U.S. patent application number 17/404479 was filed with the patent office on 2021-12-02 for dual actuating variable cam.
The applicant listed for this patent is BorgWarner Inc.. Invention is credited to Xiaoyu LU, Chad MCCLOY.
Application Number | 20210372302 17/404479 |
Document ID | / |
Family ID | 1000005783083 |
Filed Date | 2021-12-02 |
United States Patent
Application |
20210372302 |
Kind Code |
A1 |
MCCLOY; Chad ; et
al. |
December 2, 2021 |
DUAL ACTUATING VARIABLE CAM
Abstract
A variable camshaft timing system including a first camshaft
phaser having an input that is configured to receive rotational
force from a crankshaft and an output that is configured to link
with a first camshaft of a concentric camshaft assembly to change
the angular position of the first camshaft relative to a
crankshaft; and a second camshaft phaser having an output that is
configured to link with a second camshaft of the concentric
camshaft assembly to change the angular position of the second
camshaft relative to the crankshaft, wherein the first camshaft is
concentrically positioned to the first camshaft and the first
camshaft phaser is mechanically linked to the second camshaft
phaser to communicate rotational force from the crankshaft to the
second camshaft phaser through the first camshaft phaser and the
mechanical link.
Inventors: |
MCCLOY; Chad; (Cortland,
NY) ; LU; Xiaoyu; (Lansing, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BorgWarner Inc. |
Auburn Hills |
MI |
US |
|
|
Family ID: |
1000005783083 |
Appl. No.: |
17/404479 |
Filed: |
August 17, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16263025 |
Jan 31, 2019 |
11125121 |
|
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17404479 |
|
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62632728 |
Feb 20, 2018 |
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62625613 |
Feb 2, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01L 1/352 20130101;
F01L 2250/02 20130101; F01L 2001/34486 20130101; F01L 2820/033
20130101; F01L 2001/34493 20130101; F01L 1/047 20130101; F01L
2250/04 20130101; F01L 2820/032 20130101; F01L 2001/0473 20130101;
F01L 2311/00 20200501; F16D 3/10 20130101; F01L 2001/0537
20130101 |
International
Class: |
F01L 1/352 20060101
F01L001/352; F01L 1/047 20060101 F01L001/047; F16D 3/10 20060101
F16D003/10 |
Claims
1. A variable camshaft timing system, comprising: a first camshaft
phaser comprising a hydraulically-actuated camshaft phaser having a
first housing, an input that is configured to receive rotational
force from a crankshaft, and an output that is configured to link
with a first camshaft of a concentric camshaft assembly to change
the angular position of the first camshaft relative to a
crankshaft; and a second camshaft phaser comprising a
hydraulically-actuated camshaft phaser having a second housing and
an output that is configured to link with a second camshaft of the
concentric camshaft assembly to change the angular position of the
second camshaft relative to the crankshaft, wherein the first
camshaft is concentrically positioned to the second camshaft and
the first camshaft phaser is mechanically linked to the second
camshaft phaser to communicate rotational force from the crankshaft
to the second camshaft phaser through the first camshaft phaser and
the mechanical link.
2. The variable camshaft timing system recited in claim 1, further
comprising a flex plate that couples the first camshaft phaser to
the second camshaft phaser.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Patent
Application No. 62/625613 filed on Feb. 2, 2018, U.S. Patent
Application No. 62/632728 filed on Feb. 20, 2018, the disclosures
of which are herein incorporated by reference in their entirety,
and U.S. patent application Ser. No. 16/263,025 filed Jan. 31,
2019.
TECHNICAL FIELD
[0002] The present application relates to internal combustion
engines and, more particularly, to variable camshaft timing of
camshafts used with internal combustion engines.
BACKGROUND
[0003] Internal combustion engines (ICEs) use one or more camshafts
to open and close intake and exhaust valves in response to cam
lobes selectively actuating valve stems as the camshaft(s) rotate
overcoming the force of valve springs that keep the valves seated
and displacing the valves. The shape and angular position of the
cam lobes can affect the operation of the ICE. In the past, the
angular position of the camshaft relative to the angular position
of the crankshaft was fixed. But it is possible to vary the angular
position of the camshaft relative to the crankshaft using variable
camshaft timing (VCT). VCT can be implemented using camshaft
phasing devices (sometimes referred to as cam phasers) that change
the angular position of the camshaft relative to the crankshaft.
These cam phasers can be hydraulically- or electrically-actuated
and are typically directly attached to one end of the camshaft.
[0004] Concentric camshafts including an inner camshaft and an
outer camshaft can be used to vary the angular position of the
inner camshaft relative to the outer camshaft. Typically, one of
the concentric camshafts (the inner camshaft or outer camshaft) has
a fixed angular position relative to the angular position of the
crankshaft. The angular position of the other concentric camshaft
is then varied relative to the camshaft with the fixed relative
angular position. However, modern internal combustion engines
(ICEs) benefit from increasingly flexible variable camshaft timing
configurations. It would be helpful to increase the amount of
control over the angular positions of the inner camshaft and the
outer camshaft relative to the crankshaft.
SUMMARY
[0005] In one embodiment, a variable camshaft timing system
includes a first camshaft phaser having an input that is configured
to receive rotational force from a crankshaft and an output that is
configured to link with a first camshaft of a concentric camshaft
assembly to change the angular position of the first camshaft
relative to a crankshaft; and a second camshaft phaser having an
output that is configured to link with a second camshaft of the
concentric camshaft assembly to change the angular position of the
second camshaft relative to the crankshaft, wherein the first
camshaft is concentrically positioned to the second camshaft and
the first camshaft phaser is mechanically linked to the second
camshaft phaser to communicate rotational force from the crankshaft
to the second camshaft phaser through the first camshaft phaser and
the mechanical link.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a profile view depicting an implementation of a
variable camshaft timing (VCT) system including a
hydraulically-actuated camshaft phaser, an electrically-actuated
camshaft phaser, and a concentric camshaft assembly;
[0007] FIG. 2 is a perspective view depicting an implementation of
the hydraulically-actuated camshaft phaser and the
electrically-actuated camshaft phaser of the VCT system shown in
FIG. 1;
[0008] FIG. 3 is a cross-sectional profile view depicting an
implementation of the hydraulically-actuated camshaft phaser and
the electrically-actuated camshaft phaser of the VCT system shown
in FIG. 1;
[0009] FIG. 4 is an exploded view depicting an implementation of
the hydraulically-actuated camshaft phaser and the
electrically-actuated camshaft phaser of the VCT system shown in
FIG. 1;
[0010] FIG. 5 is a cross-sectional profile view depicting another
implementation of a VCT system including two electrically-actuated
camshaft phasers and a concentric camshaft assembly;
[0011] FIG. 6 is a cross-sectional profile view depicting another
implementation of a VCT system including two electrically-actuated
camshaft phasers and a concentric camshaft assembly; and
[0012] FIG. 7 is a cross-sectional profile view depicting another
implementation of a VCT system including a hydraulically-actuated
camshaft phaser, an electrically-actuated camshaft phaser, and a
concentric camshaft assembly;
[0013] FIG. 8 is an exploded view depicting an implementation of a
first hydraulically-actuated camshaft phaser and a second
hydraulically-actuated camshaft phaser.
DETAILED DESCRIPTION
[0014] A variable camshaft timing (VCT) system includes a plurality
of variable camshaft timing devices (also referred to as camshaft
phasers) that control the angular position of an inner camshaft and
an outer camshaft included in a concentric camshaft assembly
relative to a crankshaft. A first camshaft phaser and a second
camshaft phaser each include an input and an output. The input of
the first camshaft phaser can be driven by the crankshaft via a
crankshaft sprocket. The input of the second camshaft phaser can be
mechanically linked with the first camshaft phaser such that the
rotational force from the crankshaft is communicated to the second
camshaft phaser through the first camshaft phaser.
[0015] The mechanical link between the first camshaft phaser and
the second camshaft phaser can be made directly such that a portion
of the first camshaft phaser engages or couples with a portion of
the second camshaft phaser without using an endless loop. The
output of the first camshaft phaser can be coupled with a first
camshaft of the concentric camshaft assembly and an output of the
second camshaft phaser can be coupled with a second camshaft of the
concentric camshaft assembly. The VCT system can then rotate or
drive the first camshaft and the second camshaft (e.g., the outer
camshaft and the inner camshaft) using the rotational energy from
the crankshaft and also change the angular position of the first
camshaft and the angular position of the second camshaft
independently from each other. The first camshaft phasers and
second camshaft phasers can be implemented using two
electrically-actuated camshaft phasers, two hydraulically-actuated
camshaft phasers, or one electrically-actuated camshaft phaser and
one hydraulically-actuated camshaft phaser. Further, the first
camshaft phaser and the second camshaft phaser can be positioned
radially apart from each other or the first camshaft phaser and the
second camshaft phaser can be positioned on a common axis adjacent
to each other such that the rotation of the first camshaft phaser
is coaxial with the rotation of the second camshaft phaser.
[0016] Turning to FIGS. 1-4, an implementation of a variable
camshaft timing system (VCT) 100 is shown. The VCT system 100
includes a first camshaft 102 and a second camshaft 104 that are
concentric to each other forming a concentric camshaft assembly
106. Concentric camshafts are known by those skilled in the art, an
example of which is shown in FIG. 1 of U.S. Pat. No. 8,186,319 and
described in column 6, lines 10-53; the contents of that portion of
U.S. Pat. No. 8,186,319 are incorporated by reference. A first
camshaft phaser 108 is coupled with the first camshaft 102 and a
second camshaft phaser 110 is coupled with the second camshaft 104.
The first camshaft phaser 108 is implemented using a
hydraulically-actuated camshaft phaser and the second camshaft
phaser 110 is implemented using an electrically-actuated camshaft
phaser. The first camshaft phaser 108 includes an input and an
output. The input of the first camshaft phaser 108 is received by a
housing 112 and the output is coupled with the first camshaft (e.g.
the outer camshaft). The input of the second camshaft phaser 110 is
also received via the housing 112 and the output is coupled with
the second camshaft (e.g. the inner camshaft 104). It should be
appreciated that, in other implementations, the output of a first
camshaft phaser can be coupled with an inner camshaft and the
output of a second camshaft phaser can be coupled with an outer
camshaft.
[0017] The first camshaft phaser 108 includes a rotor 114, and a
stator 116 that is included in a portion of the housing 112. The
housing 112 can include a hydraulically-actuated phaser portion 117
and an electrically-actuated phaser portion 119. The
hydraulically-actuated phaser portion 117 can receive the rotor 114
of the first camshaft phaser 108 and act as the stator 116. The
housing 112 can include an inner plate 113 and an outer plate 115
that axially constrain the rotor 114 and at least partially define
one or more fluid chambers used with the rotor 114. The
electrically-actuated phaser portion 119 can engage a mechanical
gearbox 118 that changes the angular position of the output of the
second camshaft phaser 110 relative to the input of the second
camshaft phaser 110. The housing 112 can mechanically link the
first camshaft phaser 108 with the second camshaft phaser 110. In
this implementation, the first camshaft phaser 108 can be coupled
to the second camshaft phaser 110 by mechanically fastening a flex
plate 121 attached to the second camshaft phaser 110 with the
hydraulically-actuated phaser portion 117 of the housing 112 using
any one of a number of fastening techniques, such as threaded
bolts. The flex plate 121 can permit angular deflection of the
first camshaft 102 and the first camshaft phaser 108 relative to
the second camshaft 104 and the second camshaft phaser 110 such
that the concentric camshafts may be displaced relative to each
other due to misalignment. In addition, the housing 112 can include
a plurality of radially-outwardly facing gear teeth 120. An endless
loop (not shown), such as a chain or a belt, can engage both the
teeth of a crankshaft sprocket (not shown) and the gear teeth 120
of the housing 112 thereby transmitting the rotational force from a
crankshaft to the housing 112.
[0018] The rotor 114 of the first camshaft phaser 108 can be
coupled with the output of the first camshaft phaser 108 such that
the rotor 114 and the outer camshaft 102 are angularly fixed
relative to each other. The rotor 114 includes one or more vanes
124 that extend radially outwardly from a hub 126 into fluid
chamber(s) 128 of the stator 116. The stator 116 includes fluid
chambers 128 in the housing 112 within which the vanes 124 move
angularly with respect to the stator 116 about an axis. Pressurized
fluid can be supplied from a fluid source (not shown) through a
plurality of fluid supply lines 130 to the fluid chambers 128. In
this implementation, the fluid supply lines 130 pass through a
camshaft 136 and communicate pressurized fluid, such as engine oil,
to the fluid chambers 128 in the housing 112. To move the rotor 114
relative to the stator 116 in one angular direction, the
pressurized fluid can be directed through a first fluid supply line
132 to one side of the vane(s) 124 and to move the rotor 114
relative to the stator 116 in another angular direction, the
pressurized fluid can be directed through a second fluid supply
line 134 to an opposite side of the vane(s) 124. A range of
authority can be defined by the angular distance the fluid chambers
128 permit the rotor 114 to move relative to the housing 112.
[0019] The second camshaft phaser 110 includes a mechanical gearbox
118 having a sun gear 138, a plurality of planetary gears 140, and
at least one ring gear 142. The electrically-actuated phaser
portion 119 of the housing 112 can include the ring gear 142 having
a plurality of radially-inwardly facing gear teeth 144. The inner
camshaft 104 can be coupled with a sprocket gear 146 that includes
a plurality of gear teeth 144 on a radially-inwardly facing
surface. The plurality of planetary gears 140 can each include a
plurality of gear teeth 144 on a radially outwardly facing surface
that engage both the ring gear 142 of the housing 112 as well as
the sprocket gear 146 coupled with the inner camshaft 104. The sun
gear 138 can include gear teeth on a radially-outwardly facing
outer surface and be positioned radially-inwardly from the
planetary gears 140 such that the sun gear 138 engages the
planetary gears 140. An electric motor 148 can be coupled to the
sun gear 138 through an output shaft.
[0020] As the crankshaft rotates during engine operation, the
housing 112 rotates in response to the rotation of the endless
loop. The first camshaft phaser 108 can alter the angular position
of the outer camshaft 102 relative to the crankshaft and the second
camshaft phaser 110 can alter the angular position of the inner
camshaft 104 relative to the crankshaft. With respect to the
hydraulically-actuated first camshaft phaser 108, the rotor 114 can
be mechanically locked into place with reference to the housing
112, such as by engaging a locking pin, thereby fixing the angular
position of the rotor 114 relative to the stator 116 and, thus, the
outer camshaft 102 relative to the crankshaft. The angular position
of the rotor 114 relative to the stator 116 (and the housing 112)
can be changed by disengaging the mechanical lock and applying
pressurized fluid through the fluid supply lines 130. Selectively
applying pressurized fluid to the first fluid supply line 132 can
advance the angular position of the rotor 114 relative to the
housing 112 and selectively applying pressurized fluid to the
second fluid supply line 134 can retard the angular position of the
rotor 114 relative to the housing 112.
[0021] The housing 112 transmits the rotational energy received
from the crankshaft from the ring gear 142 to the planetary gear(s)
140. The planetary gears 140, by virtue of engaging the ring gear
142 and the sprocket gear 146, communicate the rotational energy
from the housing 112 to the sprocket gear 146 attached to the inner
camshaft 104. As the housing 112 rotates in response to the
rotation of the crankshaft, the electric motor 148 of the
electrically-actuated second camshaft phaser 110 rotates the sun
gear 138. Depending on whether the angular position or the timing
of the inner camshaft 104 will be advanced, retarded, or maintained
relative to the crankshaft, the angular velocity of the output
shaft of the electric motor 148 can be increased, decreased, or
maintained relative to the angular velocity at which the housing
112 is rotated by the endless loop. The ring gear 142 can have a
different number of gear teeth relative to the sprocket gear 146.
In one implementation, the difference in the number of gear teeth
can equal the number of planetary gears 140. For example, if the
gearbox includes three planetary gears 140, the sprocket gear 146
can have 3 fewer teeth than the ring gear 142. As a result, when
the output shaft of the electric motor 148 rotates at an increased
or decreased angular velocity relative to the housing 112, the
sprocket gear is angularly displaced relative to the ring gear 142.
The second camshaft phaser 110 can include a locking plate 150 that
is axially adjacent to the sprocket gear 146 such that the locking
plate 150 can selectively engage the sprocket 146 to prevent the
angular displacement of the sprocket gear 146 relative to the
housing 112. An example of an electrically-actuated camshaft
phasing device or camshaft phaser is described in U.S. Patent
Application Publication No. 2017/0248045 the entirety of which is
incorporated by reference.
[0022] Turning to FIG. 5, another implementation of a variable
camshaft timing system (VCT) 200 is shown. The VCT system 200
includes a first camshaft 202 and a second camshaft 204 that are
concentric to each other forming a concentric camshaft assembly 206
as well as a first camshaft phaser 208 and a second camshaft phaser
210. Both the first camshaft phaser 208 and the second camshaft
phaser 210 are electrically-actuated. A first camshaft sprocket 212
can be coupled with the first camshaft 202, (e.g., the inner
camshaft) and a second camshaft sprocket 214 can be coupled with
the second camshaft 204 (e.g., the outer camshaft). The first
camshaft sprocket 212 and the second camshaft sprocket 214 can be
concentric with each other and each include a plurality of
radially-inwardly facing gear teeth 216. The gear teeth 216 of the
first camshaft sprocket 212 are axially spaced from the gear teeth
216 of the second camshaft sprocket 214. The first camshaft phaser
208 and the second camshaft phaser 210 can be physically engaged by
a housing 218 such that the housing 218 mechanically links the
first camshaft phaser 208 with the second camshaft phaser 210. The
housing 218 comprises a ring gear 220 that can be positioned
axially between the first camshaft sprocket 212 and the second
camshaft sprocket 214. The housing 218 or ring gear 220 can include
one or more slots 222 through which a portion of the second
camshaft sprocket 214 extends through axially thereby positioning
the second camshaft sprocket 214 in between an electric motor and
the ring gear 220 along the axis of camshaft rotation. The slots
222 can be arcuate having a length that corresponds to a range of
authority of the outer camshaft 204, which can control the amount
of angular displacement of the second camshaft sprocket 214
relative to the crankshaft. An outer surface of the housing 218
includes a plurality of radially outwardly extending gear teeth 224
that can engage an endless loop, such as a chain or a belt, and
communicate rotational force of the crankshaft from a crankshaft
sprocket having radially-outwardly facing teeth.
[0023] The first camshaft phaser 208 includes a first sun gear 226
and a first set of planetary gears 228 and the second camshaft
phaser 210 includes a second sun gear 230 and a second set of
planetary gears 232, respectively. Each of the sun gears 226, 230
and planetary gears 228, 232 include a plurality of
radially-outwardly facing gear teeth. The first set of planetary
gears 228 engages the first sun gear 226, the first camshaft
sprocket 212 coupled with the inner camshaft 202, and the ring gear
220 coupled with the housing 218. The second set of planetary gears
232 engages the second sun gear 230, the second camshaft sprocket
214 coupled with the outer camshaft 204, and the ring gear 220
coupled with the housing 218. The number of gear teeth on the first
camshaft sprocket 212 can differ from the number of gear teeth on
the ring gear 220. And the number of gear teeth on the second
camshaft sprocket 214 can differ from the number of gear teeth on
the ring gear 220. As described above, the number of gear teeth can
differ by the number of planetary gears. For example, if three
planetary gears engage the first sun gear 226, the first camshaft
sprocket 212, and the ring gear 220, the first camshaft sprocket
212 can have three fewer gear teeth than the ring gear 220. The
plurality of radially-outwardly facing gear teeth 224 can use an
endless loop, such as a chain or a belt, to engage the teeth of a
crankshaft sprocket thereby transmitting the rotational force from
the crankshaft to the housing 218.
[0024] The first sun gear 226 and the second sun gear 230 can be
coupled with a dual output electric motor 234. The dual-output
electric motor 234 can have two rotors and two stators. The rotors
can provide rotational output through concentric output shafts 236.
A first rotor 238 can be coupled with an inner output shaft 240 and
a second rotor 242 can be coupled with an outer output shaft 244;
the inner output shaft 240 and the outer output shaft 244 are
concentric to each other. In this implementation, the inner output
shaft 240 is coupled with the first sun gear 226 and the outer
output shaft 244 is coupled with the second sun gear 230. An
electric motor control unit can control the first rotor 238
independent from the control of the second rotor 240. A power
source can be electrically linked to a first stator 246 and a
second stator 248 through a first switch and a second switch,
respectively. The microprocessor can selectively open and close the
first and second switches as well and increase and decrease the
amount of current supplied to the first stator 246 and the second
stator 248.
[0025] As the crankshaft rotates as part of engine operation and
the crankshaft sprocket communicates the rotational force of the
crankshaft to the housing 218 via the endless loop, the housing 218
rotates imparting the rotation to the inner camshaft 202 and the
outer camshaft 204. The dual-output electric motor 234 can rotate
the inner output shaft 240 and outer output shaft 244 to rotate the
first sun gear 226 and the second sun gear 230, respectively. The
angular position of the inner camshaft 202 can be changed relative
to the crankshaft and the angular position of the outer camshaft
204 can be changed relative to the crankshaft, independent of the
angular position of the inner camshaft 202. When the dual-output
electric motor 234 rotates the inner output shaft 240 and the outer
output shaft 244 at the same angular velocity as the housing 218
and ring gear 220, the inner camshaft 202 and the outer camshaft
204 can maintain their existing angular position relative to the
crankshaft. The dual-output electric motor 234 can change the
angular position of the inner camshaft 202 relative to the
crankshaft, the outer camshaft 204 relative to the crankshaft, or
both. The microprocessor can direct the dual-output electric motor
234 to increase or decrease the angular velocity of the inner
output shaft 240 while maintaining the angular velocity of the
outer output shaft 244. An increase or decrease in the angular
velocity of the first sun gear 226 attached to the inner output
shaft 240 relative to the angular velocity of the ring gear 220
rotates the first set of planetary gears 228 thereby displacing the
first camshaft sprocket 212 relative to the ring gear 220 and
changes the angular position of the first camshaft sprocket 212 and
inner camshaft 202 relative to the crankshaft. An increase or
decrease in the angular velocity of the second sun gear 230
attached to the outer output shaft 244 relative to the angular
velocity of the ring gear 220 rotates the second set of planetary
gears 232 thereby displacing the second camshaft sprocket 214
relative to the ring gear 220 and changes the angular position of
the second camshaft sprocket 214 and outer camshaft 204 relative to
the crankshaft. The increase or decrease in the angular velocity of
the inner output shaft 240 can be carried out independently from
increases or decreases in the angular velocity of the outer output
shaft 244.
[0026] FIG. 6 depicts another implementation of a variable camshaft
timing system (VCT) 300. The VCT system 300 includes a first
camshaft 302 and a second camshaft 304 that are concentric to each
other forming a concentric camshaft assembly 306 as well as a first
camshaft phaser 308 and a second camshaft phaser 310. Both the
first camshaft phaser 308 and the second camshaft phaser 310 are
electrically-actuated. A first camshaft sprocket 312 can be coupled
with the first camshaft 302, (e.g., the inner camshaft) and a
second camshaft sprocket 314 can be coupled with the second
camshaft 304 (e.g., the outer camshaft). The first camshaft
sprocket 312 and the second camshaft sprocket 314 are concentric
with each other and each include a plurality of radially-inwardly
facing gear teeth 316. The gear teeth 316 of the first camshaft
sprocket 312 are axially spaced from the gear teeth 316 of the
second camshaft sprocket 314. The first camshaft phaser 308 and the
second camshaft phaser 310 can be physically engaged by a housing
318 such that the housing can mechanically link the first camshaft
phaser 308 with the second camshaft phaser 310 such that the
housing 318 constrains angular displacement of the first camshaft
phaser 308 relative to the second camshaft phaser 310. The housing
318 comprises a ring gear 320 that can be positioned axially
between the first camshaft sprocket 312 and the second camshaft
sprocket 314. The housing 318 or ring gear 320 can include one or
more slots 322 through which a portion of the second camshaft
sprocket 314 extends through axially thereby positioning the
radially-inwardly facing gears in between a dual output electric
motor 324 and the ring gear 320. The duel output electric motor
includes two motors, two stators, and concentric output shafts as
described above. The slots 322 can be arcuate having a length that
corresponds to a range of authority of the outer camshaft 304,
which can control the amount of angular displacement of the second
camshaft sprocket 314 relative to the crankshaft. An outer surface
of the housing includes a plurality of radially outwardly extending
gear teeth 326 that can engage an endless loop (not shown), such as
a chain or a belt, and communicate rotational force of the
crankshaft from a crankshaft sprocket having radially-outwardly
facing teeth.
[0027] The first camshaft phaser 308 includes a first eccentric
shaft 328 engaging a first compound planetary gear 330 and the
second camshaft phaser 310 includes a second eccentric shaft 332
engaging a second compound planetary gear 334. The first compound
planetary gear 330 includes inner camshaft sprocket teeth 336 and
first ring teeth 338. The second compound planetary gear 334
includes outer camshaft sprocket teeth 340 and second ring teeth
342. The first eccentric shaft 328 and the second eccentric shaft
332 can be coupled with the dual output electric motor 324 as
described above. The dual-output electric motor includes two rotors
and two stators. The rotors can provide rotational output through
concentric output shafts. A first rotor 344 can be coupled with an
inner output shaft 346 and a second rotor 348 can be coupled with
an outer output shaft 350; the inner output shaft 346 and the outer
output shaft 350 are concentric to each other. The inner output
shaft 346 can be coupled with the first eccentric shaft 328 and the
outer output shaft 350 can be coupled with the second eccentric
shaft 332. The first camshaft phaser 308 and the second camshaft
phaser 310 can be operated in a similar way as those shown in FIG.
5 as is described above.
[0028] Another implementation of a variable camshaft timing system
(VCT) 400 is shown in FIG. 7. The VCT system 400 includes a first
camshaft 402 and a second camshaft 404 that are concentric to each
other forming a concentric camshaft assembly 406 as well as a first
camshaft phaser 408 and a second camshaft phaser 410. The first
camshaft phaser 408 is coupled with the first camshaft 402 (e.g. an
outer camshaft) and a second camshaft phaser 410 is coupled with
the second camshaft 404 (e.g. an inner camshaft). The first
camshaft phaser 408 is implemented using a hydraulically-actuated
camshaft phaser and the second camshaft phaser 410 is implemented
using an electrically-actuated camshaft phaser. The first camshaft
phaser 408 and the second camshaft phaser 410 each include an input
and an output the can be angularly displaced relative to each
other.
[0029] The first camshaft phaser 408 can include a rotor 412 and a
stator 414. The rotor 412 can be the output of the first camshaft
phaser 402 that is coupled to a distal end of the first camshaft
402. The stator 414 can act as a housing that receives the rotor
412, as is described above with respect to FIG. 1, and be the input
of the first camshaft phaser 408. The housing or stator can include
an inner camshaft input sprocket 416 having a plurality of teeth
extending radially outwardly from an outer surface of the first
camshaft phaser 408 and be the input for the first camshaft phaser
408. The output of the first camshaft phaser 408 can be directly
coupled to a distal end of the inner camshaft 404.
[0030] The second camshaft phaser 410 can be attached to an idler
shaft 420 that is spaced apart from the concentric camshaft
assembly 406 such that the second camshaft phaser 410 rotates
around a different axis than the first camshaft phaser 408 and the
concentric camshaft assembly 406. The second camshaft phaser 410
can include an outer camshaft drive sprocket 422 and an inner
camshaft drive sprocket 424. The outer camshaft drive sprocket 422
can include an outer camshaft drive sprocket gear 426 that includes
a plurality of radially-outwardly facing gear teeth and an outer
camshaft drive ring gear 428 that includes a plurality of
radially-inwardly facing gear teeth. The inner camshaft drive
sprocket 424 can include an inner camshaft drive sprocket gear 430
that includes a plurality of radially-outwardly facing gear teeth
and an inner camshaft drive ring gear 432 that includes a plurality
of radially-inwardly facing gear teeth. The inner camshaft drive
sprocket 424 can also include a crankshaft drive sprocket gear 434
that includes a plurality of radially-outwardly facing gear teeth
that engage and receive rotational force from a crankshaft sprocket
(not shown) linked to a distal end of the crankshaft. A planetary
gearbox 436 including a plurality of planetary gears 438 can engage
both the inner camshaft drive ring gear 432 and the outer camshaft
drive ring gear 428. A sun gear 440 coupled with an output shaft
442 of an electric motor 444 can engage the planetary gears
438.
[0031] The crankshaft sprocket attached to the crankshaft engages
the crankshaft drive sprocket gear 434 and communicates rotational
force from the crankshaft to the inner camshaft drive sprocket 424.
The inner camshaft drive sprocket 424 engages the inner camshaft
input sprocket 416 and the rotational force from the crankshaft is
ultimately communicated from the inner camshaft drive sprocket 430
to the inner camshaft input sprocket 416. The rotor 412 of the
first camshaft phaser 408 can be angularly displaced relative to
the stator 414 (and the crankshaft) as is described above with
respect to hydraulically-actuated camshaft phasers. The outer
camshaft drive sprocket 422 is coupled with the crankshaft drive
sprocket gear 434, which can be implemented using a snap ring or
mechanical fasteners, such as bolts. An electric motor rotates the
output shaft 442 while the engine is operational and crankshaft and
the concentric camshaft assembly are rotating. The electric motor
444 turns the output shaft 442 and the sun gear 440 at the same
angular velocity as the ring gears 420,432 to maintain the angular
position of the outer camshaft 402 with respect to the crankshaft.
The angular position of the outer camshaft 402 can be varied
relative to the crankshaft by increasing or decreasing the angular
velocity of the output shaft 442 of the electric motor 444 thereby
increasing or decreasing the angular velocity of the sun gear 440.
The increase or decrease in the angular velocity of the sun gear
440 rotates the planetary gears 438 relative to the inner camshaft
drive ring gear 432 and the outer camshaft drive ring gear 428. The
inner camshaft drive ring gear 432 and the outer camshaft drive
ring gear 428 can each have a different number of gear teeth. As
described above, one of the inner camshaft drive ring gear 432 or
the outer camshaft drive ring gear 428 can have three fewer gear
teeth than the other ring gear such that rotating the sun gear 440
and planetary gears 438 relative to the inner camshaft drive ring
gear 432 and the outer camshaft drive ring gear 428 can displace
the inner camshaft drive ring gear 432 relative to the outer
camshaft drive ring gear 428 thereby changing the angular position
of the outer camshaft 402 relative to the crankshaft.
[0032] FIG. 8 depicts another implementation in which a first
camshaft phaser 108 is implemented using a hydraulically-actuated
camshaft phaser and a second camshaft phaser 108' is implemented
using a hydraulically-actuated camshaft phaser. The first camshaft
phaser 108 includes an input and an output. The input of the first
camshaft phaser 108 is received by a housing 112 and the output is
coupled with the first camshaft (e.g. the outer camshaft). The
input of the second camshaft phaser 110 is also received via the
housing 112 and the output is coupled with the second camshaft
(e.g. the inner camshaft 104). It should be appreciated that, in
other implementations, the output of a first camshaft phaser can be
coupled with an inner camshaft and the output of a second camshaft
phaser can be coupled with an outer camshaft. The second camshaft
phaser 108' includes an input and an output. The input of the
second camshaft phaser 108' is received by a housing 112' and the
output is coupled with the second camshaft (e.g. the inner
camshaft). The second camshaft phaser 108' includes a rotor 114',
and a stator 116' that is included in a portion of the housing
112'. The housing 112' can include an inner plate 113' and an outer
plate 115' that axially constrain the rotor 114' and at least
partially define one or more fluid chambers used with the rotor
114'.
[0033] It is to be understood that the foregoing is a description
of one or more embodiments of the invention. The invention is not
limited to the particular embodiment(s) disclosed herein, but
rather is defined solely by the claims below. Furthermore, the
statements contained in the foregoing description relate to
particular embodiments and are not to be construed as limitations
on the scope of the invention or on the definition of terms used in
the claims, except where a term or phrase is expressly defined
above. Various other embodiments and various changes and
modifications to the disclosed embodiment(s) will become apparent
to those skilled in the art. All such other embodiments, changes,
and modifications are intended to come within the scope of the
appended claims.
[0034] As used in this specification and claims, the terms "e.g.,"
"for example," "for instance," "such as," and "like," and the verbs
"comprising," "having," "including," and their other verb forms,
when used in conjunction with a listing of one or more components
or other items, are each to be construed as open-ended, meaning
that the listing is not to be considered as excluding other,
additional components or items. Other terms are to be construed
using their broadest reasonable meaning unless they are used in a
context that requires a different interpretation.
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