U.S. patent application number 15/263746 was filed with the patent office on 2017-03-23 for transfer case lubrication system with disengagable pump.
This patent application is currently assigned to BorgWarner Inc.. The applicant listed for this patent is BorgWarner Inc.. Invention is credited to Jesse Jongebloed, Michael Palazzolo.
Application Number | 20170082190 15/263746 |
Document ID | / |
Family ID | 56881228 |
Filed Date | 2017-03-23 |
United States Patent
Application |
20170082190 |
Kind Code |
A1 |
Jongebloed; Jesse ; et
al. |
March 23, 2017 |
Transfer Case Lubrication System with Disengagable Pump
Abstract
A lubrication system (300) for a transfer case (200) includes a
shaft (302) having a lubricant inlet port (306) and a hollow bore
(304) for transporting lubricant within the shaft (302), a pump
(310) having a pump housing (312) and one or more pumping elements
(318) that are disposed in the pump housing (312), and a clutch
assembly (330). The clutch assembly 330 has an engaged position, in
which rotational force from the shaft (302) is transferred to the
one or more pumping elements (318) to cause operation of the pump
(310), and a disengaged position, in which rotational force from
the shaft (302) is not transferred to the one or more pumping
elements (318). An actuator (370, 410) is operable to cause the
clutch assembly (330) to move between the engaged position and the
disengaged position in response to signals received from a
controller (233).
Inventors: |
Jongebloed; Jesse; (Clawson,
MI) ; Palazzolo; Michael; (Madison Heights,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BorgWarner Inc. |
Auburn Hills |
MI |
US |
|
|
Assignee: |
BorgWarner Inc.
Auburn Hills
MI
|
Family ID: |
56881228 |
Appl. No.: |
15/263746 |
Filed: |
September 13, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14857296 |
Sep 17, 2015 |
9440532 |
|
|
15263746 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16D 13/74 20130101;
B60K 17/344 20130101; F16D 2300/06 20130101; F16H 57/043 20130101;
B60K 17/3467 20130101; B60K 17/342 20130101; F16H 57/0436 20130101;
F16D 11/10 20130101; F16D 27/06 20130101; F16H 57/0434 20130101;
F16D 27/04 20130101; F16D 28/00 20130101; F16D 27/115 20130101 |
International
Class: |
F16H 57/04 20060101
F16H057/04; F16D 27/06 20060101 F16D027/06 |
Claims
1. A lubrication system (300) for a transfer case (120, 200),
comprising: a shaft (302) having a lubricant inlet port (306) and a
hollow bore (304) for transporting lubricant within the shaft
(302); a pump (310) having a pump housing (312) and one or more
pumping elements (318) that are disposed in the pump housing (312);
a clutch assembly (330) having an engaged position, in which
rotational force from the shaft (302) is transferred to the one or
more pumping elements (318) to cause operation of the pump (310),
and a disengaged position, in which rotational force from the shaft
(302) is not transferred to the one or more pumping elements (318);
and an actuator (370, 410) that is operable to cause the clutch
assembly (330) to move between the engaged position and the
disengaged position in response to signals received from a
controller (233).
2. The lubrication system (300) of claim 1, wherein the actuator
(410) is one of an electrical actuator, a hydraulic actuator, or a
pneumatic actuator.
3. The lubrication system (300) of claim 1, wherein the clutch
assembly (330) includes a first clutch rotor (340) that rotates
independent of the shaft (302) when the clutch assembly (330) is in
the disengaged position and a second clutch rotor (350) that
rotates in response to rotation of the shaft (302).
4. The lubrication system (300) of claim 3, wherein the actuator
(410) has a moveable member (412) that engages the second clutch
rotor (350) of the clutch assembly (330).
5. The lubrication system (300) of claim 4, wherein the moveable
member (412) of the actuator (410) is seated in an annular groove
(42) formed on an outer periphery of the second clutch rotor (350)
of the clutch assembly (330).
6. The lubrication system (300) of claim 4, wherein the moveable
member (412) of the actuator (410) is a shift fork.
7. The lubrication system (300) of claim 1, wherein the actuator
(370, 410) is operable to move the clutch assembly (330) in a first
direction.
8. The lubrication system (300) of claim 7, further comprising: a
biasing element (360) that is operable to move the clutch assembly
(330) in a second direction, wherein the second direction is
opposite the first direction.
9. The lubrication system (300) of claim 1, wherein the actuator
(370, 410) is operable to move the clutch assembly (330) in a first
direction and a second direction.
10. The lubrication system (300) of claim 1, wherein the actuator
is an electromagnetic coil (370) that is operable to produce a
magnetic field when energized, and energization of the
electromagnetic coil (370) causes the clutch assembly (330) to move
from the engaged position toward the disengaged position.
11. The lubrication system (300) of claim 1, wherein the actuator
is an electromagnetic coil (370) that is operable to produce a
magnetic field when energized, and energization of the
electromagnetic coil (370) causes the clutch assembly (330) to move
from the disengaged position toward the engaged position.
12. A lubrication system (300) for a transfer case (120, 200),
comprising: a shaft (302) having a lubricant inlet port (306) and a
hollow bore (304) for transporting lubricant within the shaft
(302); a pump (310) having a pump housing (312) and one or more
pumping elements (318) that are disposed in the pump housing (312);
a first clutch rotor (340) that is disposed on the shaft (302) and
is connected to the one or more pumping elements (318) such that
rotation of the first clutch rotor (340) causes operation of the
one or more pumping elements (318) of the pump (310); a second
clutch rotor (350) that rotates in response to rotation of the
shaft (302) and has an engaged position, in which rotational force
from the shaft (302) is transferred to the first clutch rotor (340)
to cause operation of the pump (310), and a disengaged position, in
which rotational force from the shaft (302) is not transferred to
the first clutch rotor (340); and an actuator (370, 410) connected
to the second clutch rotor (350) that is operable to cause the
second clutch rotor (350) to move between the engaged position and
the disengaged position.
13. The lubrication system (300) of claim 12, wherein the first
clutch rotor (340) rotates independent of the shaft (302) when the
second clutch rotor (350) is in the disengaged position.
14. The lubrication system (300) of claim 12, wherein the actuator
(410) is one of an electrical actuator, a hydraulic actuator, or a
pneumatic actuator.
15. The lubrication system (300) of claim 12, wherein the actuator
is an electromagnetic coil (370) that is operable to produce a
magnetic field when energized, and energization of the
electromagnetic coil (370) causes the second clutch rotor (350) to
move from the engaged position toward the disengaged position.
16. The lubrication system (300) of claim 12, wherein the actuator
is an electromagnetic coil (370) that is operable to produce a
magnetic field when energized, and energization of the
electromagnetic coil (370) causes the second clutch rotor (350) to
move from the disengaged position toward the engaged position.
17. A lubrication system (300) for a transfer case (120, 200),
comprising: a shaft (302) having a lubricant inlet port (306) and a
hollow bore (304) for transporting lubricant within the shaft
(302); a pump (310) having a pump housing (312) and one or more
pumping elements (318) that are disposed in the pump housing (312);
a first clutch rotor (340) that is disposed on the shaft (302) and
is connected to the one or more pumping elements (318) such that
rotation of the first clutch rotor (340) causes operation of the
one or more pumping elements (318) of the pump (310); a second
clutch rotor (350) that rotates in response to rotation of the
shaft (302) and has an engaged position, in which rotational force
from the shaft (302) is transferred to the first clutch rotor (340)
to cause operation of the pump (310), and a disengaged position, in
which rotational force from the shaft (302) is not transferred to
the first clutch rotor (340); and an electromagnetic coil (370)
that is operable to produce a magnetic field when energized and
disposed on either an axial face (348) of the first clutch rotor
(340) or an axial face (356) of the second clutch rotor (350),
wherein energization of the electromagnetic coil (370) causes the
second clutch rotor (350) to move between the engaged position and
the disengaged position.
18. The lubrication system (300) of claim 17, energization of the
electromagnetic coil (370) causes the second clutch rotor (350) to
move from the engaged position toward the disengaged position.
19. The lubrication system (300) of claim 17, energization of the
electromagnetic coil (370) causes the second clutch rotor (350) to
move from the disengaged position toward the engaged position.
20. The lubrication system (300) of claim 17, wherein the
electromagnetic coil (370) causes the second clutch rotor (350) to
move in a first direction between the engaged position and the
disengaged position, and a biasing element (360) causes the second
clutch rotor (350) to move in a second direction between the
engaged position and the disengaged position.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/857,296, filed on Sep. 17, 2015.
BACKGROUND
[0002] In the field of vehicle drivetrain components, a transfer
case is an apparatus that distributes driving power to more than
one driven axle of the vehicle. A typical transfer case receives
driving power from the transmission of the vehicle and transfers
that power to a primary output shaft and a secondary output shaft,
with the secondary output shaft being driven selectively using a
clutch. In addition, two speed transfer cases provide gear
reduction to allow operation in a high range, which is typically a
1:1 drive ratio, or a low range, such as a 2:1 drive ratio.
[0003] Many of the components in a transfer case require
lubrication. One transfer case design includes a pump that is
mounted on one of the input shaft or the primary output shaft. The
pump delivers lubricant to the various components of the transfer
case through an axial bore that is formed through the input shaft
and/or the output shaft. Supply ports are formed through the input
shaft and/or the output shaft at locations where lubrication is
needed, such that the lubricant flows from the pump, through the
axial bore, and out of the supply ports. This arrangement is
effective but offers little control over the rate of lubricant flow
to specific components.
SUMMARY
[0004] One aspect of the disclosed embodiments is a lubrication
system for a transfer case. The lubrication system includes a shaft
having a lubricant inlet port and a hollow bore for transporting
lubricant within the shaft. A pump has a pump housing and one or
more pumping elements that are disposed in the pump housing. A
clutch assembly has an engaged position, in which rotational force
from the shaft is transferred to the one or more pumping elements
to cause operation of the pump, and a disengaged position, in which
rotational force from the shaft is not transferred to the one or
more pumping elements. An actuator is operable to cause the clutch
assembly to move between the engaged position and the disengaged
position in response to signals received from a controller.
[0005] In another disclosed embodiment, a lubrication system for a
transfer case includes a shaft having a lubricant inlet port and a
hollow bore for transporting lubricant within the shaft. A pump has
a pump housing and one or more pumping elements that are disposed
in the pump housing. A first clutch rotor that is disposed on the
shaft and is connected to the one or more pumping elements such
that rotation of the first clutch rotor causes operation of the one
or more pumping elements of the pump. A second clutch rotor that
rotates in response to rotation of the shaft and has an engaged
position, in which rotational force from the shaft is transferred
to the first clutch rotor to cause operation of the pump, and a
disengaged position, in which rotational force from the shaft is
not transferred to the first clutch rotor. An actuator is connected
to the second clutch rotor that is operable to cause the second
clutch rotor to move between the engaged position and the
disengaged position.
[0006] In yet another disclosed embodiment, a lubrication system
for a transfer case includes a shaft having a lubricant inlet port
and a hollow bore for transporting lubricant within the shaft. A
pump has a pump housing and one or more pumping elements that are
disposed in the pump housing. A first clutch rotor that is disposed
on the shaft and is connected to the one or more pumping elements
such that rotation of the first clutch rotor causes operation of
the one or more pumping elements of the pump. A second clutch rotor
that rotates in response to rotation of the shaft and has an
engaged position, in which rotational force from the shaft is
transferred to the first clutch rotor to cause operation of the
pump, and a disengaged position, in which rotational force from the
shaft is not transferred to the first clutch rotor. An
electromagnetic coil that is operable to produce a magnetic field
when energized and disposed on either an axial face of the first
clutch rotor or an axial face of the second clutch rotor, wherein
energization of the electromagnetic coil causes the second clutch
rotor to move between the engaged position and the disengaged
position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The description herein makes reference to the accompanying
drawings, wherein like referenced numerals refer to like parts
throughout several views, and wherein:
[0008] FIG. 1 is a plan view illustration showing a drivetrain that
includes a transfer case;
[0009] FIG. 2 is a cross-section illustration showing a transfer
case;
[0010] FIG. 3 is an illustration of a lubrication system for a
transfer case according to a first example; and
[0011] FIG. 4 is an illustration of a lubrication system for a
transfer case according to a second example.
DETAILED DESCRIPTION
[0012] The disclosure herein is directed to a lubrication system
for a transfer case in which one or more pumping elements are
configured to be connected to and disconnected from a rotating
shaft. This allows the pump to be disengaged such that it stops
pumping a lubricant under certain conditions, which reduces the
parasitic loss associated with driving the pumping elements using
the rotating shaft.
[0013] FIG. 1 shows a drivetrain 100 for a four-wheel drive
vehicle. The drivetrain 100 includes an engine 110 that is coupled
to a transmission 112. The engine 110 is the prime mover of the
drivetrain 100 and can be, as examples, an internal combustion
engine, an electric motor/generator, or a combination of the two.
Other types of prime movers can be utilized as the engine 110 to
provide driving power (e.g. via a rotating output shaft) to the
transmission 112. The transmission 112 includes components operable
to convert the speed and torque of the driving power provided by
the engine 110, such as by a gear train that provides multiple gear
ratios. As examples, the transmission 112 can be a manual
transmission, an automatic transmission, a semi-automatic
transmission, a continuously variable transmission, or a dual
clutch transmission.
[0014] The transmission 112 provides driving power to a transfer
case 120. The transfer case 120 is operable to distribute driving
power to a rear driveshaft 130 and a front driveshaft 140.
[0015] The transfer case 120 can, in some implementations, include
components that allow the transfer case 120 to perform a mode shift
between two or more different modes. For example, the transfer case
120 can allow operation in a rear-wheel drive mode, in which the
rear driveshaft 130 receives driving power and the front driveshaft
140 does not, and a four-wheel drive mode, in which the rear
driveshaft 130 and the front driveshaft 140 both receive driving
power. In this example, the rear driveshaft 130 is the primary
driveshaft and the front driveshaft 140 is the secondary
driveshaft. In other implementations, the front driveshaft 140 is
the primary driveshaft and the rear driveshaft 130 is the secondary
driveshaft, and the transfer case 120 performs a mode shift between
a front-wheel drive mode and a four-wheel drive mode. In other
implementations the transfer case 120 does not include components
that allow a mode shift, and the transfer case 120 constantly
provides driving power to both of the rear driveshaft 130 and the
front driveshaft 140.
[0016] The transfer case 120 can allow a range shift that
selectively provides gear reduction to the rotational output of the
transfer case 120. For example, the transfer case 120 can include
components for operating in a high range, such as a 1:1 drive
ratio, or a low range, such as a 2:1 drive ratio. The range shift
changes the transfer case 120 between operation in the low range
and the high range by selectively coupling and uncoupling a gear
reduction mechanism of the transfer case 120.
[0017] Operation of the transfer case 120 can be regulated by a
controller such as an ECU 122 that provides signals to components
of the transfer case 120 to cause the mode shift and/or the range
shift. In other implementations, the mode shift and/or the range
shift can be actuated mechanically such as by a driver-operated
lever that is mechanically connected to a component of the transfer
case 120.
[0018] The rear driveshaft 130 provides driving power to a rear
axle 150 via a rear differential 152. The rear axle 150 can be, as
examples, a solid axle or a pair of independent half axles. The
rear axle 150 provides driving power to a pair of rear wheels 154
that are fitted with tires.
[0019] The front driveshaft 140 provides driving power to a front
axle 160 via a front differential 162. The front axle 160 can be,
as examples, a solid axle or a pair of independent half axles. The
front axle 160 provides driving power to a pair of front wheels 164
that are fitted with tires.
[0020] FIG. 2 shows the transfer case 200, which is conventional.
The transfer case 200 includes a housing 202, an input shaft 204
that extends out of the housing 202, a primary output shaft 206
that extends out of the housing 202, and a secondary output shaft
208 that extends out of the housing 202. The input shaft 204 and
the primary output shaft 206 extend along a first axis 207. The
secondary output shaft 208 extends along a second axis 209 which
is, in this example, parallel to the first axis 207.
[0021] The input shaft 204 is at least partially hollow, and the
primary output shaft 206 extends into the hollow interior of the
input shaft 204. The input shaft 204 can be connected to the
primary output shaft either directly, or via a gear reduction
mechanism 210. The gear reduction mechanism 210 can be a Ravigneaux
planetary gearset that includes a sun gear 212 formed on the input
shaft 204, a plurality of planet gears 214, and a ring gear 216
that is fixed to the housing 202. A planet carrier 218 is arranged
on the input shaft 204 and can rotate about the input shaft 204.
The planet gears 214 are arranged on stub shafts 220 that are
connected to the planet carrier 218. The planet gears 214 mesh with
the sun gear 212 and the ring gear 216.
[0022] A dog clutch 222 is utilized to engage and disengage the
gear reduction mechanism 210. In a first position of the dog clutch
222, the dog clutch 222 engages the input shaft 204 and the primary
output shaft 206 directly, which establishes a 1:1 drive ratio and
does not utilize the gear reduction mechanism 210. In a second
position of the dog clutch 222 (not shown), the dog clutch 222 is
shifted axially away from the input shaft 204, and instead engages
the planet carrier 218 and the primary output shaft 206. Driving
power is thus routed through the gear reduction mechanism 210, with
the planet carrier rotating slower to than the input shaft 204 to
establish a drive ratio such as 2:1.
[0023] The dog clutch 222 is moved between its first and second
positions by a first selector fork 224, which moves axially along a
selector shaft 226. A first cam follower 228 is formed on the first
selector fork 224. The first cam follower 228 is disposed in a
first groove 230 formed on an exterior surface of a barrel cam 232.
The barrel cam 232 is disposed on a rotatable shaft 234 that is
rotated be an electric motor 236 in response to control signals
from a controller, such as the ECU 122 of FIG. 1.
[0024] The transfer case 200 includes a pump 240 for pumping a
lubricant (not shown) to components of the transfer case 200 that
require lubrication. The pump 240 is arranged on the primary output
shaft 206 and a pump mechanism of the pump 240 is driven by the
primary output shaft 206. The pump 240 can be, for example, a
gerotor pump. Other types of pumping mechanisms can be utilized. At
least a portion of the housing 202 can serve as a sump, and the
pump 240 can include a conduit 242 that extends into the sump area
of the housing 202.
[0025] To route lubrication to various components of the transfer
case 200, the primary output shaft includes an axially extending
hollow bore 244 and a plurality of lubricant ports, each of which
extends radially through the primary output shaft 206. The
plurality of lubricant ports can include an inlet port 246 and one
or more outlet ports 248. The inlet port 246 is aligned with an
outlet of the pump 240 and receives the lubricant under pressure
from the pump 240. The outlet ports 248 are positioned along the
primary output shaft 206 near components that require lubrication.
The lubricant is pressurized by the pump 240, travels through the
inlet port 246, along the hollow bore 244, and out of one of the
outlet ports 248 to lubricate portions of the transfer case 200.
Excess lubricant then drains to the sump area inside the housing
202.
[0026] A first sprocket 250 is arranged on the primary output shaft
206 and is connected to the primary output shaft by a clutch 252. A
second sprocket 254 is arranged on the secondary output shaft 208
and connected for rotation in unison, such as by splines. The first
sprocket 250 and the second sprocket 254 are connected by a chain
256, such that the second output shaft is driven by the primary
output shaft 206 via the first sprocket 250, the chain 256 and the
second sprocket 254 when the clutch 252 is engaged. The clutch 252
includes, for example, a clutch pack 253 of interleaved plates,
with the clutch being engaged when pressure is applied to the
clutch pack 253 by an electromagnetic actuator 258. In the
illustrated example, the clutch 252 can allow active control of
distribution of power between the primary output shaft 206 and the
secondary output shaft 208. In alternative implementations,
different types of clutches and other mechanisms can be utilized to
control transfer of power to the secondary output shaft 208. Thus,
for example, the transfer case 200 could be configured to simply
couple or decouple the first sprocket 250 with respect to the
primary output shaft 206, as in well-known part-time/manual
transfer cases.
[0027] FIG. 3 shows a lubrication system 300 that includes a pump
310 that is located on and driven by a shaft 302. The lubrication
system 300 can be implemented in a transfer case of any suitable
configuration. For example, the lubrication system 300 can be
implemented in the transfer case 200 in place of the pump 240.
Thus, the lubrication system 300 could be disposed on one of the
input shaft 204 or the primary output shaft 206 of the transfer
case 200.
[0028] The shaft 302 is a rotating member that has a hollow bore
304 for transporting lubricant within the shaft 302 from one or
more fluid inlets 306 to one or more fluid outlets (not shown). The
one or more fluid inlets 306 and the one or more fluid outlets
extend radially through the shaft 302.
[0029] The pump 310 includes a pump housing 312. The shaft 302
passes through the pump housing through an aperture 314 that
extends through the pump housing 312. The pump housing 312 is
mounted in a manner that restrains the pump housing 312 from
rotating in response to rotation of the shaft 302. For instance,
the pump housing 312 can be connected to a fixed structure 316 such
that the pump housing 312 does not rotate in response to rotation
of the shaft 302. In implementations where the lubrication system
300 is implemented in a transfer case such as the transfer case
200, the pump housing 312 can be fixed to the housing 202.
[0030] The pump 310 includes one or more pumping elements that are
disposed in the pump housing 312 and are operated by rotational
force provided by rotation of the shaft 302. In the illustrated
example, the pump 310 is a gerotor pump, and the one or more
pumping elements include an inner pump rotor 318 that is located on
the shaft 302, and an outer pump rotor 320, which is an annular
member that extends around the inner pump rotor 318. As in
conventional gerotor pumps, the inner pump rotor 318 includes a
first plurality of teeth and the outer pump rotor 320 includes a
second plurality of teeth in greater number than the first
plurality of teeth. Typically, the outer pump rotor 320 will
include teeth in a number that is one greater than the number of
teeth on the inner pump rotor 318. Rotation of the inner pump rotor
318 causes rotation of the outer pump rotor 320 through meshing of
their respective teeth, which creates a low pressure inlet region
where the teeth diverge and a high pressure outlet region where the
teeth converge. The inlet region can be in communication with a
source of fluid (e.g. lubricant such as transmission fluid or oil)
and the outlet region can be in communication with at least one of
the fluid inlets 306 of the shaft 302 to pump pressurized fluid
into the hollow bore 304 of the shaft via the fluid inlets 306. As
will be explained further herein the pumping elements of the pump
310 are not driven directly by the shaft 302. Instead, the inner
pump rotor 318 is disposed on the shaft 302 such that the shaft 302
may rotate independent of rotation of the inner pump rotor 318.
[0031] In order to provide a rotational input force to the pump
310, the lubrication system 300 includes a clutch assembly 330. The
clutch assembly 330 has an engaged position in which rotational
force is transferred from the shaft 302 to the inner pump rotor
318, and a disengaged position in which rotational force is not
transferred from the shaft 302 to the inner pump rotor 318.
[0032] The clutch assembly 330 has a first clutch rotor 340 and a
second clutch rotor 350. The first clutch rotor 340 rotates in
unison with the inner pump rotor 318, while the second clutch rotor
350 rotates in unison with the shaft 302. The second clutch rotor
350 causes rotation of the first clutch rotor 340 in the engaged
position but does not cause rotation of the first clutch rotor 340
in the disengaged position by virtue of a small air gap by which
the first clutch rotor 340 is spaced from the second clutch rotor
350. The clutch assembly 330 may further define a fully engaged
position in which the first clutch rotor 340 and the second clutch
rotor 350 rotate in unison, and a partially engaged position in
which the second clutch rotor 350 contacts the first clutch rotor
340 but slips with respect to it such that the first clutch rotor
340 rotates slower than the second clutch rotor 350.
[0033] The first clutch rotor 340 is disposed on the shaft 302 such
that the shaft 302 may rotate independent of the first clutch rotor
340. In the illustrated example, the first clutch rotor 340 is
supported with respect to the shaft 302 by one or more bearings
332. The second clutch rotor 350 can include a cylindrical portion
342 in the form of a tube with the shaft 302 passing through it.
The cylindrical portion 342 is connected to the inner pump rotor
318 of the pump 310, and extends out of the pump housing 312
axially along the shaft 302. Opposite the inner pump rotor 318, the
first clutch rotor 340 can include a disk portion 344 that extends
radially outward from the cylindrical portion 342. In the
illustrated example, the disk portion 344 is planar, lies in a
plane that is perpendicular to the longitudinal axis of the shaft
302, and has an axial face 348 that is oriented toward the second
clutch rotor 350. In the illustrated example, the first clutch
rotor 340 also includes an annular rim 346 that extends from the
outer end of the disk portion 344 and is concentric to the
cylindrical portion 342.
[0034] The second clutch rotor 350 is positioned along the shaft
302 such that the first clutch rotor 340 is located between the
pump 310 and the second clutch rotor 350. The second clutch rotor
350 is mounted to the shaft 302 such that it rotates substantially
in unison with the shaft 302, but is able to slide axially along
the shaft 302 at least over a limited distance. The distance by
which the second clutch rotor 350 is able to slide axially along
the shaft 302 is at least sufficient to allow the second clutch
rotor 350 to move into and out of engagement with the first clutch
rotor 340.
[0035] The second clutch rotor 350 includes a cylindrical portion
352 that is seated on the shaft 302 such that the shaft 302 passes
through it. The cylindrical portion 352 can be connected to the
shaft 302 by splines (not shown) to enforce uniform rotation with
the shaft 302 while permitting axial sliding, or by any other
suitable structure. A disk portion 354 is connected to and
supported by the cylindrical portion 352. In the illustrated
example, the disk portion defines a maximum diameter for the second
clutch rotor 350 that is similar to a maximum diameter for the
first clutch rotor 340, as defined by the disk portion 344 and/or
the annular rim 346 of the second rotor.
[0036] An axial face 356 of the second clutch rotor 350 faces the
first clutch rotor 340. Optionally, the axial face 356 of the
second clutch rotor 350 can be defined by a high friction
material.
[0037] The lubrication system 300 includes a biasing element that
is operable to apply a spring force to the second clutch rotor 350.
In the illustrated example, the biasing element is an annular
member that is seated on the shaft 302, such as a wave spring 360
that exerts a spring force on the second clutch rotor 350 when
compressed by engagement of cylindrical portion 352 of the second
clutch rotor 350 with the wave spring 360. Thus, the wave spring
360 can be a compression spring. The wave spring 360 is located on
the shaft 302 between the second clutch rotor 350 and a stop member
362, such as a surface defined on the shaft 302 or a stop ring that
is seated on the shaft 302 such that it cannot move axially with
respect to the shaft 302. In the illustrated example, the stop
member 362 is located on the shaft 302 between the first clutch
rotor 340 and the second clutch rotor 350. Thus, the wave spring
360 urges the second clutch rotor 350 axially away from the first
clutch rotor 340 toward the disengaged position of the clutch
assembly 330, such that the small air gap is defined between the
axial face 348 of the first clutch rotor 340 and the axial face 356
of the second clutch rotor 350.
[0038] To move the clutch assembly 330 between the disengaged
position and the engaged position, the clutch assembly 330 includes
an actuator in the form of an electromagnetic coil 370. The
electromagnetic coil 370 receives electricity from an external
power source (not shown) that can be energized and de-energized. In
the illustrated example, the electromagnetic coil 370 is disposed
on the first clutch rotor 340 on the disk portion 344 opposite the
axial face 348, such that the electromagnetic coil 370 is directly
behind the axial face 348 of the first clutch rotor 340.
[0039] In one implementation, the electromagnetic coil 370 can be
energized to create a magnetic field that attracts ferromagnetic
objects. In this implementation, all or part of the second clutch
rotor 350 is formed from a ferromagnetic material. Thus, when the
electromagnetic coil 370 is energized, the second clutch rotor 350
is moved axially toward the first clutch rotor 340 as a result of
the magnetic field, while compressing the wave spring 360. When the
electromagnetic coil 370 is de-energized, magnetic attraction
ceases, and the biasing force applied to the second clutch rotor
350 by the wave spring 360 moves the second clutch rotor 350
axially along the shaft 302 to place the clutch assembly 330 in the
disengaged position. Thus, in this implementation, the clutch
assembly 330 is in the disengaged position when the electromagnetic
coil 370 is de-energized, and the clutch assembly 330 is in the
engaged position when the electromagnetic coil 370 is
energized.
[0040] In an alternative implementation, the operating relationship
between energization of the electromagnetic coil 370 and engagement
of the clutch assembly 330 can be reversed. In this implementation,
the first clutch rotor 340 is formed from a ferromagnetic material
and magnets (not shown) are disposed on the second clutch rotor
350. When the electromagnetic coil 370 is not energized, the
magnets on the second clutch rotor 350 are attracted to the first
clutch rotor 340 to move the second clutch rotor 350 into
engagement with the first clutch rotor 340 to place the clutch
assembly 330 in the engaged position. The electromagnetic coil 370
is configured such that the polarity of the magnetic field it
produces cancels the magnetic attractive force exerted on the first
clutch rotor 340 by the magnets on the second clutch rotor 350. The
magnetic attraction is diminished sufficiently such that the
biasing force of the wave spring 360 is no longer overcome. As a
result, the second clutch rotor 350 is moved away from the first
clutch rotor 340 by the wave spring 360 to place the clutch
assembly 330 in the disengaged position. Thus, in this
implementation, the clutch assembly 330 is in the engaged position
when the electromagnetic coil 370 is de-energized, and the clutch
assembly 330 is in the disengaged position when the electromagnetic
coil 370 is energized.
[0041] In operation, a determination is made as to whether or not
to operate the pump 310 of the lubrication system 300. The
determination can be made by a controller, such as the ECU 122 of
the drivetrain 100, based on, for example, operating conditions of
the drivetrain 100. If the pump is to be operated, the clutch
assembly 330 is moved to the engaged position by, for example,
energizing the electromagnetic coil 370. This moves the second
clutch rotor 350 axially into engagement with the first clutch
rotor 340. As a result of this engagement, the first clutch rotor
340 and the pumping elements of the pump 310 begin to rotate. In
some implementations, full engagement results, and the rotational
speed of the first clutch rotor 340 matches the rotational speed of
the second clutch rotor 350. Rotation of the first clutch rotor 340
causes rotation of the pumping elements of the pump 310, which
results in fluid being pumped by the pump 310. When operation is no
longer needed, the electromagnetic coil 370 is de-energized and the
second clutch rotor 350 is moved out of engagement with the first
clutch rotor 340 by the wave spring 360.
[0042] FIG. 4 shows a lubrication system 400 according to an
alternative implementation. The lubrication system 400 is similar
to the lubrication system 300 and includes all elements of the
lubrication system 300 except as noted herein.
[0043] The lubrication system 400 omits the electromagnetic coil
370 that was described in connection with the lubrication system
300. To move the clutch assembly 330 between the engaged position
and the disengaged position, the lubrication system 400 includes an
actuator 410 that has a moving member 412. The moving member 412 is
engaged with the second clutch rotor 350 to move the second clutch
rotor 350. In the illustrated example, the moving member 412 is
seated in an annular groove 420 formed on an outer periphery of the
second clutch rotor 350.
[0044] The actuator 410 can be operable to move the second clutch
rotor 350 in a single axial direction only, in which case the wave
spring 360 acts opposite the actuator 410, or in both axial
directions, in which case the wave spring 360 and the stop member
362 can be omitted.
[0045] The actuator 410 can be any suitable type of actuator, such
as an electrical actuator, a hydraulic actuator, or a pneumatic
actuator. In one implementation, the moving member 412 is a shift
fork that is moved in the axial direction of the shaft 302 by a
barrel cam that is rotated by an electrical motor, such as the
barrel cam 232 of the transfer case 200 and the electric motor 236
of the transfer case 200.
[0046] Operation of the lubrication system 400 is similar to
operation of the lubrication system 300, as previously
described.
[0047] While the disclosure has been made in connection with what
is presently considered to be the most practical and preferred
embodiment, it should be understood that the disclosure is intended
to cover various modifications and equivalent arrangements.
* * * * *