchangeable pump bore insert; the interchangeable
pump bore .Iadd.insert .Iaddend.can be engaged at an outer diameter
portion of the rotor assembly;
a wiper at an outer diameter portion of the rotor assembly and
protruding, at least partially, into the working chamber;
the wiper can be removably attached to a disk of the rotor
assembly; and/or
a reservoir cover defining a portion of a boundary of the
reservoir; and a flow guide that traverses the reservoir cover to
deliver the shear fluid from fluid return bore of the rotor
assembly to the reservoir along the fluid return path.
A method for selective torque transmission can include delivering a
rotational input to a housing assembly; selectively delivering a
shear fluid to a working chamber; transmitting torque to a rotor
assembly as a function of volume of the shear fluid selectively
delivered to the working chamber; and returning the shear fluid
from the working chamber to a reservoir along a substantially
radial bore through a disk of the rotor assembly.
The method of the preceding paragraph can optionally include,
additionally and/or alternatively, any one or more of the following
steps, features, and/or configurations:
providing a first interchangeable pump bore insert to provide
pumping at a first rate when returning the shear fluid from the
working chamber to the reservoir;
replacing the first interchangeable pump bore insert having a bore
of a first size with a second interchangeable pump bore insert
having a bore of a second size that is different from the first
size; and/or
securing a wiper to an outer diameter portion of the disk adjacent
to the substantially radial bore such that the wiper protrudes into
the working chamber.
A viscous clutch can include a housing assembly; a rotor assembly;
a reservoir to hold a supply of a shear fluid; a working chamber
operatively positioned between the housing assembly and the rotor
assembly, wherein selective introduction of the shear fluid to the
working chamber facilitates selective torque transmission between
the housing assembly and the rotor assembly; and a pump bore insert
having a bore in fluid communication with a fluid return path
extending from the working chamber to the reservoir.
The viscous clutch of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following features, configurations and/or additional
components:
the pump bore insert can be removably engaged with the rotor
assembly;
the pump bore insert can include a threaded shank, a head adjoining
the shank, and an engagement structure located on or along at least
one of the shank and the head, the bore can extend through the
shank and the head;
a wiper engaged at an outer diameter portion of the rotor assembly
adjacent to the pump bore insert and extending radially outward
from a surrounding surface of the rotor assembly;
the wiper can have a generally rectangular perimeter and be
curved;
a fluid return bore that extends radially through at least a
portion of the rotor assembly to the working chamber, the fluid
return bore forming at least a portion of the fluid return path
from the working chamber to the reservoir;
a reservoir cover defining a portion of a boundary of the
reservoir; and a flow guide that traverses the reservoir cover to
deliver the shear fluid from fluid return bore of the rotor
assembly to the reservoir along the fluid return path;
an electromagnetically actuated valve assembly configured to
controllably translate a first valve subassembly that controls flow
of the shear fluid between the reservoir and the working
chamber;
a second valve subassembly configured to be actuated concurrently
with the first valve subassembly to further control flow of the
shear fluid between the reservoir and the working chamber;
an electromagnetic coil assembly positioned adjacent to the housing
assembly, wherein the electromagnetic coil assembly includes first
and second windings with separate terminals;
the rotor assembly can include a disk, wherein the fluid return
bore extends radially through at least a portion of the disk, and
wherein the pump bore insert is positioned at least partially
within the fluid return bore;
the rotor assembly can include a bearing hub connected to the disk
for co-rotation therewith, wherein the bearing hub extends beyond
the housing assembly to provide a mounting location for an output
member;
a pulley connected to the housing assembly for co-rotation with the
housing assembly;
a rotationally fixed journal bracket having a shaft portion; a
first set of tapered roller bearings for rotationally supporting
the housing assembly on the shaft portion of the journal bracket;
and a second set of tapered roller bearings for rotationally
supporting the rotor assembly on the shaft portion of the journal
bracket;
an access opening in the housing assembly configured to allow
access to the pump bore insert;
the housing assembly can include a base supported by bearings; and
a cover attached to the base, wherein the access opening extends
through a portion of the base;
the pump bore insert can be removable through the access opening
while the cover is attached to the base; and/or
a plug removably engaged with the access opening.
Further, a kit for use with the viscous clutch described above can
include a replacement pump bore insert of a different
configuration, such as having a bore of a different size.
A method for using a viscous clutch can include engaging a first
pump bore insert along a working chamber of the viscous clutch at a
fluid return bore; and replacing the first pump bore insert with a
second pump bore insert of a different configuration.
The method of the preceding paragraph can optionally include,
additionally and/or alternatively, any one or more of the following
steps, features, and/or configurations:
the first and second pump bore inserts can each, respectively, be
positioned at least partially within a radially extending portion
of a fluid return bore along a fluid return path;
inserting a tool through an access opening in a housing assembly of
the viscous clutch; and engaging the tool with the first pump bore
insert;
removing the first pump bore insert from the viscous clutch;
the replacement second pump bore insert can provide different
pumping characteristics to the viscous clutch than the removed
first pump bore insert; and/or
positioning a removable wiper to protrude radially into the working
chamber, wherein the removable wiper is positioned adjacent to the
pump bore insert.
A method for use with a viscous clutch can include positioning a
first pump bore insert along a working chamber of the viscous
clutch and at least partially within a fluid return bore; removing
the first pump bore insert from the viscous clutch; and positioning
a second pump bore insert along the working chamber of the viscous
clutch and at least partially within the fluid return bore in place
of the first pump bore insert.
The method of the preceding paragraph can optionally include,
additionally and/or alternatively, any one or more of the following
steps, features, and/or configurations:
positioning a removable wiper to protrude into the working chamber,
wherein the removable wiper is positioned adjacent to the pump bore
insert; and removing the removable wiper from the viscous
clutch;
the second pump bore insert can have a differently sized bore than
the first pump bore insert; and/or
metering shear fluid flow with the first or second pump bore
insert.
A method for a viscous clutch can include pumping shear fluid
through a bore having a first diameter; and reconfiguring the bore
to have a second diameter different from the first diameter.
SUMMATION
Any relative terms or terms of degree used herein, such as
"substantially", "essentially", "generally" and the like, should be
interpreted in accordance with and subject to any applicable
definitions or limits expressly stated herein. In all instances,
any relative terms or terms of degree used herein should be
interpreted to broadly encompass any relevant disclosed embodiments
as well as such ranges or variations as would be understood by a
person of ordinary skill in the art in view of the entirety of the
present disclosure, such as to encompass ordinary manufacturing
tolerance variations, incidental alignment variations, temporary
alignment or shape variations induced by operational conditions,
and the like.
Although the present invention has been described with reference to
preferred embodiments, workers skilled in the art will recognize
that changes may be made in form and detail without departing from
the spirit and scope of the invention. For example, the
interchangeable pump bore insert 60 and the wiper 63 disclosed
above can each be used in nearly any type of viscous clutch.
Moreover, the configuration of the fluid paths 48 and 50 described
above can be utilized in clutches having any type of desired
pumping assembly.
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