U.S. patent application number 14/554400 was filed with the patent office on 2016-05-26 for camshaft phaser with position control valve.
The applicant listed for this patent is DELPHI TECHNOLOGIES, INC.. Invention is credited to KARL J. HALTINER, JR., THOMAS H. LICHTI.
Application Number | 20160146068 14/554400 |
Document ID | / |
Family ID | 54476840 |
Filed Date | 2016-05-26 |
United States Patent
Application |
20160146068 |
Kind Code |
A1 |
HALTINER, JR.; KARL J. ; et
al. |
May 26, 2016 |
CAMSHAFT PHASER WITH POSITION CONTROL VALVE
Abstract
A camshaft phaser includes an input member; an output member
defining an advance chamber and a retard chamber with the input
member; a valve spool coaxially disposed within the output member
such that the valve spool is rotatable relative to the output
member and the input member, the valve spool defining a supply
chamber and a vent chamber with the output member; an actuator
which rotates the valve spool in order to change the position of
the output member relative to the input member by supplying
pressurized oil from the supply chamber to one of the advance
chamber and the retard chamber and venting oil to the vent chamber
from the other of the supply chamber and the advance chamber; and a
check valve which allows oil to flow from the vent chamber to the
supply chamber and prevents oil from flowing from the supply
chamber to the vent chamber.
Inventors: |
HALTINER, JR.; KARL J.;
(FAIRPORT, NY) ; LICHTI; THOMAS H.; (VICTOR,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DELPHI TECHNOLOGIES, INC. |
TROY |
MI |
US |
|
|
Family ID: |
54476840 |
Appl. No.: |
14/554400 |
Filed: |
November 26, 2014 |
Current U.S.
Class: |
123/90.12 |
Current CPC
Class: |
F01L 1/3442 20130101;
F01L 2001/34426 20130101; F01L 2001/34433 20130101; F01L 2001/34423
20130101; F04C 2/3448 20130101; F01L 1/34409 20130101 |
International
Class: |
F01L 1/344 20060101
F01L001/344; F04C 2/344 20060101 F04C002/344 |
Claims
1. A camshaft phaser for use with an internal combustion engine for
controllably varying the phase relationship between a crankshaft
and a camshaft in said internal combustion engine, said camshaft
phaser comprising: an input member connectable to said crankshaft
of said internal combustion engine to provide a fixed ratio of
rotation between said input member and said crankshaft; an output
member connectable to said camshaft of said internal combustion
engine and defining an advance chamber and a retard chamber with
said input member; a valve spool coaxially disposed within said
output member such that said valve spool is rotatable relative to
said output member and said input member, said valve spool defining
a supply chamber and a vent chamber with said output member; an
actuator which rotates said valve spool in order to change the
position of said output member relative to said input member by 1)
supplying oil from said supply chamber to said advance chamber and
venting oil from said retard chamber to said vent chamber when
retarding the phase relationship of said camshaft relative to said
crankshaft is desired and 2) supplying oil from said supply chamber
to said retard chamber and venting oil from said advance chamber to
said vent chamber when advancing the phase relationship between
said camshaft relative to said crankshaft is desired; and a phasing
check valve which allows oil to flow from said vent chamber to said
supply chamber and prevents oil from flowing from said supply
chamber to said vent chamber.
2. A camshaft phaser as in claim 1 wherein: said vent chamber
receives pressurized oil from said advance chamber when advancing
the phase relationship of said camshaft relative to said
crankshaft; and said vent chamber receives pressurized oil from
said retard chamber when retarding the phase relationship of said
camshaft relative to said crankshaft.
3. A camshaft phaser as in claim 1 wherein: said input member is a
stator having a plurality of lobes; said output member is a rotor
coaxially disposed within said stator, said rotor having a
plurality of vanes interspersed with said plurality of lobes; said
advance chamber is one of a plurality of advance chambers defined
by said plurality of vanes and said plurality of lobes; and said
retard chamber is one of a plurality of retard chambers defined by
said plurality of vanes and said plurality of lobes.
4. A camshaft phaser as in claim 3 wherein said supply chamber is
one of a plurality of supply chambers defined with said rotor and
said vent chamber is one of a plurality of vent chambers defined
with said rotor such that said plurality of supply chambers are
arranged in an alternating pattern with said plurality of vent
chambers.
5. A camshaft phaser as in claim 4 wherein said phasing check valve
is one of a plurality of phasing check valves where said plurality
of phasing check valves allows oil to flow from said plurality of
vent chambers to said plurality of supply chambers and prevent oil
from flowing from said plurality of supply chambers to said
plurality of vent chambers.
6. A camshaft phaser as in claim 5 wherein said rotor includes a
rotor central hub from which said plurality of vanes extend
radially outward therefrom, said rotor central hub having a rotor
central through bore extending axially therethrough.
7. A camshaft phaser as in claim 6 wherein: said rotor central hub
defines an annular valve spool recess coaxially therein such that
said annular valve spool recess divides said rotor central hub into
a rotor central hub inner portion and a rotor central hub outer
portion; and said valve spool is rotatably located coaxially within
said annular valve spool recess.
8. A camshaft phaser as in claim 7 wherein: said valve spool
includes a spool central hub with a spool central through bore
extending coaxially therethrough; and said spool central through
bore is sized to mate with said rotor central hub inner portion in
a close sliding interface such that said valve spool is able to
freely rotate on said rotor central hub inner portion while
substantially preventing oil from passing between the interface of
said spool central through bore and said rotor central hub inner
portion.
9. A camshaft phaser as in claim 8 where a plurality valve spool
lands are circumferentially spaced and extend radially outward from
said spool central hub such that said plurality of supply chambers
and said plurality of vent chambers are separated by said plurality
of valve spool lands.
10. A camshaft phaser as in claim 9 wherein said plurality of valve
spool lands selectively prevent fluid communication between 1) said
plurality of supply chambers and said plurality of advance
chambers, 2) said plurality vent chambers and said plurality of
advance chambers, 3) said plurality of supply chambers and said
plurality of retard chambers, and 4) said plurality of vent
chambers and said plurality of retard chambers.
11. A camshaft phaser as in claim 8 wherein said camshaft phaser
further comprises: a back cover closing one axial end of said
stator; a front cover closing the other axial end of said stator
such that said plurality of advance chambers and said plurality of
retard chambers are defined axially between said back cover and
said front cover, said front cover having a front cover central
bore extending coaxially therethrough; wherein said valve spool is
captured axially between said annular valve spool recess and said
front cover.
12. A camshaft phaser as in claim 11 wherein: a reservoir is
defined between said valve spool and said front cover; and oil
communicated to said plurality of supply chambers from said
plurality of vent chambers passes through said reservoir.
13. A camshaft phaser as in claim 6 further comprising a camshaft
phaser attachment bolt extending coaxially through said rotor
central through bore for clamping said rotor to said camshaft,
wherein said valve spool radially surrounds said camshaft phaser
attachment bolt.
14. A camshaft phaser as in claim 4 wherein: a hold position of
said valve spool relative to said rotor blocks fluid communication
between said plurality of supply chambers and said plurality of
advance chambers and said plurality of retard chambers and also
blocks fluid communication between said plurality of vent chambers
and said plurality of advance chambers and said plurality of retard
chambers, thereby preventing rotation of said rotor relative to
said stator; clockwise rotation of said valve spool relative to
said stator causes said rotor to rotate clockwise relative to said
stator and clockwise relative to said valve spool by opening
passages between said plurality of supply chambers and said
plurality of advance chambers or said plurality of retard chambers
and by opening passages between said plurality of vent chambers and
1) said plurality of advance chambers if said plurality of supply
chambers are opened to said plurality of retard chambers and 2)
said plurality of retard chambers if said plurality of supply
chambers are opened to said plurality of advance chambers until
said rotor is in said hold position relative to said valve spool;
and counterclockwise rotation of said valve spool relative to said
stator causes said rotor to rotate counterclockwise relative to
said stator and counterclockwise relative to said valve spool by
opening passages between said plurality of supply chambers and the
other of said plurality of advance chambers said plurality of
retard chambers and by opening passages between said plurality of
vent chambers and 1) said plurality of advance chambers if said
plurality of supply chambers are opened to said plurality of retard
chambers and 2) said plurality of retard chambers if said plurality
of supply chambers are opened to said plurality of advance chambers
until said rotor is in said hold position relative to said valve
spool.
15. A camshaft phaser as in claim 5 wherein: a hold position of
said valve spool relative to said rotor blocks fluid communication
between said plurality of supply chambers and said plurality of
advance chambers and said plurality of retard chambers and also
blocks fluid communication between said plurality of vent chambers
and said plurality of advance chambers and said plurality of retard
chambers, thereby preventing rotation of said rotor relative to
said stator; clockwise rotation of said valve spool relative to
said stator causes passages to open between said plurality of
advance chambers and said plurality of retard chambers such that
said plurality of phasing check valves permit oil flow between said
plurality of advance chambers and said plurality of retard chambers
to cause said rotor to rotate clockwise relative to said stator and
clockwise relative to said valve spool and such that said plurality
of phasing check valves prevent oil flow between said plurality of
advance chambers and said plurality of retard chambers to prevent
counterclockwise rotation of said rotor relative to said stator;
and counterclockwise rotation of said valve spool relative to said
stator causes passages to open between said plurality of advance
chambers and said plurality of retard chambers such that said
plurality of phasing check valves permit oil flow between said
plurality of advance chambers and said plurality of retard chambers
to cause said rotor to rotate counterclockwise relative to said
stator and counterclockwise relative to said valve spool and such
that said plurality of phasing check valves prevent oil flow
between said plurality of advance chambers and said plurality of
retard chambers to prevent clockwise rotation of said rotor
relative to said stator.
16. A camshaft phaser as in claim 15 wherein: clockwise rotation of
said valve spool relative to said stator causes said rotor to
rotate clockwise relative to said stator and clockwise relative to
said valve spool until said rotor is in said hold position relative
to said valve spool; and counterclockwise rotation of said valve
spool relative to said stator causes said rotor to rotate
counterclockwise relative to said stator and counterclockwise
relative to said valve spool until said rotor is in said hold
position relative to said valve spool.
17. A camshaft phaser as in claim 1 wherein axial movement of said
valve spool relative to said output member is substantially
prevented.
18. A camshaft phaser for use with an internal combustion engine
for controllably varying the phase relationship between a
crankshaft and a camshaft in said internal combustion engine, said
camshaft phaser comprising: a stator having a plurality of lobes
and connectable to said crankshaft of said internal combustion
engine to provide a fixed ratio of rotation between said stator and
said crankshaft about an axis; a rotor coaxially disposed within
said stator, said rotor having a plurality of vanes interspersed
with said plurality of lobes defining a plurality of alternating
advance chambers and retard chambers; a valve spool coaxially
disposed within said rotor such that said valve spool is rotatable
relative to said rotor and said stator, said valve spool defining a
plurality of alternating supply chambers and vent chambers with
said rotor; an actuator which rotates said valve spool in order to
change the rotational position of said rotor relative to said
stator by 1) supplying pressurized oil from said plurality of
supply chambers to said plurality of advance chambers and venting
oil from said plurality of retard chambers to said plurality of
vent chambers when retarding the phase relationship of said
camshaft relative to said crankshaft is desired and 2) supplying
pressurized oil from said plurality of supply chambers to said
plurality of retard chambers and venting oil from said plurality of
advance chambers to said plurality of vent chambers when advancing
the phase relationship between said camshaft relative to said
crankshaft is desired; and a plurality of phasing check valves
which allow oil to flow from said plurality of vent chambers to
said plurality of supply chambers and prevent oil from flowing from
said plurality of supply chambers to said plurality of vent
chambers.
19. A camshaft phaser for use with an internal combustion engine
for controllably varying the phase relationship between a
crankshaft and a camshaft in said internal combustion engine, said
camshaft phaser comprising: a stator having a plurality of lobes
and connectable to said crankshaft of said internal combustion
engine to provide a fixed ratio of rotation between said stator and
said crankshaft about an axis; a rotor coaxially disposed within
said stator, said rotor having a plurality of vanes interspersed
with said plurality of lobes defining a plurality of alternating
advance chambers and retard chambers; a valve spool coaxially
disposed within said rotor such that said valve spool is rotatable
relative to said rotor and said stator, said valve spool defining a
plurality of alternating supply chambers and vent chambers with
said rotor; an actuator which rotates said valve spool in order to
change the rotational position of said rotor relative to said
stator by 1) supplying pressurized oil from said plurality of
supply chambers to said plurality of advance chambers and venting
oil from said plurality of retard chambers to said plurality of
vent chambers, as a result of torque reversals applied to said
camshaft, when retarding the phase relationship of said camshaft
relative to said crankshaft is desired and 2) supplying pressurized
oil from said plurality of supply chambers to said plurality of
retard chambers and venting oil from said plurality of advance
chambers to said plurality of vent chambers, as a result of torque
reversals applied to said camshaft, when advancing the phase
relationship between said camshaft relative to said crankshaft is
desired; and a plurality of phasing check valves which allow oil to
flow from said plurality of vent chambers to said plurality of
supply chambers and prevent oil from flowing from said plurality of
supply chambers to said plurality of vent chambers.
Description
TECHNICAL FIELD OF INVENTION
[0001] The present invention relates to a camshaft phaser for
varying the phase relationship between a crankshaft and a camshaft
in an internal combustion engine; more particularly to such a
camshaft phaser which is a vane-type camshaft phaser; even more
particularly to a vane-type camshaft phaser which includes a
control valve in which the position of the control valve determines
the phase relationship between the crankshaft and the camshaft; and
still even more particularly to such a camshaft phaser which uses
torque reversals of the camshaft to actuate the camshaft
phaser.
BACKGROUND OF INVENTION
[0002] A typical vane-type camshaft phaser for changing the phase
relationship between a crankshaft and a camshaft of an internal
combustion engine generally comprises a plurality of
outwardly-extending vanes on a rotor interspersed with a plurality
of inwardly-extending lobes on a stator, forming alternating
advance and retard chambers between the vanes and lobes. Engine oil
is selectively supplied to one of the advance and retard chambers
and vacated from the other of the advance chambers and retard
chambers by a phasing oil control valve in order to rotate the
rotor within the stator and thereby change the phase relationship
between the camshaft and the crankshaft. One such camshaft phaser
is described in U.S. Pat. No. 8,534,246 to Lichti et al., the
disclosure of which is incorporated herein by reference in its
entirety and hereinafter referred to as Lichti et al. As is typical
for phasing oil control valves, the phasing oil control valve of
Lichti et al. operates on the principle of direction control, i.e.
the position of the oil control valve determines the direction of
rotation of the rotor relative to the stator. More specifically,
when a desired phase relationship between the camshaft and the
crankshaft is determined, the desired phase relationship is
compared to the actual phase relationship as determined from the
outputs of a camshaft position sensor and a crankshaft position
sensor. If the actual phase relationship, does not match the
desired phase relationship, the oil control valve is actuated to
either 1) an advance position to supply oil to the retard chambers
and vent oil from the advance chambers or 2) a retard position to
supply oil to the advance chambers and vent oil from the retard
chambers until the actual phase relationship matches the desired
phase relationship. When the actual phase relationship matches the
desired phase relationship, the oil control valve is positioned to
hydraulically lock the rotor relative to the stator. However,
leakage from the advance chambers and the retard chambers or
leakage from the oil control valve may cause the phase relationship
to drift over time. When the drift in phase relationship is
detected by comparing the actual phase relationship to the desired
phase relationship, the oil control valve must again be actuated to
either the advance position or the retard position in order to
correct for the drift, then the oil control valve is again
positioned to hydraulically lock the rotor relative to the stator
after the correction has been made. Consequently, the position of
the rotor relative to the stator is not self-correcting and relies
upon actuation of the phasing oil control valve to correct for the
drift.
[0003] U.S. Pat. No. 5,507,254 to Melchior, hereinafter referred to
as Melchior, teaches a camshaft phaser with a phasing oil control
valve which allows for self-correction of the rotor relative to the
stator as may be necessary due to leakage from the advance chamber
or from the retard chamber. Melchior also teaches that the valve
spool defines a first recess and a second recess separated by a rib
such that one of the recesses acts to supply oil to the advance
chamber when a retard in timing of the camshaft is desired while
the other recess acts to supply oil to the retard chamber when an
advance in the timing of the camshaft is desired. The recess that
does not act to supply oil when a change in phase is desired does
not act as a flow path. However, improvements are always sought in
any art.
[0004] What is needed is a camshaft phaser which minimizes or
eliminates one or more the shortcomings as set forth above.
SUMMARY OF THE INVENTION
[0005] Briefly described, a camshaft phaser is provided for use
with an internal combustion engine for controllably varying the
phase relationship between a crankshaft and a camshaft in the
internal combustion engine. The camshaft phaser includes an input
member connectable to the crankshaft of the internal combustion
engine to provide a fixed ratio of rotation between the input
member and the crankshaft; an output member connectable to the
camshaft of the internal combustion engine and defining an advance
chamber and a retard chamber with the input member; a valve spool
coaxially disposed within the output member such that the valve
spool is rotatable relative to the output member and the input
member, the valve spool defining a supply chamber and a vent
chamber with the output member; an actuator which rotates the valve
spool in order to change the position of the output member relative
to the input member by 1) supplying oil from the supply chamber to
the advance chamber and venting oil from the retard chamber to the
vent chamber when retarding the phase relationship of the camshaft
relative to the crankshaft is desired and 2) supplying oil from the
supply chamber to the retard chamber and venting oil from the
advance chamber to the vent chamber when advancing the phase
relationship between the camshaft relative to the crankshaft is
desired; and a phasing check valve which allows oil to flow from
the vent chamber to the supply chamber and prevents oil from
flowing from the supply chamber to the vent chamber.
[0006] Further features and advantages of the invention will appear
more clearly on a reading of the following detailed description of
the preferred embodiment of the invention, which is given by way of
non-limiting example only and with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0007] This invention will be further described with reference to
the accompanying drawings in which:
[0008] FIG. 1 is an exploded isometric view of a camshaft phaser in
accordance with the present invention;
[0009] FIG. 2 is an axial cross-section view of the camshaft phaser
of FIG. 1;
[0010] FIG. 3 is a radial cross-sectional view of the camshaft
phaser taken through section line 3-3 of FIG. 2 and showing a valve
spool of the camshaft phaser in a hold position which maintains a
rotational position of a rotor of the camshaft phaser relative to a
stator of the camshaft phaser;
[0011] FIG. 4 is a radial cross-sectional view of the camshaft
phaser taken through section line 4-4 of FIG. 2 and showing the
valve spool of the camshaft phaser in a hold position which
maintains a rotational position of the rotor relative to the
stator;
[0012] FIG. 5A is a radial cross-sectional view of the camshaft
phaser taken through section line 3-3 of FIG. 2 showing the valve
spool in a position which will result in a clockwise rotation of
the rotor relative to the stator;
[0013] FIG. 5B is a radial cross-sectional view of the camshaft
phaser taken through section line 4-4 of FIG. 2 showing the valve
spool in the position of FIG. 5A;
[0014] FIG. 5C is a radial cross-sectional view of the camshaft
phaser taken through section line 3-3 of FIG. 2 showing the rotor
after being rotated clockwise as a result of the position of the
valve spool as shown in FIG. 5A;
[0015] FIG. 5D is the axial cross-sectional view of FIG. 2 with
reference numbers removed in order to clearly shown the path of oil
flow as a result of the position of the valve spool as shown in
FIG. 5A;
[0016] FIG. 5E is the radial cross-sectional view of FIG. 5A with
reference numbers removed in order to clearly shown the path of oil
flow as a result of the position of the valve spool as shown in
FIG. 5A;
[0017] FIG. 5F is the radial cross-sectional view of FIG. 5B with
reference numbers removed in order to clearly shown the path of oil
flow as a result of the position of the valve spool as shown in
FIG. 5A;
[0018] FIG. 6A is a radial cross-sectional view of the camshaft
phaser taken through section line 3-3 of FIG. 2 showing the valve
spool in a position which will result in a counterclockwise
rotation of the rotor relative to the stator;
[0019] FIG. 6B is a radial cross-sectional view of the camshaft
phaser taken through section line 4-4 of FIG. 2 showing the valve
spool in the position of FIG. 6A;
[0020] FIG. 6C is a radial cross-sectional view of the camshaft
phaser taken through section line 3-3 of FIG. 2 showing the rotor
after being rotated clockwise as a result of the position of the
valve spool as shown in FIG. 6A;
[0021] FIG. 6D is the axial cross-sectional view of FIG. 2 with
reference numbers removed in order to clearly shown the path of oil
flow as a result of the position of the valve spool as shown in
FIG. 6A;
[0022] FIG. 6E is the radial cross-sectional view of FIG. 6A with
reference numbers removed in order to clearly shown the path of oil
flow as a result of the position of the valve spool as shown in
FIG. 6A; and
[0023] FIG. 6F is the radial cross-sectional view of FIG. 6B with
reference numbers removed in order to clearly shown the path of oil
flow as a result of the position of the valve spool as shown in
FIG. 6A.
DETAILED DESCRIPTION OF INVENTION
[0024] In accordance with a preferred embodiment of this invention
and referring to FIGS. 1-4, an internal combustion engine 10 is
shown which includes a camshaft phaser 12. Internal combustion
engine 10 also includes a camshaft 14 which is rotatable about a
camshaft axis 16 based on rotational input from a crankshaft and
chain (not shown) driven by a plurality of reciprocating pistons
(also not shown). As camshaft 14 is rotated, it imparts valve
lifting and closing motion to intake and/or exhaust valves (not
shown) as is well known in the internal combustion engine art.
Camshaft phaser 12 allows the timing or phase between the
crankshaft and camshaft 14 to be varied. In this way, opening and
closing of the intake and/or exhaust valves can be advanced or
retarded in order to achieve desired engine performance.
[0025] Camshaft phaser 12 generally includes a stator 18 which acts
as an input member, a rotor 20 disposed coaxially within stator 18
which acts as an output member, a back cover 22 closing off one
axial end of stator 18, a front cover 24 closing off the other
axial end of stator 18, a camshaft phaser attachment bolt 26 for
attaching camshaft phaser 12 to camshaft 14, and a valve spool 28.
The rotational position of valve spool 28 relative to stator 18
determines the rotational position of rotor 20 relative to stator
18, unlike typical valve spools which move axially to determine
only the direction the rotor will rotate relative to the stator.
The various elements of camshaft phaser 12 will be described in
greater detail in the paragraphs that follow.
[0026] Stator 18 is generally cylindrical and includes a plurality
of radial chambers 30 defined by a plurality of lobes 32 extending
radially inward. In the embodiment shown, there are three lobes 32
defining three radial chambers 30, however, it is to be understood
that a different number of lobes 32 may be provided to define
radial chambers 30 equal in quantity to the number of lobes 32.
[0027] Rotor 20 includes a rotor central hub 36 with a plurality of
vanes 38 extending radially outward therefrom and a rotor central
through bore 40 extending axially therethrough. The number of vanes
38 is equal to the number of radial chambers 30 provided in stator
18. Rotor 20 is coaxially disposed within stator 18 such that each
vane 38 divides each radial chamber 30 into advance chambers 42 and
retard chambers 44. The radial tips of lobes 32 are mateable with
rotor central hub 36 in order to separate radial chambers 30 from
each other. Each of the radial tips of vanes 38 may include one of
a plurality of wiper seals 46 to substantially seal adjacent
advance chambers 42 and retard chambers 44 from each other. While
not shown, each of the radial tips of lobes 32 may also include one
of a plurality of wiper seals 46.
[0028] Rotor central hub 36 defines an annular valve spool recess
48 which extends part way into rotor central hub 36 from the axial
end of rotor central hub 36 that is proximal to front cover 24. As
a result, rotor central hub 36 includes a rotor central hub inner
portion 50 that is annular in shape and bounded radially inward by
rotor central through bore 40 and bounded radially outward by
annular valve spool recess 48. Also as a result, rotor central hub
36 includes a rotor central hub outer portion 52 that is bounded
radially inward by annular valve spool recess 48 and is bounded
radially outward by the radially outward portion of rotor central
hub outer portion 52 from which lobes 32 extend radially outward.
Since annular valve spool recess 48 extends only part way into
rotor central hub 36, annular valve spool recess 48 defines an
annular valve spool recess bottom 54 which is annular in shape and
extends between rotor central hub inner portion 50 and rotor
central hub outer portion 52. As shown, annular valve spool recess
bottom 54 may be stepped, thereby defining a valve spool recess
shoulder 56 that is substantially perpendicular to camshaft axis
16.
[0029] Back cover 22 is sealingly secured, using cover bolts 60, to
the axial end of stator 18 that is proximal to camshaft 14.
Tightening of cover bolts 60 prevents relative rotation between
back cover 22 and stator 18. Back cover 22 includes a back cover
central bore 62 extending coaxially therethrough. The end of
camshaft 14 is received coaxially within back cover central bore 62
such that camshaft 14 is allowed to rotate relative to back cover
22. Back cover 22 may also include a sprocket 64 formed integrally
therewith or otherwise fixed thereto. Sprocket 64 is configured to
be driven by a chain that is driven by the crankshaft of internal
combustion engine 10. Alternatively, sprocket 64 may be a pulley
driven by a belt or other any other known drive member known for
driving camshaft phaser 12 by the crankshaft. In an alternative
arrangement, sprocket 64 may be integrally formed or otherwise
attached to stator 18 rather than back cover 22.
[0030] Similarly, front cover 24 is sealingly secured, using cover
bolts 60, to the axial end of stator 18 that is opposite back cover
22. Cover bolts 60 pass through back cover 22 and stator 18 and
threadably engage front cover 24; thereby clamping stator 18
between back cover 22 and front cover 24 to prevent relative
rotation between stator 18, back cover 22, and front cover 24. In
this way, advance chambers 42 and retard chambers 44 are defined
axially between back cover 22 and front cover 24. Front cover 24
includes a front cover central bore 66 extending coaxially
therethrough and a front cover counter bore 68 extending coaxially
thereinto from the side of front cover 24 which is adjacent to
stator 18. A front cover annular projection 70 extends axially from
the bottom of front cover counter bore 68 toward rotor 20 such that
front cover annular projection 70 in parts defines front cover
central bore 66 and such that front cover annular projection 70
defines, together with front cover counter bore 68, a front cover
annular recess 72.
[0031] Camshaft phaser 12 is attached to camshaft 14 with camshaft
phaser attachment bolt 26 which extends coaxially through rotor
central through bore 40 of rotor 20 and threadably engages camshaft
14, thereby by clamping rotor 20 securely to camshaft 14. More
specifically, rotor central hub inner portion 50 is clamped between
the head of camshaft phaser attachment bolt 26 and camshaft 14. In
this way, relative rotation between stator 18 and rotor 20 results
in a change in phase or timing between the crankshaft of internal
combustion engine 10 and camshaft 14.
[0032] Oil is selectively transferred to advance chambers 42 from
retard chambers 44, as result of torque applied to camshaft 14 from
the valve train of internal combustion engine 10, i.e. torque
reversals of camshaft 14, in order to cause relative rotation
between stator 18 and rotor 20 which results in retarding the
timing of camshaft 14 relative to the crankshaft of internal
combustion engine 10. Conversely, oil is selectively transferred to
retard chambers 44 from advance chambers 42, as result of torque
applied to camshaft 14 from the valve train of internal combustion
engine 10, in order to cause relative rotation between stator 18
and rotor 20 which results in advancing the timing of camshaft 14
relative to the crankshaft of internal combustion engine 10. Rotor
advance passages 74 may be provided in rotor 20 for supplying and
venting oil to and from advance chambers 42 while rotor retard
passages 76 may be provided in rotor 20 for supplying and venting
oil to and from retard chambers 44. Rotor advance passages 74
extend radially outward through rotor central hub outer portion 52
from annular valve spool recess 48 to advance chambers 42 while
rotor retard passages 76 extend radially outward through rotor
central hub outer portion 52 from annular valve spool recess 48 to
retard chambers 44. Transferring oil to advance chambers 42 from
retard chambers 44 and transferring oil to retard chambers 44 from
advance chambers 42 is controlled by valve spool 28 and phasing
check valves 78, as will be described in detail later, such that
valve spool 28 is disposed coaxially and rotatably within annular
valve spool recess 48. It should be noted that phasing check valves
78 are shown in FIGS. 4, 5B, 5F, 6B, 6F in simplified schematic
form in dotted lines in order to allow viewing of oil passages in
valve spool 28.
[0033] Rotor 20 and valve spool 28, which act together to function
as a valve, will now be described in greater detail with continued
reference to FIGS. 1-4. Valve spool 28 includes a spool central hub
80 with a spool central through bore 82 extending coaxially
therethrough. Valve spool 28 is received coaxially within annular
valve spool recess 48, and consequently, valve spool 28 radially
surrounds camshaft phaser attachment bolt 26. Spool central through
bore 82 is sized to mate with rotor central hub inner portion 50 in
a close sliding interface such that valve spool 28 is able to
freely rotate on rotor central hub inner portion 50 while
substantially preventing oil from passing between the interface of
spool central through bore 82 and rotor central hub inner portion
50 and also substantially preventing radial movement of valve spool
28 within annular valve spool recess 48. Spool central hub 80
extends axially from a spool hub first end 84 which is proximal to
rotor 20 to a spool hub second end 86 which is distal from rotor
20. Valve spool 28 also includes an annular spool base 88 which
extends radially outward from spool central hub 80 at spool hub
first end 84 such that annular spool base 88 axially abuts valve
spool recess shoulder 56. Valve spool 28 also includes an annular
spool top 90 which extends radially outward from spool central hub
80 such that annular spool top 90 axially abuts front cover annular
projection 70 of front cover 24 and such that annular spool top 90
is axially spaced from annular spool base 88. Consequently, annular
spool base 88 and annular spool top 90 are captured axially between
valve spool recess shoulder 56 and front cover 24 such that axial
movement of valve spool 28 relative to rotor 20 is substantially
prevented. Valve spool 28 also includes an annular spool dividing
wall 92 which extends radially outward from spool central hub 80
such that annular spool dividing wall 92 is axially between annular
spool base 88 and annular spool top 90. A plurality of valve spool
inner lands 94 extend radially outward from spool central hub 80 in
a polar array such that valve spool inner lands 94 join annular
spool base 88 and annular spool dividing wall 92, thereby defining
a plurality of alternating inner supply chambers 96 and inner vent
chambers 98 between annular spool base 88 and annular spool
dividing wall 92. The number of valve spool inner lands 94 is equal
to the sum of the number of advance chambers 42 and the number of
retard chambers 44, and as shown in the figures of the described
embodiment, there are six valve spool inner lands 94. A plurality
of valve spool outer lands 100 extend radially outward from spool
central hub 80 in a polar array such that valve spool outer lands
100 join annular spool dividing wall 92 and annular spool top 90,
thereby defining a plurality of alternating outer supply chambers
102 and outer vent chambers 104 between annular spool dividing wall
92 and annular spool top 90. The number of valve spool outer lands
100 is equal to the number of valve spool inner lands 94. Annular
spool dividing wall 92 includes a plurality of supply chamber
connecting passages 106 extend axially therethrough such that each
supply chamber connecting passage 106 provides fluid communication
between a respective inner supply chamber 96 and a respective outer
supply chamber 102. Similarly, annular spool dividing wall 92
includes a plurality of vent chamber connecting passages 108 extend
axially therethrough such that each vent chamber connecting passage
108 provides fluid communication between a respective inner vent
chamber 98 and a respective outer vent chamber 104.
[0034] Valve spool 28 also includes a valve spool band 110 which
radially surrounds outer supply chambers 102 and outer vent
chambers 104 such that valve spool band 110 is sealingly secured to
annular spool dividing wall 92 and annular spool top 90. A
reservoir 112 is defined radially between valve spool band 110 and
front cover counter bore 68 and also axially between annular spool
top 90 and front cover 24. Valve spool band 110 includes a
plurality of valve spool band supply passages 114 extending
radially therethrough and a plurality of valve spool band vent
passages 116 extending radially therethrough. Each valve spool band
supply passage 114 provides fluid communication between a
respective outer supply chamber 102 and reservoir 112 while each
valve spool band vent passage 116 provides fluid communication
between a respective outer vent chamber 104 and reservoir 112. Each
valve spool band supply passage 114 includes a respective phasing
check valve 78 which allows oil to flow from reservoir 112 to
respective outer supply chambers 102 while preventing oil from
flowing from outer supply chambers 102 to reservoir 112 as will be
described in greater detail later.
[0035] Annular spool base 88 includes oil make-up passages 120
extending axially therethrough which provide fluid communication
between respective inner vent chambers 98 and an annular volume 122
defined axially between annular valve spool recess bottom 54 and
annular spool base 88. Annular volume 122 receives pressurized oil
from an oil source 124, for example, an oil pump of internal
combustion engine 10, via a rotor supply passage 126 formed in
rotor 20 and also via a camshaft supply passage 129 formed in
camshaft 14.
[0036] Valve spool 28 also includes a valve spool drive extension
128 which extends axially from annular spool top 90 and through
front cover central bore 66. Valve spool drive extension 128 and
front cover central bore 66 are sized to interface in a close
sliding fit which permits valve spool 28 to rotate freely relative
to front cover 24 while substantially preventing oil from passing
between the interface of valve spool drive extension 128 and front
cover central bore 66. Valve spool drive extension 128 is arranged
to engage an actuator 130 which is used to rotate valve spool 28
relative to stator 18 and rotor 20 as required to achieve a desired
rotational position of rotor 20 relative to stator 18 as will be
described in greater detail later. Actuator 130 may be, by way of
non-limiting example only, an electric motor which is stationary
relative to camshaft phaser 12 and connected to valve spool drive
extension 128 through a gear set or an electric motor which rotates
with camshaft phaser 12 and which is powered through slip rings.
Actuator 130 may be controlled by an electronic controller (not
shown) based on inputs from various sensors (not shown) which may
provide signals indicative of, by way of non-limiting example only,
engine temperature, ambient temperature, intake air flow, manifold
pressure, exhaust constituent composition, engine torque, engine
speed, throttle position, crankshaft position, and camshaft
position. Based on the inputs from the various sensors, the
electronic controller may determine a desired phase relationship
between the crankshaft and camshaft 14, thereby commanding actuator
130 to rotate valve spool 28 relative to stator 18 and rotor 20 as
required to achieve the desired rotational position of rotor 20
relative to stator 18.
[0037] A valve spool ring 132 is located radially between valve
spool 28 and the portion of annular valve spool recess 48 defined
by rotor central hub outer portion 52. Valve spool ring 132 is
fixed to rotor 20, for example only, by press fitting valve spool
ring 132 with annular valve spool recess 48, such that relative
rotation between valve spool ring 132 and rotor 20 is prevented.
Valve spool ring 132 is sized to substantially prevent oil from
passing between the interface between valve spool ring 132 and
annular valve spool recess 48. Valve spool ring 132 includes a
plurality of valve spool ring advance passages 134 and a plurality
of valve spool ring retard passages 136 which extend radially
therethrough. Each valve spool ring advance passage 134 is aligned
with a respective rotor advance passage 74 while each valve spool
ring retard passage 136 is aligned with a respective rotor retard
passage 76. Each valve spool ring advance passage 134 and each
valve spool ring retard passage 136 is sized to be equal to the
width of valve spool inner lands 94, and the spacing between valve
spool ring advance passages 134 and valve spool ring retard
passages 136 matches the spacing between valve spool inner lands
94. Valve spool inner lands 94 engage the inner circumference of
valve spool ring 132 to substantially prevent oil from passing
between the interfaces of valve spool inner lands 94 and valve
spool ring 132 while allowing valve spool 28 to rotate within valve
spool ring 132 substantially uninhibited. Consequently, inner
supply chambers 96 and inner vent chambers 98 are fluidly
segregated and fluid communication into and out of advance chambers
42 and retard chambers 44 is substantially prevented when valve
spool inner lands 94 are aligned with valve spool ring advance
passages 134 and valve spool ring retard passages 136 to block
valve spool ring advance passages 134 and valve spool ring retard
passages 136.
[0038] Operation of camshaft phaser 12 will now be described with
continued reference to FIGS. 1-4 and now with additional reference
to FIGS. 5A-6F. The rotational position of rotor 20 relative to
stator 18 is determined by the rotational position of valve spool
28 relative to stator 18. When the rotational position of rotor 20
relative to stator 18 is at a desired position to achieve desired
operational performance of internal combustion engine 10, the
rotational position of valve spool 28 relative to stator 18 is
maintained constant by actuator 130. Consequently, a hold position
as shown in FIGS. 3 and 4 is defined when each valve spool inner
land 94 is aligned with a respective valve spool ring advance
passage 134 or a respective valve spool ring retard passage 136,
thereby preventing fluid communication into and out of advance
chambers 42 and retard chambers 44 and hydraulically locking the
rotational position of rotor 20 relative to stator 18. In this way,
the phase relationship between camshaft 14 and the crankshaft is
maintained.
[0039] As shown in FIGS. 5A-5F, if a determination is made to
advance the phase relationship between camshaft 14 and the
crankshaft, it is necessary to rotate rotor 20 clockwise relative
to stator 18 as viewed in the figures and as embodied by camshaft
phaser 12. In order to rotate rotor 20 to the desired rotational
position relative to stator 18, actuator 130 causes valve spool 28
to rotate clockwise relative to stator 18 to a rotational position
of valve spool 28 relative to stator 18 that will also determine
the rotational position of rotor 20 relative to stator 18. When
valve spool 28 is rotated clockwise relative to stator 18, valve
spool inner lands 94 are moved out of alignment with valve spool
ring advance passages 134 and valve spool ring retard passages 136,
thereby providing fluid communication between inner supply chambers
96 and retard chambers 44 and also between inner vent chambers 98
and advance chambers 42. Consequently, torque reversals of camshaft
14 which tend to pressurize oil within advance chambers 42 cause
oil to be communicated from advance chambers 42 to retard chambers
44 via rotor advance passages 74, valve spool ring advance passages
134, inner vent chambers 98, vent chamber connecting passages 108,
outer vent chambers 104, valve spool band vent passages 116,
reservoir 112, valve spool band supply passages 114, outer supply
chambers 102, supply chamber connecting passages 106, inner supply
chambers 96, valve spool ring retard passages 136, and rotor retard
passages 76. However, torque reversals of camshaft 14 which tend to
pressurize oil within retard chambers 44 and apply a
counterclockwise torque to rotor 20 are prevented from venting oil
from retard chambers 44 because phasing check valves 78 prevent oil
from flowing out of outer supply chambers 102 and being supplied to
advance chambers 42. Oil continues to be supplied to retard
chambers 44 from advance chambers 42 until rotor 20 is rotationally
displaced sufficiently far for each valve spool inner land 94 to
again align with respective valve spool ring advance passages 134
and valve spool ring retard passages 136 as shown in FIG. 5C,
thereby again preventing fluid communication into and out of
advance chambers 42 and retard chambers 44 and hydraulically
locking the rotational position of rotor 20 relative to stator 18.
In FIGS. 5D, 5E, and 5F, which are the same cross-sectional views
of FIGS. 2, 5A, and 5B respectively, the reference numbers have
been removed for clarity, and arrows R have been included to
represent oil that is being recirculated for rotating rotor 20
relative to stator 18. It should be noted that FIGS. 5D and 5F show
phasing check valves 78 being opened, but phasing check valves 78
may also be closed depending on the direction of the torque
reversal of camshaft 14 at a particular time.
[0040] Conversely, as shown in FIGS. 6A-6F, if a determination is
made to retard the phase relationship between camshaft 14 and the
crankshaft, it is necessary to rotate rotor 20 counterclockwise
relative to stator 18 as viewed in the figures and as embodied by
camshaft phaser 12. In order to rotate rotor 20 to the desired
rotational position relative to stator 18, actuator 130 causes
valve spool 28 to rotate counterclockwise relative to stator 18 to
a rotational position of valve spool 28 relative to stator 18 that
will also determine the rotational position of rotor 20 relative to
stator 18. When valve spool 28 is rotated counterclockwise relative
to stator 18, valve spool inner lands 94 are moved out of alignment
with valve spool ring advance passages 134 and valve spool ring
retard passages 136, thereby providing fluid communication between
inner supply chambers 96 and advance chambers 42 and also between
inner vent chambers 98 and retard chambers 44. Consequently, torque
reversals of camshaft 14 which tend to pressurize oil within retard
chambers 44 cause oil to be communicated from retard chambers 44 to
advance chambers 42 via rotor retard passages 76, valve spool ring
retard passages 136, inner vent chambers 98, vent chamber
connecting passages 108, outer vent chambers 104, valve spool band
vent passages 116, reservoir 112, valve spool band supply passages
114, outer supply chambers 102, supply chamber connecting passages
106, inner supply chambers 96, valve spool ring advance passages
134, and rotor advance passages 74. However, torque reversals of
camshaft 14 which tend to pressurize oil within advance chambers 42
and apply a clockwise torque to rotor 20 are prevented from venting
oil from advance chambers 42 because phasing check valves 78
prevent oil from flowing out of outer supply chambers 102 and being
supplied to retard chambers 44. Oil continues to be supplied to
advance chambers 42 from retard chambers 44 until rotor 20 is
rotationally displaced sufficiently far for each valve spool inner
land 94 to again align with respective valve spool ring advance
passages 134 and valve spool ring retard passages 136 as shown in
FIG. 6C, thereby again preventing fluid communication into and out
of advance chambers 42 and retard chambers 44 and hydraulically
locking the rotational position of rotor 20 relative to stator 18.
In FIGS. 6D, 6E, and 6F, which are the same cross-sectional views
of FIGS. 2, 6A, and 6B respectively, the reference numbers have
been removed for clarity, and arrows R have been included to
represent oil that is being recirculated for rotating rotor 20
relative to stator 18. It should be noted that FIGS. 6D and 6F show
phasing check valves 78 being opened, but phasing check valves 78
may also be closed depending on the direction of the torque
reversal of camshaft 14 at a particular time.
[0041] It is important to note that oil exclusively flows from
inner supply chambers 96 to whichever of advance chambers 42 and
retard chambers 44 need to increase in volume in order to achieve
the desired phase relationship of rotor 20 relative to stator 18
while oil exclusively flows to inner vent chambers 98 from
whichever of advance chambers 42 and retard chambers 44 need to
decrease in volume in order to achieve the desired phase
relationship of rotor 20 relative to stator 18. In this way, only
one set of phasing check valves 78 are needed acting in one
direction within valve spool 28 in order to achieve the desired
phase relationship of rotor 20 relative to stator 18. Consequently,
it is not necessary to switch between sets of check valves
operating in opposite flow directions or switch between an
advancing circuit and a retarding circuit. In the case of the
position control valve described herein, a unidirectional flow
circuit is defined within valve spool 28 when valve spool 28 is
moved to a position within rotor 20 to allow either flow from
advance chambers 42 to retard chambers 44 or from retard chambers
44 to advance chambers 42 where the flow circuit prevents flow in
the opposite directions. Consequently, the flow circuit is defined
by valve spool 28 which is simple in construction and low cost to
produce.
[0042] In operation, the actual rotational position of rotor 20
relative to stator 18 may drift over time from the desired
rotational position of rotor 20 relative to stator 18, for example
only, due to leakage from advance chambers 42 and/or retard
chambers 44. Leakage from advance chambers 42 and/or retard
chambers 44 may be the result of, by way of non-limiting example
only, manufacturing tolerances or wear of the various components of
camshaft phaser 12. An important benefit of valve spool 28 is that
valve spool 28 allows for self-correction of the rotational
position of rotor 20 relative to stator 18 if the rotational
position of rotor 20 relative to stator 18 drifts from the desired
rotational position of rotor 20 relative to stator 18. Since the
rotational position of valve spool 28 relative to stator 18 is
locked by actuator 130, valve spool ring advance passages 134 and
valve spool ring retard passages 136 will be moved out of alignment
with valve spool inner lands 94 when rotor 20 drifts relative to
stator 18. Consequently, oil will flow to advance chambers 42 from
retard chambers 44 and oil will flow from advance chambers 42 to
retard chambers 44 as necessary to rotate rotor 20 relative to
stator 18 to correct for the drift until each valve spool inner
land 94 is again aligned with respective valve spool ring advance
passages 134 and valve spool ring retard passages 136.
[0043] It should be noted that oil that may leak from camshaft
phaser 12 is replenished from oil provided by oil source 124.
Replenishing oil is accomplished by oil source 124 supplying oil to
reservoir 112 via camshaft supply passage 129, rotor supply passage
126, annular volume 122, oil make-up passages 120, inner vent
chambers 98, vent chamber connecting passages 108, outer vent
chambers 104, and valve spool band vent passages 116. From
reservoir 112, the oil may be supplied to advance chambers 42 or
retard chambers 44 as necessary by one or more of the processes
described previously for advancing, retarding, or correcting for
drift.
[0044] It should be noted that opposing axial ends of valve spool
28 are at a common pressure because reservoir 112 and annular
volume 122 are in constant fluid communication via oil make-up
passages 120, inner vent chambers 98, vent chamber connecting
passages 108, outer vent chambers 104, and valve spool band vent
passages 116. Maintaining opposing axial ends of valve spool 28 at
a common pressure prevents hydraulic pressure from applying an
axial load to valve spool 28.
[0045] While camshaft phaser 12 has been described as including
valve spool ring 132, it should now be understood that valve spool
ring 132 may be omitted. If valve spool ring 132 is omitted, then
valve spool inner lands 94 interface directly with the surface of
annular valve spool recess 48 defined by rotor central hub outer
portion 52. Furthermore, rotor advance passages 74 and rotor retard
passages 76 need to be equal to the width of valve spool inner
lands 94 when valve spool ring 132 is omitted, and the spacing
between rotor advance passages 74 and rotor retard passages 76
matches the spacing between valve spool inner lands 94.
[0046] While phasing check valves 78 have been described in the
embodiment herein as being located within outer supply chambers
102, it should now be understood that phasing check valves 78 could
be located in numerous other locations which prevent flow from
inner supply chambers 96 to inner vent chambers 98. By way of
non-limiting example only, phasing check valves 78 could be located
between reservoir 112 and outer vent chambers 104. In another
configuration, outer supply chambers 102 may be commonly connected
to a first common passage and outer vent chambers 104 may be
commonly connected to a second common passage where one or more
phasing check valves 78 allow flow from the second common passage
to the first common passage while preventing flow from the first
common passage to the second common passage.
[0047] While clockwise rotation of rotor 20 relative to stator 18
has been described as advancing camshaft 14 and counterclockwise
rotation of rotor 20 relative to stator 18 has been described as
retarding camshaft 14, it should now be understood that this
relationship may be reversed depending on whether camshaft phaser
12 is mounted to the front of internal combustion engine 10 (shown
in the figures) or to the rear of internal combustion engine
10.
[0048] While this invention has been described in terms of
preferred embodiments thereof, it is not intended to be so limited,
but rather only to the extent set forth in the claims that
follow.
* * * * *