U.S. patent application number 16/250591 was filed with the patent office on 2020-07-23 for sliding camshaft assembly.
The applicant listed for this patent is GM Global Technology Operations LLC. Invention is credited to Domenic Certo, Bradley R. Kaan, Joseph J. Moon, Hong Wai Nguyen.
Application Number | 20200232348 16/250591 |
Document ID | / |
Family ID | 71402953 |
Filed Date | 2020-07-23 |
United States Patent
Application |
20200232348 |
Kind Code |
A1 |
Nguyen; Hong Wai ; et
al. |
July 23, 2020 |
SLIDING CAMSHAFT ASSEMBLY
Abstract
A camshaft assembly includes an actuator and an axially moveable
structure mounted to a base shaft wherein the axially moveable
structure includes a plurality of lobe packs and a cam barrel. The
axially movable structure moves along the base shaft in the axial
direction along a longitudinal axis of the base shaft, but is
rotationally fixed to the base shaft. The barrel cam includes an
inner wall and an outer wall which defines a control groove
therebetween. The control groove further defines first and second
regions wherein the first region includes a fixed narrow control
groove width and the second region includes a progressively
decreasing control groove width. The actuator shifts the axially
moveable structure relative to the base shaft between a first
position and a second position. A recess is defined in the outer
wall such that the recess is disposed adjacent to the first
region.
Inventors: |
Nguyen; Hong Wai; (Troy,
MI) ; Certo; Domenic; (Niagara Falls, CA) ;
Kaan; Bradley R.; (Oxford, MI) ; Moon; Joseph J.;
(BEVERLY HILLS, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM Global Technology Operations LLC |
Detroit |
MI |
US |
|
|
Family ID: |
71402953 |
Appl. No.: |
16/250591 |
Filed: |
January 17, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01L 2013/0078 20130101;
F01L 2013/0052 20130101; F01L 13/0036 20130101; F01L 2001/0471
20130101; F01L 1/047 20130101 |
International
Class: |
F01L 1/047 20060101
F01L001/047; F01L 13/00 20060101 F01L013/00 |
Claims
1. A camshaft assembly comprising: a base shaft extending along a
longitudinal axis; an axially movable structure mounted on the base
shaft and being axially movable relative to the base shaft between
a first position and a second position via an actuator while also
being rotationally fixed to the base shaft, the axially movable
structure includes: a plurality of lobe packs, each of the
plurality of lobe packs including a plurality of cam lobes; and a
barrel cam having a control groove defined between an inner wall
and an outer wall of the barrel cam such that the control groove
further includes a first region having a fixed narrow groove width
between the inner and outer walls and a second region having an
enlarged groove width between the inner wall and the outer walls;
and a recess is defined in the outer wall of the barrel cam such
that the recess is disposed adjacent to the first region; wherein
the recess is defined in the first region of the barrel cam, and
wherein the fixed narrow groove and the enlarged groove are aligned
circumferentially around the longitudinal axis at an axial
position, such that the control groove does not circumferentially
overlap with itself.
2. The camshaft assembly of claim 1 further comprising a sensor
configured to align with the axially moveable structure along a
first sensor path when the axially moveable structure moves to the
first position, and the sensor is configured to align with the
axially moveable structure along a second sensor path when the
axially moveable structure moves to the second position.
3. The camshaft assembly as defined in claim 2 wherein the first
sensor path overlays the outer wall and the recess defined in the
outer wall.
4. The camshaft assembly as defined in claim 3 wherein the second
sensor path overlays the control groove and the outer wall.
5. The camshaft assembly of claim 4, further comprising a control
module in communication with the actuator and the sensor.
6. The camshaft assembly of claim 5, wherein each lobe pack in the
plurality of lobe packs includes a first cam lobe adjacent to a
second cam lobe.
7. The camshaft assembly of claim 6, wherein the first cam lobe is
configured to engage with an engine valve when the axially moveable
structure is in the first position.
8. The camshaft assembly of claim 7 wherein the recess and outer
wall are configured to communicate to an engine control module via
the sensor to detect the first position of the axially movable
structure when the recess and the outer wall are aligned with the
sensor in a first sensor path.
9. The camshaft assembly of claim 8 wherein the control groove and
the outer wall are configured to communicate to an engine control
module via the sensor to detect the second position of the axially
movable structure when control groove and the outer wall are
aligned with the sensor in a second sensor path.
10. An engine assembly, comprising: an internal combustion engine
including a first cylinder, a second cylinder, a first valve
operatively coupled to the first cylinder, and a second valve
operatively coupled to the second cylinder; an engine control
module; a camshaft assembly operatively coupled to the first and
second valves, wherein the camshaft assembly includes: a base shaft
extending along a longitudinal axis, the base shaft being
configured to rotate about the longitudinal axis; an axially
movable structure being axially movable between a first position
and a second position on the base shaft and being rotationally
fixed to the base shaft, wherein the axially movable structure
further includes; a barrel cam having a control groove defined
between an inner wall and an outer wall of the barrel cam, the
control groove defining a fixed narrow groove width throughout a
first region and an enlarged groove width which progressively
varies in at least a portion of a second region of the barrel cam,
wherein the fixed narrow groove and the enlarged groove are aligned
circumferentially around the longitudinal axis at an axial
position, such that the control groove does not circumferentially
overlap with itself; and an actuator configured to move the axially
movable structure between the first and second positions via the
control groove in the barrel cam according to an output signal from
the engine control module; and a sensor configured to send a first
set of data to the engine control module when the axial moveable
structure is a first position and configured to send a second set
of data to the engine control module when the axial moveable
structure is in the second position, wherein a recess is defined in
the outer wall of the barrel cam and is aligned with the sensor
when the axially moveable structure is in the first position.
11. The engine assembly of claim 10 wherein the enlarged groove
width of the second region is greater than the fixed narrow groove
width of the first region.
12. The engine assembly of claim 11, wherein the axially moveable
structure further includes a plurality of lobe packs which are
configured to rotate synchronously with the barrel cam when the
axially movable structure rotates together with the base shaft.
13. The engine assembly of claim 12, wherein the actuator includes
at least one pin configured to move between a retracted and
extended positions in response to the output signal from the engine
control module.
14. The engine assembly of claim 13, wherein each lobe pack in the
plurality of lobe packs includes a first cam lobe being adjacent to
a second cam lobe.
15. The engine assembly of claim 14 wherein the first cam lobe has
a first maximum lobe height, the second cam lobe has a second
maximum lobe height, and the first maximum lobe height is different
from the second maximum lobe height.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a sliding camshaft for a
vehicle engine.
BACKGROUND
[0002] In modern internal combustion engines, variable valve
drives, with which different valve strokes can be set at the gas
exchange valves of the internal combustion engine, are used to
optimize the charge movement in the combustion chamber. The axial
displacement of the cam causes a different valve stroke to be set
at the respective gas exchange valve. The traditional valve drive
includes a sliding cam which is mounted in a rotationally fixed but
axially displaceable fashion on a camshaft wherein the sliding cam
may further include a cam barrel with a plurality of grooves, and
in which in order to bring about axial displacement of the sliding
cam an actuator having a plurality of pins which can be activated
is provided. The cam barrel may have a first, right-handed groove
and a second, left-handed groove which are arranged one next to the
other on the circumference of the cam barrel and merge with a
common run-out groove. The pins of the actuator interact with the
grooves of the cam barrel.
[0003] In addition, a valve drive is already known in which the
grooves of the cam barrel are positioned one behind the other on
the circumference of the cam barrel, specifically a first groove
for axial displacement of the sliding cam in a first direction and
a second groove for axial displacement of the sliding cam in an
opposing second direction. In this valve drive, the actuator also
has a plurality of pins which can be activated in order to bring
about axial displacement of the sliding cam, specifically a first
pin for axial displacement of the sliding cam in the two directions
about a first axial segment and a second pin for axial displacement
of the sliding cam in the two directions about a second axial
segment.
[0004] For the engine control of an internal combustion engine
having such a valve drive which has at least one displaceable
sliding cam, it is necessary to have knowledge of the relative
position of the sliding cam on the camshaft and therefore of the
cam lobes relative to the gas exchange valve of the internal
combustion engine which is to be activated. Hitherto, it was
difficult to detect in a certain and reliable way the relative
position of the sliding cam on the camshaft and therefore the
relative position of the cam tracks with respect to the gas
exchange valve which is to be activated.
SUMMARY
[0005] In one embodiment of the present disclosure, a camshaft
assembly is provided wherein the camshaft assembly includes an
actuator and an axially moveable structure mounted to a base shaft
wherein the axially moveable structure includes a plurality of lobe
packs and a cam barrel. The axially movable structure moves along
the base shaft in the axial direction along a longitudinal axis of
the base shaft, but is rotationally fixed to the base shaft. The
barrel cam includes an inner wall and an outer wall which defines a
control groove therebetween. The control groove further includes
first and second regions wherein the second region defines a fixed
narrow control groove width and the first region includes a
progressively changing control groove width. The actuator shifts
the axially moveable structure relative to the base shaft between a
first position and a second position. A recess is defined in the
outer wall of the barrel such that the recess is disposed adjacent
to the second region of the control groove.
[0006] The camshaft assembly may further include a sensor
configured to align with the axially moveable structure along a
first sensor path when the axially moveable structure moves to the
first position. The aforementioned sensor may also be configured to
align with the axially moveable structure along a second sensor
path when the axially moveable structure moves to the second
position. The first sensor path overlays the outer wall and the
recess defined in the outer wall. The second sensor path overlays
the control groove and the outer wall. However, it is understood
that the recess is disposed outside of the second sensor path.
Thus, the aforementioned camshaft assembly of the present
disclosure may also include an engine control module in
communication with the actuator and the sensor.
[0007] The recess and outer wall may be configured to communicate
to an engine control module via a sensor to detect/confirm the
first position of the axially movable structure when the recess and
the outer wall are aligned with the sensor in a first sensor path.
The sensor is configured to transmit feedback signals (in the form
of a first set of data) to the engine control module according to
the structure of the barrel cam along the first sensor path. More
specifically, the recess and outer wall are configured to
communicate with an engine control module via a sensor to
detect/confirm the first position of the axially movable structure
when the recess and the outer wall are aligned with the sensor in a
first sensor path.
[0008] Similarly, the control groove and the outer wall may also be
configured to communicate to an engine control module via the
sensor to detect/confirm the second position of the axially movable
structure when control groove and the outer wall are aligned with
the sensor in a second sensor path. The sensor is configured to
transmit feedback signals (in the form of a second set of data) to
the engine control module according to the structure of the barrel
cam along the second sensor path.
[0009] Each lobe pack in the plurality of lobe packs includes a
first cam lobe adjacent to a second cam lobe in the axial
direction. The first cam lobe is configured to engage with the
engine valve when the axially moveable structure is in the first
position. Similarly, the second cam lobe is configured to engage
with the engine valve when the axially moveable structure is in the
second position.
[0010] In yet another embodiment of the present disclosure, an
engine assembly includes an engine control module, an internal
combustion engine, a camshaft assembly, an actuator and a sensor.
The internal combustion engine includes a first cylinder, a second
cylinder, a first valve operatively coupled to the first cylinder,
and a second valve operatively coupled to the second cylinder. The
camshaft assembly may be coupled to the first and second valves of
the internal combustion engine. The camshaft assembly further
includes a base shaft and an axially moveable structure mounted on
the base shaft. The base shaft may extend along a longitudinal axis
and is configured to rotate about the longitudinal axis. The
axially moveable structure is configured to move between a first
position and a second position on the base shaft yet the axially
moveable structure is rotationally fixed to the base shaft. The
aforementioned axially moveable structure includes a barrel cam
having a control groove defined between an inner wall and an outer
wall of the barrel cam. The control groove may define a fixed
narrow groove width throughout a second region and may define an
enlarged groove width which progressively varies in at least a
portion of a first region of the barrel cam.
[0011] The actuator is configured to move the axially movable
structure between the first and second positions via a pin of the
actuator in engagement with the control groove in the barrel
cam--according to an output signal from the engine control module.
The sensor is configured to send a first set of data (feedback
signal) to the engine control module when axial moveable structure
is in the first position. The sensor is also configured to send a
second set of data (feedback signal) to the engine control module
when the axial moveable structure is in the second position. It is
understood that a recess is defined in the outer wall of the barrel
cam and is aligned with the sensor when the axially moveable
structure is in the first position.
[0012] With respect to the aforementioned engine assembly, the
enlarged groove width of the first region may be greater than the
fixed narrow groove width of the second region. As indicated, the
actuator may include at least one pin configured to move between
the retracted and extended positions (where the pin engages with
the control groove) in response to the output signal from the
engine control module. Moreover, the axially moveable structure may
further include a plurality of lobe packs which are configured to
rotate synchronously with the barrel cam when the axially movable
structure rotates together with the base shaft. Each lobe pack in
the plurality of lobe packs includes a first cam lobe being
adjacent to a second cam lobe. The first cam lobe has a first
maximum lobe height, the second cam lobe has a second maximum lobe
height, and the first maximum lobe height is different from the
second maximum lobe height.
[0013] The present disclosure and its particular features and
advantages will become more apparent from the following detailed
description considered with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] These and other features and advantages of the present
disclosure will be apparent from the following detailed
description, best mode, claims, and accompanying drawings in
which:
[0015] FIG. 1A is a schematic diagram of a vehicle including an
engine assembly.
[0016] FIG. 1B is an illustration of a sliding camshaft cover with
position shifting actuators and position detection sensors.
[0017] FIG. 2A is an isometric view of a barrel cam for a first
embodiment camshaft assembly in a first position.
[0018] FIG. 2B is an isometric view of the barrel cam of FIG. 2A
for the first embodiment camshaft assembly in a second
position.
[0019] FIG. 2C is a schematic view of a camshaft assembly of the
engine assembly of FIGS. 2A-2B (as the camshaft assembly rotates
relative to an actuator pin) in accordance with an example,
non-limiting embodiment of the present disclosure.
[0020] FIG. 2D is a schematic view of a barrel cam for yet another
example camshaft assembly according to the present disclosure.
[0021] FIG. 3 is a schematic view of the example, non-limiting
camshaft assembly in FIG. 2A-2C wherein the camshaft assembly is in
a first position.
[0022] FIG. 4 is a schematic view of the example, non-limiting
camshaft assembly in FIG. 2A-2C wherein the camshaft assembly is in
a second position.
[0023] Like reference numerals refer to like parts throughout the
description of several views of the drawings.
DETAILED DESCRIPTION
[0024] Reference will now be made in detail to presently preferred
compositions, embodiments and methods of the present disclosure,
which constitute the best modes of practicing the present
disclosure presently known to the inventors. The figures are not
necessarily to scale. However, it is to be understood that the
disclosed embodiments are merely exemplary of the present
disclosure that may be embodied in various and alternative forms.
Therefore, specific details disclosed herein are not to be
interpreted as limiting, but merely as a representative basis for
any aspect of the present disclosure and/or as a representative
basis for teaching one skilled in the art to variously employ the
present disclosure.
[0025] Except in the examples, or where otherwise expressly
indicated, all numerical quantities in this description indicating
amounts of material or conditions of reaction and/or use are to be
understood as modified by the word "about" in describing the
broadest scope of the present disclosure. Practice within the
numerical limits stated is generally preferred. Also, unless
expressly stated to the contrary: percent, "parts of," and ratio
values are by weight; the description of a group or class of
materials as suitable or preferred for a given purpose in
connection with the present disclosure implies that mixtures of any
two or more of the members of the group or class are equally
suitable or preferred; the first definition of an acronym or other
abbreviation applies to all subsequent uses herein of the same
abbreviation and applies mutatis mutandis to normal grammatical
variations of the initially defined abbreviation; and, unless
expressly stated to the contrary, measurement of a property is
determined by the same technique as previously or later referenced
for the same property.
[0026] It is also to be understood that this present disclosure is
not limited to the specific embodiments and methods described
below, as specific components and/or conditions may, of course,
vary. Furthermore, the terminology used herein is used only for the
purpose of describing particular embodiments of the present
disclosure and is not intended to be limiting in any way.
[0027] It must also be noted that, as used in the specification and
the appended claims, the singular form "a," "an," and "the"
comprise plural referents unless the context clearly indicates
otherwise. For example, reference to a component in the singular is
intended to comprise a plurality of components.
[0028] The term "comprising" is synonymous with "including,"
"having," "containing," or "characterized by." These terms are
inclusive and open-ended and do not exclude additional, un-recited
elements or method steps.
[0029] The phrase "consisting of" excludes any element, step, or
ingredient not specified in the claim. The phrase "consisting
essentially of" limits the scope of a claim to the specified
materials or steps, plus those that do not materially affect the
basic and novel characteristic(s) of the claimed subject
matter.
[0030] The terms "comprising", "consisting of", and "consisting
essentially of" can be alternatively used. Where one of these three
terms is used, the presently disclosed and claimed subject matter
can include the use of either of the other two terms.
[0031] Throughout this application, where publications are
referenced, the disclosures of these publications in their
entireties are hereby incorporated by reference into this
application to more fully describe the state of the art to which
this present disclosure pertains.
[0032] The following detailed description is merely exemplary in
nature and is not intended to limit the present disclosure or the
application and uses of the present disclosure. Furthermore, there
is no intention to be bound by any theory presented in the
preceding background or the following detailed description.
[0033] Referring to the drawings, wherein like reference numbers
correspond to like or similar components throughout the several
figures, FIG. 1A schematically illustrates a vehicle 10 such as a
car, truck or motorcycle. The vehicle 10 includes an engine
assembly 12. The engine assembly 12 includes an internal combustion
engine 14 and a control module 16, such an engine control module
(ECU), in electronic communication with the internal combustion
engine 14. The terms "control module," "module," "control,"
"controller," "control unit," "processor" and similar terms mean
any one or various combinations of one or more of Application
Specific Integrated Circuit(s) (ASIC), electronic circuit(s),
central processing unit(s) (preferably microprocessor(s)) and
associated memory and storage (read only, programmable read only,
random access, hard drive, etc.) executing one or more software or
firmware programs or routines, combinational logic circuit(s),
sequential logic circuit(s), input/output circuit(s) and devices,
appropriate signal conditioning and buffer circuitry, and other
components to provide the described functionality. "Software,"
"firmware," "programs," "instructions," "routines," "code,"
"algorithms" and similar terms mean any controller executable
instruction sets including calibrations and look-up tables. The
control module 16 may have a set of control routines executed to
provide the desired functions. Routines are executed, such as by a
central processing unit, and are operable to monitor inputs from
sensing devices and other networked control modules, and execute
control and diagnostic routines to control operation of actuators.
Routines may be executed based on events or at regular
intervals.
[0034] The internal combustion engine 14 includes an engine block
18 defining a plurality of cylinders 20A, 20B, 20C, and 20D. In
other words, the engine block 18 includes a first cylinder 20A, a
second cylinder 20B, a third cylinder 20C, and a fourth cylinder
20D. Although FIG. 1A schematically illustrates four cylinders, the
internal combustion engine 14 may include more or fewer cylinders.
The cylinders 20A, 206, 20C, and 20D are spaced apart from each
other but may be substantially aligned along an engine axis E. Each
of the cylinders 20A, 20B, 20C, and 20D is configured, shaped and
sized to receive a piston (not shown). The pistons are configured
to reciprocate within the cylinders 20A, 20B, 20C, and 20D. Each
cylinder 20A, 20B, 20C, 20D defines a corresponding combustion
chamber 22A, 22B, 22C, 22D. During operation of the internal
combustion engine 14, an air/fuel mixture is combusted inside the
combustion chambers 22A, 22B, 22C, and 22D in order to drive the
pistons in a reciprocating manner. The reciprocating motion of the
pistons drives a crankshaft (not shown) operatively connected to
the wheels (not shown) of the vehicle 10. The rotation of the
crankshaft can cause the wheels to rotate, thereby propelling the
vehicle 10.
[0035] In order to propel the vehicle 10, an air/fuel mixture
should be introduced into the combustion chambers 22A, 22B, 22C,
and 22D. To do so, the internal combustion engine 14 includes a
plurality of intake ports 24 fluidly coupled to an intake manifold
(not shown). In the depicted embodiment, the internal combustion
engine 14 includes two intake ports 24 in fluid communication with
each combustion chamber 22A, 22B, 22C, and 22D. However, the
internal combustion engine 14 may include more or fewer intake
ports 24 per combustion chamber 22A, 22B, 22C, and 22D. The
internal combustion engine 14 includes at least one intake port 24
per cylinder 20A, 20B, 20C, 20D.
[0036] The internal combustion engine 14 further includes a
plurality of intake valves 26 configured to control the flow of
inlet charge through the intake ports 24. The number of intake
valves 26 corresponds to the number of intake ports 24. Each intake
valve 26 is at least partially disposed within a corresponding
intake port 24. In particular, each intake valve 26 is configured
to move along the corresponding intake port 24 between an open
position and a closed position. In the open position, the intake
valve 26 allows inlet charge to enter a corresponding combustion
chamber 22A, 22B, 22C, or 22D via the corresponding intake port 24.
Conversely, in the closed position, the intake valve 26 precludes
the inlet charge from entering the corresponding combustion chamber
22A, 22B, 22C, or 22D via the intake port 24.
[0037] As discussed above, the internal combustion engine 14 can
combust the air/fuel mixture once the air/fuel mixture enters the
combustion chamber 22A, 22B, 22C, or 22D. For example, the internal
combustion engine 14 can combust the air/fuel mixture in the
combustion chamber 22A, 22B, 22C, or 22D using an ignition system
(not shown). This combustion generates exhaust gases. To expel
these exhaust gases, the internal combustion engine 14 defines a
plurality of exhaust ports 28. The exhaust ports 28 are in fluid
communication with the combustion chambers 22A, 22B, 22C, or 22D.
In the depicted embodiment, two exhaust ports 28 are in fluid
communication with each combustion chamber 22A, 22B, 22C, or 22D.
However, more or fewer exhaust ports 28 may be fluidly coupled to
each combustion chamber 22A, 226, 22C, or 22D. The internal
combustion engine 14 includes at least one exhaust port 28 per
cylinder 20A, 20B, 20C, or 20D.
[0038] The internal combustion engine 14 further includes a
plurality of exhaust valves 30 in fluid communication with the
combustion chambers 22A, 22B, 22C, or 22D. Each exhaust valve 30 is
at least partially disposed within a corresponding exhaust port 28.
In particular, each exhaust valve 30 is configured to move along
the corresponding exhaust port 28 between an open position and a
closed position. In the open position, the exhaust valve 30 allows
the exhaust gases to escape the corresponding combustion chamber
22A, 228, 22C, or 22D via the corresponding exhaust port 28. The
vehicle 10 may include an exhaust system (not shown) configured to
receive and treat exhaust gases from the internal combustion engine
14. In the closed position, the exhaust valve 30 precludes the
exhaust gases from exiting the corresponding combustion chamber
22A, 22B, 22C, or 22D via the corresponding exhaust port 28.
[0039] As discussed in detail below, intake valve 26 and exhaust
valve 30 (FIG. 1A) can also be generally referred to as engine
valves 66 (FIGS. 3-4) or simply valves. Each valve 66 (FIGS. 3-4)
is operatively coupled or associated with a cylinder 20A, 20B, 20C,
or 20D. Accordingly, the valves 66 (FIGS. 3-4) are configured to
control fluid flow (i.e., air/fuel mixture for intake valves 26 and
exhaust gas for exhaust valve 30) to the corresponding cylinder
20A, 20B, 20C, or 20D.
[0040] With further reference to FIG. 1A, the engine assembly 12
further includes a valvetrain system 32 configured to control the
operation of the intake valves 26 and exhaust valves 30.
Specifically, the valvetrain system 32 can move the intake valves
26 and exhaust valves 30 between the open and closed positions
based, at least in part, on the operating conditions of the
internal combustion engine 14 (e.g., engine speed). The valvetrain
system 32 includes one or more camshaft assemblies 33 (see FIGS.
3-4) substantially parallel to the engine axis E. In the depicted
embodiment, the valvetrain system 32 includes two camshaft
assemblies 33. One camshaft assembly 33 is configured to control
the operation of the intake valves 26, and the other camshaft
assembly 33 can control the operation of the exhaust valves 30.
[0041] Referring now to FIG. 1B, an illustration of a sliding
camshaft cover 40 with position shifting actuators (34A-34D) and
position detection sensors 52 in accordance with aspects of the
exemplary embodiment is provided. The sliding camshaft cover 40
shrouds the intake 82 and exhaust 84 sliding camshafts as
protection from the outside environment containments and retain oil
splatter produced by the operation of the engine. The position
detection sensors 52 are disposed in the sliding camshaft cover 40
proximate to at least one position shifting slot such that the
position of at least one barrel cam 56, e.g., camshaft barrel (56),
can be detected by the position detection sensor(s) 52 as described
herein. The position detection sensors 52 may be of the type that
are used for position detection suitable for an engine environment
including, but not limited to, a Hall Effect sensor.
[0042] With reference back to FIG. 1A, in addition to the camshaft
assemblies 33, the valvetrain assembly 32 includes a plurality of
actuators 34A, 34B, such as solenoids, in communication with the
control module 16. The actuators 34A, 34B may be electronically
connected to the control module 16 and may therefore be in
electronic communication with the control module 16. The control
module 16 may be part of the valvetrain system 32. In the depicted
embodiment, the valvetrain system 32 includes first, second
actuators 34A, 34B. Actuators 34A and 34B are operatively
associated with the first and second cylinders 20A, 20B wherein
actuator 34A shifts the lobes in the forward direction and actuator
34B shifts the lobes back in the rearward direction. Similarly,
actuators 34C and 34D are operatively associated with the third and
fourth cylinders 20C, 20D wherein actuator 34C shifts the lobes two
steps in the forward direction and actuator 34D shifts the lobes
back in the rearward direction.
[0043] Referring now to FIGS. 3-4, a camshaft assembly 33 includes
an actuator 34A, 34B (FIGS. 3-4) and an axially moveable structure
44 mounted to a base shaft 35 wherein the axially moveable
structure 44 includes a plurality of lobe packs 46 and a barrel cam
56. The axially movable structure 44 moves along the base shaft 35
in the axial direction along a longitudinal axis x, 37 of the base
shaft 35, but is rotationally fixed to the base shaft 35. The
barrel cam 56 includes an inner wall 94 and an outer wall 90 which
defines a control groove 60 therebetween. The control groove 60
further includes first and second regions wherein the second region
69 defines a fixed narrow control groove width 72 and the first
region 67 includes a progressively changing control groove width
70. The actuator 34A, 34B (FIGS. 3-4) shifts the axially moveable
structure 44 relative to the base shaft 35 between a first position
75 and a second position 77. A recess 92 is defined in the outer
wall 90 of the barrel cam 56 such that the recess 92 is disposed
adjacent to the second region 69 of the control groove 60 (FIGS.
2A-2C).
[0044] The camshaft assembly 33 may further include a sensor 52
configured to align with the axially moveable structure 44 along a
first sensor path 88 (FIG. 2A) when the axially moveable structure
44 moves to the first position 75 (FIG. 3). The aforementioned
sensor 52 may also be configured to align with the axially moveable
structure 44 along a second sensor path 86 (FIG. 28) when the
axially moveable structure 44 moves to the second position 77 (FIG.
4). As shown in FIG. 2A, the first sensor path 88 overlays the
outer wall 90 and the recess 92 defined in the outer wall 90. The
second sensor path 86 overlays the control groove 60 and the outer
wall 90. (see FIG. 2B). However, it is understood that the recess
92 is disposed outside of the second sensor path 86.
[0045] The engine control module 16 of FIG. 1A is in communication
with the actuator 34A, 34B (FIGS. 3-4) and the sensor 52. However,
the engine control module 16 is also in communication with the
recess 92 and outer wall 90 via a sensor 52 to detect/confirm the
first position 75 of the axially movable structure when the axial
moveable structure is in the first position 75 (FIG. 3). In the
arrangement shown in FIG. 3, the recess 92 and the outer wall 90
are aligned with the sensor 52 in a first sensor path 88 (see FIG.
2A). The sensor 52 is configured transmit feedback signals 79 (in
the form of a first set of data 81) to the engine control module 16
according to the structure of the barrel cam 56 along the first
sensor path 88. More specifically, the recess 92 and outer wall 90
are configured to communicate with an engine control module 16 via
a sensor 52 to detect/confirm the first position 75 of the axially
movable structure 44 when the recess 92 and the outer wall 90 are
aligned with the sensor 52 in a first sensor path 88.
[0046] Similarly, the control groove 60 and the outer wall 90 may
also be configured to communicate to the engine control module 16
via the sensor 52 to detect/confirm the second position 77 of the
axially movable structure 44 when control groove 60 and the outer
wall 90 are aligned with the sensor 52 in a second sensor path 86.
(See FIGS. 2B, 4). The sensor 52 is configured to transmit feedback
signals 79 (in the form of a second set of data 83) to the engine
control module 16 according to the structure of the barrel cam 56
along the second sensor path 86.
[0047] As shown in FIGS. 3-4, each lobe pack 46 in the plurality of
lobe packs 46 includes a first cam lobe 54B adjacent to a second
cam lobe 54A in the axial direction X, 37. The first cam lobe 54B
is configured to engage with the engine valve 66 when the axially
moveable structure 44 is in the first position 75. Similarly, the
second cam lobe 54A is configured to engage with the engine valve
66 when the axially moveable structure 44 is in the second position
77. The first cam lobe 54B has a first maximum lobe height 78 (see
FIG. 4), the second cam lobe 54A has a second maximum lobe height
76 (see FIG. 4) wherein the first maximum lobe height 78 is
different from the second maximum lobe height 76.
[0048] In yet another embodiment of the present disclosure shown in
FIG. 1A, an engine assembly 12 includes an engine control module
16, an internal combustion engine 14, a camshaft assembly 33, an
actuator 34A, 34B and a sensor 52. The internal combustion engine
14 includes a first cylinder 20A, a second cylinder 20B, a first
valve 66 operatively coupled to the first cylinder 20A, and a
second valve 66 operatively coupled to the second cylinder 20B. The
camshaft assembly 33 may be coupled to the first and second valves
66 of the internal combustion engine 14. The camshaft assembly 33
further includes a base shaft 35 and an axially moveable structure
44 mounted on the base shaft 35. The base shaft 35 may extend along
a longitudinal axis x, 37 and is configured to rotate about the
longitudinal axis x, 37. The axially moveable structure 44 is
configured to move between a first position 75 and a second
position 77 on the base shaft 35 yet the axially moveable structure
44 is rotationally fixed to the base shaft 35. The aforementioned
axially moveable structure 44 includes a barrel cam 56 having a
control groove 60 defined between an inner wall 94 and an outer
wall 90 of the barrel cam 56. The control groove 60 may define a
fixed narrow groove width 72 throughout a second region 69 and an
enlarged groove width 70 which progressively varies in at least a
portion of a first region 67 of the barrel cam 56.
[0049] With reference to FIGS. 3-4, the actuator 34A, 34B is
configured to move the axially movable structure 44 between the
first and second positions 75, 77 when a pin 64A, 64B of the
actuator is in engagement with the control groove 60 in the barrel
cam 56--according to an output signal 74 received from the engine
control module 16. The sensor 52 is configured to send a first set
of data 81 (feedback signal(s) 79) to the engine control module 16
when axial moveable structure is a first position 75. (see FIG. 3).
The sensor 52 is also configured to send a second set of data 83
(feedback signal(s) 79) to the engine control module 16 when the
axial moveable structure 44 is in the second position 77. (see FIG.
4) It is understood that a recess 92 is defined in the outer wall
90 of the barrel cam 56 and is aligned with the sensor 52 when the
axially moveable structure 44 is in the first position 75
regardless of a stack up tolerance 42.
[0050] With respect to the example barrel cam 56 of FIGS. 2A-2C and
FIGS. 3-4, the enlarged groove width 70 of the first region 67 may
be greater than the fixed narrow groove width 72 of the second
region 69. Regardless of the configuration of the control groove,
the plurality of lobe packs 46 are configured to rotate
synchronously with the barrel cam 56 when the axially movable
structure 44 rotates together with the base shaft 35. As shown in
FIG. 2D, another example control groove 60 is illustrated with
outer wall 90 and recess 92.
[0051] Specifically referring to the example shown in FIGS. 3-4,
the camshaft assembly 33 includes one or more (two in FIGS. 3-4)
axially movable structures 44 mounted on the base shaft 35. The
base shaft 35 extends along a longitudinal axis X, 37. The base
shaft 35 may include a first shaft end portion 36 and a second
shaft end portion 38 opposite the first shaft end portion 36. Each
axially movable structure 44 in the non-limiting example of FIGS.
3-4 includes lobe packs 46A-46D and cam barrel 56 integral to or
affixed to the lobe packs 46A-46D. The axially movable structures
44 are configured to move axially relative to the base shaft 35
along the longitudinal axis X, 37. However, the axially movable
structures 44 are rotationally fixed to the base shaft 35.
Consequently, the axially movable structures 44 rotate
synchronously with the base shaft 35. The base shaft 35 may include
a spline feature 48 for maintaining angular alignment of the
axially movable structures 44 to the base shaft 35 and also for
transmitting drive torque between the base shaft 35 and the axially
movable structures 44.
[0052] In the example shown in FIGS. 3-4, the axially movable
structures 44 are axially spaced apart from each other along the
longitudinal axis X, 37. However, described herein, a tolerance
stack up 41, 42 (see FIGS. 2A-2B) may occur in the camshaft
assembly as the axially moveable structures 44 and optional
journals are axially mounted on the base shaft 35. Regardless of
the tolerance stack up (or build variation) which may occur, the
sensor 52 for the camshaft assembly of the present disclosure will
be able to accurately detect the axial position of (the axially
moveable structures 44 on) the camshaft assembly as well as the
rotational position of (the axially moveable structures on)
camshaft assembly.
[0053] As shown in FIG. 3, the axially moveable structure 44 is
shown in the first position 75. In the first position 75, sensor 52
may be in communication with the barrel cam 56 of the present
disclosure wherein the sensor 52 may be aligned with the barrel cam
56 substantially along first sensor path 88 (shown in FIG. 2A)
wherein the first sensor path 88 overlays the outer wall 90 and the
recess in the outer wall 90 of the barrel cam 56--when the axially
moveable structure has been moved to the first position 75 shown in
FIG. 3. In this position, the sensor 52 is configured to provide
feedback signals 79 (see FIGS. 1B and 3) back to the control module
16 to identify the axial and rotational position of the camshaft
assembly. Specifically, the algorithm in the control module 16 may
require data (via feedback signals 79 from the sensor 52) which
identifies whether the axially moveable structure 44 is in the
first position 75 (shown in FIG. 3). In doing so, the feedback
signals 79 are compared against a model in the control module to
determine whether recess 92 and outer wall 90 are aligned with
sensor 52. When axially moveable structure 44 is in the first
position 75 (shown in FIG. 3), the cam barrel 56 should be aligned
with the sensor 52 substantially along the first sensor path 88
such that the recess 92 and outer wall 90 are aligned with the
sensor 52 (and the feedback signals 79 reflect that the recess 92
and outer wall 90 are communicating with and aligned with the
sensor 52). When the feedback signals 79 match the expected pattern
for the first position, the control module is able to accurately
confirm or determine that the axially moveable structure 44 is in
the first position 75 (FIG. 3) because (as shown in FIG. 2A) the
sensor 52 will be able to obtain consistent and reliable readings
regardless of whether the first sensor path 88 varies by the first
stack up tolerance 42 along longitudinal axis x, 37 in a positive
or negative direction given that the structure of the cam barrel 56
(outer wall 90 and recess 92) at the first sensor path 88 is
consistent (does not vary) in the regions immediately surrounding
the first sensor path 88.
[0054] Aside from determining or confirming the axial movement of
the axially moveable structure 44 when the structure 44 is in the
first position 75, the algorithm 25 in the control module 16 also
requires data (via feedback signals 79 from the sensor) to
determine/confirm the rotational position of the axially moveable
structure 44 and its corresponding lobe packs (rotational position
of the lobes which are engaging with the valve). Given that the
recess 92 and outer wall 90 are in a fixed angular position
relative to the cam lobes, the control module 16 (and its
associated algorithm) is also able to determine or confirm the
exact rotational position of the lobes 54B which are engaging with
the valves 66 when the axially moveable structure(s) 44 are in the
first position.
[0055] Each axially movable structure 44 may be a monolithic
structure. Accordingly, the lobe packs 46A, 46B, 46C, 46D and the
barrel cam 56 of the same axially movable structure 44 can
move/rotate simultaneously relative to the base shaft 35. Though
the drawings show that each axially movable structure 44 includes
four lobe packs 46A, 46B, 46C, 46D, it is understood that each
axially movable structure 44 may include more or fewer lobe
packs.
[0056] With specific reference to FIG. 4, the axially moveable
structure(s) are shown in the second position 77. When the
structure(s) 44 are in the second position 77, the control groove
60 and the outer wall 90 are configured to communicate with sensor
52 at second sensor path 86 (FIG. 2B). The example control groove
60 of FIGS. 3-4 may optionally include a central peninsula (shown
as element 47 in phantom) in first region 67 which creates two
paths 61 in control groove 60 in the barrel cam 56. Therefore, when
the axially moveable structure 44 is in the second position 77 as
shown in FIG. 4, sensor 52 may be in communication with the barrel
cam 56 of the present disclosure wherein the sensor 52 may be
aligned with the barrel cam 56 substantially along second sensor
path 86 (shown in FIG. 2B) wherein the second sensor path 86
overlays the control groove 60 and the outer wall 90 of the barrel
cam 56. In this position, the sensor 52 is configured to also
provide feedback signals 79 or second data set 83 (see FIGS. 1A and
4) back to the control module 16 to identify the axial and
rotational position of the camshaft assembly. Specifically, the
algorithm 25 in the control module 16 may require data (via
feedback signals 79 from the sensor 52) which identifies whether
the axially moveable structure 44 is in the second position 77
(shown in FIG. 4). In doing so, the feedback signals 79 (second
data set 83) are compared against a model 27 in the control module
16 to detect/confirm whether control groove 60 and outer wall 90
are aligned with sensor 52 (at second sensor path 86 in FIG.
2B).
[0057] When the feedback signals 79 (second set of data 83)
match/matches the expected pattern for the second position 77, the
control module 16 is able to accurately confirm or determine that
the axially moveable structure 44 is, in fact, in the second
position 77 (FIG. 4). It is understood that the second set of data
83 significantly differs from the first set of data 81 which is
obtained along the first sensor path 88. As a result of this
significant difference between the data readings at the first
sensor path 88 vs. the second sensor path 86, ambiguity regarding
the position of the axially moveable structure(s) in the camshaft
assembly is eliminated and a more accurate system is
provided--regardless of any stack up tolerances 41, 42 or
manufacturing variations 41, 42.
[0058] The algorithm in the control module 16 also may also require
data (via feedback signals 79 from the sensor) to determine/confirm
the rotational position of the axially moveable structure and its
corresponding lobe packs (rotational position of the lobes which
are engaging with the valve) when the axially moveable structure is
in the second position 77. The control module 16 (and its
associated algorithm) is also able to determine or confirm the
exact rotational position of the lobes 54B which are engaging with
the valves 66 when the axially moveable structure(s) 44 are in the
second position given that the control module knows: (1) the fixed
angular position of the control groove 60 and outer wall 90
relative to the cam lobe 54A (which engages with valve 66) in the
second position; and (2) the exact rotational position of the
control groove 60 and outer wall 90 (via the feedback signals 79
from sensor 52).
[0059] Therefore, in all embodiments of the present disclosure, the
cam barrel 56 includes an outer wall 90 wherein the outer wall 90
includes a groove wall surface 98 (forming part of control groove
60), an upper surface 100 and a lateral surface 102 (see FIGS.
2A-2C). The outer wall 90 is defined on the cam barrel 56 and
defines half of the control groove(s) 60 as shown in FIG. 2A-2C. As
indicated, the outer wall 90 further defines a recess 92 wherein
the recess 92 may optionally be disposed proximate to or adjacent
to a second region 69 of the control groove 60 which defines a
fixed, narrower groove width 72. (see FIGS. 2A-2C). It is
understood that the model 27 and algorithm 25 in the control module
16 are calibrated according to the unique chosen configuration of
the outer wall 90 and recess 92 relative to the first region 69 of
the control groove 60.
[0060] It is understood that second sensor path 86 may vary along
axis X, 37 as shown by tolerance stack up (element 42) in FIG. 2B
while first sensor path 88 may vary along axis X, 37 as shown by
tolerance stack up (element 41) in FIG. 2A. Furthermore, lack of
material (recess 90 in FIG. 2A) would only be detected by the
sensor 52 in the second region 69 when the sensor 52 is aligned in
the first sensor path 88 (in the first position 75). In contrast,
material (outer wall 90) would only be detected in the second
region 69 when the sensor 52 is aligned with the second sensor path
86 (second position 77). Again, due to the significant differences
between the feedback signals 79 of the first and second sensor
paths 86, 88 in the example second region, the camshaft assembly 33
of the present disclosure significantly eliminates ambiguity when
determining the axial position of the structure 44 relative to the
base shaft 35--regardless of the stack up tolerances 41, 42.
[0061] The control module 16 and/or sensor is configured detect the
absence of the material (in the form of the enlarged control groove
width 70) along second sensor path 86 in (see FIG. 2B) when the
sensor 52 is passing over the second region 69. The signals 79 (see
FIG. 1A) from the sensors 52 are continuously transmitted from the
sensor 52 to the control module 16 (see FIG. 1A) so that the
algorithm 25 in the control module 16 can accurately determine the
axial and/or rotational position of the camshaft
assembly--regardless of tolerance stack up 41, 42.
[0062] With respect to the example actuators of FIGS. 3-4, the
actuators 34A, 34B are configured to move the axially moveable
structure between the first position (shown in FIG. 2A and FIG. 3)
and the second position (shown in FIG. 2B and FIG. 4). Each
actuator 34A, 34B includes an actuator body 62A, 62B, wherein the
first and second pins 64A, 64B are movably coupled to each actuator
body 62A, 62B. The first and second pins 64A, 64B of each actuator
34A, 34B are axially spaced apart from each other and can move
independently from each other. Specifically, each of the first and
second pins 64A, 64B can move relative to the corresponding
actuator body 62A, 62B between a retracted position 71 and an
extended position 73 in response to an input or command from the
control module 16 (FIG. 1A). In the retracted position 71, the
first or second pin 64A or 64B is not disposed in the control
groove 60. Conversely, in the extended position 73, the first or
second pin 64A or 64B can be at least partially disposed in the
control groove 60. Accordingly, the first and second pins 64A, 64B
can move toward and away from the control groove 60 of the barrel
cam 56 in response to an input or command from the control module
16 (FIG. 1A). Hence, the first and second pins 64A, 64B of each
actuator 34A, 34B can move relative to a corresponding barrel cam
56 in a direction substantially perpendicular to the longitudinal
axis X, 37. Therefore, when the axially moveable structure 44 is in
the second position 77 as shown in FIG. 4, the sensor 52 is aligned
with path 86 shown in FIG. 2B. Similarly, when the axially moveable
structure is in the first position 75 as shown in FIG. 3, the
sensor 52 is aligned with first sensor path 88 shown in FIG.
2A.
[0063] It is understood that the axially movable structure 44 is
axially movable relative to the base shaft 35 from a first position
75 (FIG. 3) to a second position 77 (FIG. 4) when the base shaft 35
rotates about the longitudinal axis 37 as the second pin 64B is in
the extended position 73. The second pin 64B is at least partially
disposed in the control groove 60, and the second pin 64B is
configured to ride along at least a portion 85 of a second side 80B
of the first region 67 in the control groove 60 before entering the
second region 69 of the control groove 60. Moreover, it is also
similarly understood that the axially movable structure 44 is
axially movable relative to the base shaft 35 from the second
position 77 (FIG. 4) to a first position 75 (FIG. 3) when the base
shaft 35 rotates about the longitudinal axis 37, the first pin 64A
is in the extended position 73 as the first pin 64A is at least
partially disposed in the control groove 60, and the first pin 64A
rides along at least a portion 85 of a first side 80A of the first
region 67 in the control groove 60 before entering the second
region 69 of the control groove 60. The enlarged width 70
(progressive width 70) progressively varies within the first region
67. Regardless of the changing enlarged width 70 (progressive width
70) of the control groove 60 in the first region 67, any enlarged
width 70 or progressive width 70 defined in the first region 67 is
greater than the narrow fixed width 72 which remains constant in
the second region 69.
[0064] As noted, each lobe pack 46A-46D in plurality of lobe pack
46A, 46B, 46C, 46D in the axially movable structure 44 includes a
plurality of cam lobes 54A, 54B. The barrel cam 56 in the axially
movable structure 44 defines a control groove 60 defined by at
least one path 61 around a circumference 63 of the barrel cam 56
such that the at least one path 61 is defined by a first region 67
and a second region 69. The actuator 34A, 34B including an actuator
body 62A, 62B together with first and second pins 64A, 64B which
are each movably coupled to the actuator body 62A, 62B such that
each of the first and second pins 64A, 64B is movable relative to
the actuator body 62A, 62B between a retracted position 71 and an
extended position 73. The first and second pins 64A, 64B are
configured to ride along at least one path 61 defined by the
control groove 60. However, the axially movable structure 44 is
axially movable relative to the base shaft 35 from a first position
(FIG. 3) 75 to a second position 77 (FIG. 4) when the base shaft 35
rotates about the longitudinal axis 37, and the second pin 64B is
in the extended position 73 wherein the second pin 64B is at least
partially disposed in the control groove 60. Under this
arrangement, the second pin 64B is configured to ride along at
least a portion 85 of a second side 80B of the first region 67 in
the control groove 60 before entering the second region 69 of the
control groove 60. Similarly, the axially movable structure 44 is
axially movable relative to the base shaft 35 from a second
position 77 (FIG. 4) to a first position 75 (FIG. 3) when the base
shaft 35 rotates about the longitudinal axis 37, and the first pin
64A is in the extended position 73 such that the first pin 64A is
at least partially disposed in the control groove 60. Under this
arrangement, the first pin 64A is configured to ride along at least
a portion 85 of a first side 80A of the first region 67 in the
control groove 60 before entering the second region 69 of the
control groove 60. As shown in FIG. 2A, it is understood that the
first region 67 of the control groove 60 defines an enlarged width
70 in the control groove 60 and the second region 69 of the control
groove 60 defines a narrow width 72 in the control groove 60
wherein the narrow width 72 is less than the enlarged width 70. The
enlarged width 70 progressively varies within the first region
67.
[0065] While at least one exemplary embodiment has been presented
in the foregoing detailed description, it should be appreciated
that a vast number of variations exist. It should also be
appreciated that the exemplary embodiment or exemplary embodiments
are only examples, and are not intended to limit the scope,
applicability, or configuration of the disclosure in any way.
Rather, the foregoing detailed description will provide those
skilled in the art with a convenient road map for implementing the
exemplary embodiment or exemplary embodiments. It should be
understood that various changes can be made in the function and
arrangement of elements without departing from the scope of the
disclosure as set forth in the appended claims and the legal
equivalents thereof.
* * * * *