TECHNICAL FIELD
[0001] The present invention relates to an internal combustion engine with a camshaft phaser
which uses pressurized oil to vary the phase relationship between a crankshaft and
a camshaft of the internal combustion engine; more particularly to such an internal
combustion engine which includes a drive belt for transmitting rotational motion from
the crankshaft to the camshaft; and still even more particularly to such an internal
combustion engine which includes a sealing arrangement to seal the drive belt from
the oil used to vary the phase relationship between the crankshaft and the camshaft.
BACKGROUND OF THE 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 either the advance chambers or the
retard chambers and vented from the other of the advance and retard chambers in order
to rotate the rotor within the stator and thereby change the phase relationship between
the camshaft and the crankshaft. Some camshaft phasers include a valve spool within
the camshaft phaser in order to selectively supply and vent oil to and from the advance
and retard chambers as necessary in order to achieve the desired phase relationship
between the camshaft and the crankshaft. When the oil is vented from either the advance
chambers or the retard chambers, the oil is typically drained out of the camshaft
phaser and allowed to reach a drive member, such as a chain, gear, or belt, which
transfers rotational motion from the crankshaft to the camshaft phaser. While this
may be acceptable to some drive members, particularly chains and gears, other drive
members, particularly belts, may not tolerate exposure to oil.
[0003] United States Patent No.
5,361,735 to Butterfield et al. teaches a camshaft phaser having a flexible diaphragm at one axial end thereof to
prevent oil from the camshaft phaser from reaching the drive belt. The flexible diaphragm
is positioned between a valve spool and an actuator which alters the position of the
valve spool. Consequently, the actuator pushes on the valve spool through the flexible
diaphragm during operation. Since the flexible diaphragm is rotating at the rotational
speed of the camshaft during operation and the rotational actuator is rotationally
stationary, durability issues with the flexible diaphragm may result, particularly
if there is misalignment in concentricity between the actuator and the center of the
flexible diaphragm.
[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, an internal combustion engine includes a crankshaft rotatable
about a crankshaft axis and a camshaft rotatable by the crankshaft about a camshaft
axis. The internal combustion engine also includes an oil supply, an engine cover,
and a drive member disposed within the engine cover for transferring rotational motion
from the crankshaft to the camshaft. A camshaft phaser is disposed within the engine
cover for controllably varying the phase relationship between the crankshaft and the
camshaft. The camshaft phaser includes an input member driven by the drive member,
an output member rotatable with the camshaft wherein the output member is rotatable
relative to the input member by oil from the oil supply thereby varying the phase
relationship between the crankshaft and the camshaft, and a valve spool within the
camshaft phaser and moveable therein between 1) an advance position to direct oil
from the oil supply to cause the input member to rotate relative to the output member
to advance the camshaft relative to the crankshaft and 2) a retard position to direct
oil from the oil supply to cause the input member to rotate relative to the output
member to retard the camshaft relative to the crankshaft. An actuator moves the valve
spool between the advance position and the retard position and a sealing arrangement
defines a dry zone with one of the engine cover and the actuator to isolate the drive
member from oil used to rotate the output member relative to the input member.
[0006] Moreover the input member is a stator having a plurality of lobes. The output member
is a rotor disposed within the stator. In addition the rotor has a plurality of vanes
interspersed with the lobes. The rotor is rotatable within the stator about the camshaft
axis and defining alternating advance chambers and retard chambers. The advance chambers
also receive oil in order to change the phase relationship between the crankshaft
and the camshaft in an advance direction. Further the retard chambers receive oil
in order to change the phase relationship between the camshaft and the crankshaft
in a retard direction. The camshaft phaser further comprises a front cover closing
off one end of the stator. The sealing arrangement further comprises an engine cover
to camshaft phaser seal to seal between the engine cover and the front cover or between
the actuator and the front cover. The engine cover to camshaft phaser seal is a radial
seal. In addition the camshaft phaser rotates relative to the engine cover to camshaft
phaser seal. The engine cover also includes a ring-shaped engine cover seal support
extending axially from the engine cover toward the camshaft phaser and the engine
cover to camshaft phaser seal is fixed to the engine cover seal support. Moreover
the front cover includes a ring-shaped front cover sealing body extending axially
from the front cover toward the engine cover such that the engine cover to camshaft
phaser seal seals against the front cover sealing body. The camshaft phaser further
comprises a back cover closing off the other end of said stator, the back cover including
a back cover central bore extending axially therethrough. Furthermore the internal
combustion engine comprises a camshaft support which supports said camshaft. The sealing
arrangement further comprises an engine to camshaft phaser seal to seal between the
camshaft phaser and the camshaft support. The engine to camshaft phaser seal is a
radial seal. Further the camshaft phaser rotates relative to the engine to camshaft
phaser seal. The camshaft support defines a camshaft support bore and the engine to
camshaft phaser seal is located within the camshaft support bore. The back cover also
includes a ring-shaped back cover sealing body extending axially from the back cover
into the camshaft support bore such that the engine to camshaft phaser seal seals
against said back cover sealing body. The engine cover to camshaft phaser seal is
fixed to the actuator. The actuator also includes an actuator seal bore extending
axially into the actuator and the engine cover to camshaft phaser seal is fixed within
the actuator seal bore.
[0007] In another embodiment, an internal combustion engine has a crankshaft rotatable about
a crankshaft axis and a camshaft rotatable by the crankshaft about a camshaft axis.
The internal combustion engine also comprises an oil supply, an engine cover, a drive
member disposed within the engine cover for transferring rotational motion from the
crankshaft to the camshaft, a camshaft phaser disposed within the engine cover for
controllably varying the phase relationship between the crankshaft and the camshaft.
The camshaft phaser also comprises an input member driven by the drive member, an
output member rotatable with the camshaft. Further the output member is rotatable
relative to the input member by oil from the oil supply, thereby varying the phase
relationship between the crankshaft and the camshaft and a valve spool within the
camshaft phaser and moveable therein for directing oil from the oil supply. The camshaft
phaser also comprises an actuator for moving the valve spool and a sealing arrangement
defining a dry zone with one of the engine cover and the actuator to isolate the drive
member from oil directed by the valve spool. The input member is a stator having a
plurality of lobes. The output member is a rotor disposed within the stator, the rotor
having a plurality of vanes interspersed with the lobes) such that the rotor is rotatable
within the stator about the camshaft axis and defining alternating advance chambers
and retard chambers. The advance chambers also receive oil in order to change the
phase relationship between the crankshaft and the camshaft in an advance direction
and the retard chambers receive oil in order to change the phase relationship between
the camshaft and the crankshaft in a retard direction. The camshaft phaser further
comprises a front cover closing off one end of the stator. The sealing arrangement
comprises an engine cover to camshaft phaser seal to seal between the engine cover
and the front cover or between the actuator and the front cover. The engine cover
also includes a ring-shaped engine cover seal support extending axially from the engine
cover toward the camshaft phaser and the engine cover to camshaft phaser seal is fixed
to the engine cover seal support. Moreover the front cover includes a ring-shaped
front cover sealing body extending axially from the front cover toward the engine
cover. The engine cover to camshaft phaser seal seals against the front cover sealing
body. The camshaft phaser further comprises a back cover closing off the other end
of the stator. The back cover includes a back cover central bore extending axially
therethrough. The internal combustion engine further comprises a camshaft support
which supports the camshaft and the sealing arrangement further comprising an engine
to camshaft phaser seal to seal between the camshaft phaser and the camshaft support.
The camshaft support defines a camshaft support bore and the engine to camshaft phaser
seal is located within the camshaft support bore. The back cover includes a ring-shaped
back cover sealing body extending axially from the back cover into the camshaft support
bore such that the engine to camshaft phaser seal seals against the back cover sealing
body. Moreover the engine cover to camshaft phaser seal is fixed to the actuator.
The actuator also includes an actuator seal bore extending axially into the actuator
and the engine cover to camshaft phaser seal is fixed within the actuator seal bore.
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 THE DRAWINGS
[0008] This invention will be further described with reference to the accompanying drawings
in which:
Fig. 1 is an exploded isometric view of an internal combustion engine in accordance
with the present invention;
Fig. 2 is an axial cross-sectional view of the internal combustion engine in accordance
with the present invention;
Fig. 3 is a radial cross-sectional view of a camshaft phaser of the internal combustion
engine in accordance with the present invention;
Fig. 4A is an axial cross-sectional view of the camshaft phaser, taken through section
line 4-4 of Fig. 3, showing an actuator in an energized state of operation;
Fig. 4B is an axial cross-sectional view of the camshaft phaser, taken through section
line 4-4 of Fig. 3, showing the actuator in an unenergized state of operation;
Fig. 5 is an enlargement of a portion of Fig. 2;
Fig. 6 is an axial cross-sectional view of an alternative internal combustion engine
in accordance with the present invention; and
Fig. 7 is an axial cross-sectional view of another alternative internal combustion
engine in accordance with the present invention.
DESCRIPTION OF THE PREFERED EMBODIMENT
[0009] Referring to Figs. 1 and 2, an internal combustion engine 10 is shown in accordance
with the present invention. Internal combustion engine 10 generally includes one or
more pistons (not shown), a crankshaft 12 which rotates about a crankshaft axis 14,
a camshaft 16 which is supported in a camshaft support 18 and rotates about a camshaft
axis 20, and a camshaft phaser 22 which rotates about camshaft axis 20. Internal combustion
engine 10 may be, for example only, spark ignited or compression ignited and may be
fueled by any liquid fuel or gaseous fuel customarily used, for example only, liquid
fuels such as gasoline, diesel fuel, alcohol, ethanol, and the like and blends thereof
or gaseous fuels such as natural gas, propane, and the like. The pistons, which are
connected to crankshaft 12, reciprocate as a result of combustion of the fuel within
the respective combustion chambers (not shown). Reciprocation of the pistons causes
crankshaft 12 to rotate about crankshaft axis 14. Crankshaft 12 includes a crankshaft
pulley 24 which may be toothed as shown and which rotates a drive member 26, for example,
drive belt which is toothed to mate with crankshaft pulley 24. Camshaft phaser 22
is rotated by drive member 26 and is connected to camshaft 16, consequently, camshaft
16 rotates about camshaft axis 20 as a result of crankshaft 12. Rotation of camshaft
16 about camshaft axis 20 causes one or more combustion valves (not shown) to open
and close. The combustion valves allow a charge of air and/or fuel into the combustion
chambers and/or exhaust constituents out of the combustion chambers. Camshaft phaser
22 allows the phase of rotation of camshaft 16 relative to crankshaft 12 to be varied,
thereby varying the timing of opening and/or closing of the combustion valves relative
to crankshaft 12 as will be described in greater detail later. An engine cover 28
encloses crankshaft pulley 24, drive member 26, and camshaft phaser 22.
[0010] With continued reference to Figs. 1 and 2 and now with additional reference to Fig.
3, camshaft phaser 22 uses pressurized oil to change the phase relationship of camshaft
16 relative to crankshaft 12. As shown, camshaft phaser 22 is what is commonly referred
to in the art as a vane-type camshaft phaser.
[0011] Camshaft phaser 22 generally includes a stator 30 which acts as an input member,
a rotor 32 which acts as an output member and which is disposed coaxially within stator
30, a back cover 34 closing off one end of stator 30, a front cover 36 closing off
the other end of stator 30, a camshaft phaser attachment bolt 40 for attaching camshaft
phaser 22 to camshaft 16, and a valve spool 42 for controlling oil as will be described
later which is supplied by an oil supply 44 of internal combustion engine 10. An actuator
46 is provided for positioning valve spool 42 to achieve a desired rotational position
of rotor 32 relative to stator 30 as will also be described later. The various elements
of camshaft phaser 22 will be described in greater detail in the paragraphs that follow.
[0012] Stator 30 is generally cylindrical and includes a plurality of radial chambers 48
(only one radial chamber 48 is labeled in Fig. 1) defined by a plurality of lobes
50 extending radially inward. In the embodiment shown, there are four lobes 50 defining
four radial chambers 48, however, it is to be understood that a different number of
lobes 50 may be provided to define radial chambers 48 equal in quantity to the number
of lobes 50. Stator 30 may also include a camshaft phaser pulley 52 which is toothed
as shown and formed integrally therewith or otherwise fixed thereto. Camshaft phaser
pulley 52 is configured to be driven by drive member 26. While the drive arrangement
between crankshaft 12 and camshaft phaser 22 has been illustrated as using pulleys
and a belt, it should now be understood that other drive arrangements may be used,
for example only, sprockets and a chain or gears.
[0013] Rotor 32 includes a central hub 54 with a plurality of vanes 56 extending radially
outward therefrom and a central through bore 58 extending axially therethrough. The
number of vanes 56 is equal to the number of radial chambers 48 provided in stator
30. Rotor 32 is coaxially disposed within stator 30 such that each vane 56 divides
each radial chamber 48 into advance chambers 60 and retard chambers 62. The radial
tips of lobes 50 are mateable with central hub 54 in order to separate radial chambers
48 from each other. Each of the radial tips of lobes 50 and the tips of vanes 56 may
include one of a plurality of wiper seals 64 to substantially seal adjacent advance
chambers 60 and retard chambers 62 from each other.
[0014] Back cover 34 is sealingly secured, using cover bolts 66, to the axial end of stator
30 that is proximal to camshaft 16. A back cover seal 68, for example only, an o-ring,
may be provided between back cover 34 and stator 30 in order to provide an oil-tight
seal between the interface of back cover 34 and stator 30. Tightening of cover bolts
66 prevents relative rotation between back cover 34 and stator 30. Back cover 34 includes
a back cover central bore 70 extending coaxially therethrough. The end of camshaft
16 is received coaxially within back cover central bore 70 such that camshaft 16 is
allowed to rotate relative to back cover 34. In an alternative arrangement, camshaft
phaser pulley 52 may be integrally formed or otherwise attached to back cover 34 rather
than to stator 30 as described previously.
[0015] Similarly, front cover 36 is sealingly secured, using cover bolts 66, to the axial
end of stator 30 that is opposite back cover 34. A front cover seal 72, for example
only, an o-ring, may be provided between front cover 36 and stator 30 in order to
provide an oil-tight seal between the interface of front cover 36 and stator 30. Cover
bolts 66 pass through back cover 34 and stator 30 and threadably engage front cover
36, thereby clamping stator 30 between back cover 34 and front cover 36 to prevent
relative rotation between stator 30, back cover 34, and front cover 36. In this way,
advance chambers 60 and retard chambers 62 are defined axially between back cover
34 and front cover 36.
[0016] Camshaft phaser 22 is attached to camshaft 16 with camshaft phaser attachment bolt
40 which extends coaxially through central through bore 58 of rotor 32 and threadably
engages camshaft 16, thereby clamping rotor 32 securely to camshaft 16. In this way,
relative rotation between stator 30 and rotor 32 results in a change in phase relationship
or timing between crankshaft 12 and camshaft 16.
[0017] With continued reference to Figs. 1-3 and now with additional reference to Figs.
4A, 4B, and 5, pressurized oil is selectively supplied to advance chambers 60 and
vented from retard chambers 62 in order to cause relative rotation between stator
30 and rotor 32 which results in advancing the timing of camshaft 16 relative to crankshaft
12. Conversely, oil is selectively supplied to retard chambers 62 and vented from
advance chambers 60 in order to cause relative rotation between stator 30 and rotor
32 which results in retarding the timing of camshaft 16 relative to crankshaft 12.
Advance oil passages 74 may be provided in rotor 32 for supplying and venting oil
to and from advance chambers 60 while retard oil passages 76 may be provided in rotor
32 for supplying and venting oil to and from retard chambers 62. Supplying and venting
of oil to and from advance chambers 60 and retard chambers 62 is controlled by valve
spool 42, as will be discussed in the paragraphs that follow, which is coaxially disposed
slidably within a valve bore 78 of camshaft phaser attachment bolt 40 such that valve
bore 78 is centered about camshaft axis 20.
[0018] Oil supply 44 provides a supply of pressurized oil to valve spool 42 through radial
camshaft passages 80 which communicate with a camshaft counterbore 82 which forms
a camshaft annular oil passage 84 with a portion of camshaft phaser attachment bolt
40. The oil then passes from camshaft annular oil passage 84 to an axial rotor oil
passage 86 which extends axially into rotor 32. The oil is subsequently communicated
to an annular rotor oil supply groove 88 which extends radially outward from central
through bore 58 and intersects axial rotor oil supply passage 86. Annular rotor oil
supply groove 88 is axially aligned with bolt oil supply passages 90 which extend
radially through camshaft phaser attachment bolt 40 from valve bore 78. In this way,
oil from oil supply 44 is supplied to valve spool 42.
[0019] Valve spool 42 includes a body 92 that is generally cylindrical, hollow, and dimensioned
to provide annular clearance between body 92 and valve bore 78 of camshaft phaser
attachment bolt 40. Valve spool 42 also includes an advance land 94 extending radially
outward from body 92 for selectively blocking fluid communication between bolt oil
supply passages 90 and advance bolt passages 96 which extend radially outward through
camshaft phaser attachment bolt 40 from valve bore 78 and communicate with advance
oil passages 74 of rotor 32 through an annular rotor advance oil groove 98 which extends
radially outward from central through bore 58. Advance land 94 fits within valve bore
78 of camshaft phaser attachment bolt 40 in a close fitting relationship to substantially
prevent oil from passing between advance land 94 and valve bore 78. Valve spool 42
also includes a retard land 100 extending radially outward from body 92 for selectively
blocking fluid communication between bolt oil supply passages 90 and retard bolt passages
102 which extend radially outward through camshaft phaser attachment bolt 40 from
valve bore 78 and communicate with retard oil passages 76 of rotor 32 through an annular
rotor retard oil groove 104 which extends radially outward from central through bore
58. Retard land 100 is spaced axially from advance land 94 and fits within valve bore
78 of camshaft phaser attachment bolt 40 in a close fitting relationship to substantially
prevent oil from passing between retard land 100 and valve bore 78.
[0020] Valve spool 42 is axially moveable within valve bore 78 with input from actuator
46 and a spool spring 106 which is positioned axially between valve spool 42 and the
bottom of valve bore 78. When actuator 46 is in an unenergrized state of operation
as shown in Fig. 4B, valve spool 42 is positioned in a retard position, by force of
spool spring 106, to allow pressurized oil to be supplied to retard chambers 62 as
shown by arrows P. At the same time, oil within advance chambers 60 is allowed to
be vented through a central passage 108 formed coaxially through valve spool 42 and
then out through the end of valve bore 78 as shown by arrows V.
[0021] Conversely, when actuator 46 is in an energized state of operation as shown in Fig.
4A, valve spool 42 is positioned in an advance position, by force from actuator 46
overcoming force of spool spring 106, to allow pressurized oil to be supplied to advance
chambers 60 as shown by arrows P. At the same time, oil within retard chambers 62
is allowed to be vented through the end of valve bore 78 as shown by arrows V.
[0022] Drive member 26 may not be compatible with the oil supplied to camshaft phaser 22,
consequently, a dry zone 110 may be formed within engine cover 28. Drive member 26
is located within dry zone 110 which is substantially free of the oil supplied to
camshaft phaser 22. Dry zone 110 is formed by a sealing arrangement which may comprise
an engine cover to camshaft phaser seal 112 and an engine to camshaft phaser seal
114. The sealing arrangement will be described in greater detail in the paragraphs
that follow.
[0023] Referring now to Figs. 1, 2, and 5, engine cover to camshaft phaser seal 112 provides
a seal between engine cover 28 and front cover 36. Engine cover 28 includes an engine
cover seal support 116 which is ring-shaped and substantially centered about camshaft
axis 20. Engine cover seal support 116 extends axially away from engine cover 28 toward
camshaft phaser 22 into dry zone 110. Engine cover to camshaft phaser seal 112 includes
an engine cover to camshaft phaser seal supporting body 118 which is ring shaped and
secured coaxially within engine cover seal support 116, for example, by a press fit.
Alternatively, engine cover to camshaft phaser seal supporting body 118 may be secured
to engine cover seal support 116 by surrounding engine cover seal support 116, i.e.
the radial relationship between engine cover to camshaft phaser seal supporting body
118 and engine cover seal support 116 may be reversed from the relationship shown
in the figures. Engine cover to camshaft phaser seal supporting body 118 may be made
of a rigid material, for example, metal or plastic. Engine cover to camshaft phaser
seal 112 also includes an engine cover to camshaft phaser seal lip seal 120 which
extends radially inward from engine cover to camshaft phaser seal supporting body
118. Engine cover to camshaft phaser seal lip seal 120 may be molded and bonded to
engine cover to camshaft phaser seal supporting body 118 and may be made of an elastomeric
or rubber-like material, for example only, Nitrile Butadiene Rubber (NBR), VitonĀ®,
or silicone. Front cover 36 includes a front cover sealing body 122 for radially mating
with engine cover to camshaft phaser seal lip seal 120. Front cover sealing body 122
may include a sleeve (not show) in a radially surrounding relationship which provides
the necessary harness and surface finish to withstand rubbing with respect to engine
cover to camshaft phaser seal lip seal 120, however, the sleeve may be omitted as
shown if front cover sealing body 122 is made from a material of adequate hardness
and surface finish. Front cover sealing body 122 is ring-shaped and extends axially
away from front cover 36 toward engine cover 28 in a coaxial relationship with engine
cover seal support 116. Front cover sealing body 122 is sized to elastically deform
engine cover to camshaft phaser seal lip seal 120 when assembled in order to provide
an oil-tight seal between front cover sealing body 122 and engine cover to camshaft
phaser seal lip seal 120. Engine cover to camshaft phaser seal lip seal 120 is sized
to provide sufficient compliance to accommodate mismatch in concentricity between
engine cover to camshaft phaser seal 112 and front cover sealing body 122 due to manufacturing
tolerances. In this way, oil that is vented from advance chambers 60 and retard chambers
62 through the end of valve bore 78 is prevented from entering dry zone 110 as camshaft
phaser 22 rotates with respect to engine cover to camshaft phaser seal 112 in operation.
In addition to engine cover to camshaft phaser seal lip seal 120, engine cover to
camshaft phaser seal 112 may include a dust seal lip which protects engine cover to
camshaft phaser seal lip seal 120 from external contamination that may have undesirable
effects on engine cover to camshaft phaser seal lip seal 120.
[0024] Engine to camshaft phaser seal 114 provides a seal between camshaft support 18 and
back cover 34. A camshaft support bore 124, which is cylindrical, extends into camshaft
support 18 in a coaxial relationship with camshaft 16. Engine to camshaft phaser seal
114 includes an engine to camshaft phaser seal supporting body 126 which is ring shaped
and secured coaxially within camshaft support bore 124, for example, by a press fit.
Engine to camshaft phaser seal supporting body 126 may be made of a rigid material,
for example, metal or plastic. Engine to camshaft phaser seal 114 also includes an
engine to camshaft phaser seal lip seal 128 which extends radially inward from engine
to camshaft phaser seal supporting body 126. Engine to camshaft phaser seal lip seal
128 may be molded and bonded to engine to camshaft phaser seal supporting body 126
and may be made of an elastomeric or rubber-like material, for example only, Nitrile
Butadiene Rubber (NBR), VitonĀ®, or silicone. Engine to camshaft phaser seal 114 may
also include an engine to camshaft phaser seal dust lip seal 130 which extends radially
inward from engine to camshaft phaser seal supporting body 126 and may be made from
the same material as engine to camshaft phaser seal lip seal 128. Engine to camshaft
phaser seal dust lip seal 130 protects engine to camshaft phaser seal lip seal 128
from external contamination that may have undesirable effects on engine to camshaft
phaser seal lip seal 128. Back cover 34 includes a back cover sealing body 132 for
radially mating with engine to camshaft phaser seal lip seal 128. Back cover sealing
body 132 is ring-shaped and extends axially away from back cover 34 into camshaft
support bore 124 in a coaxial relationship with camshaft support bore 124. Back cover
sealing body 132 is sized to elastically deform engine to camshaft phaser seal lip
seal 128 when assembled in order to provide an oil-tight seal between back cover sealing
body 132 and engine to camshaft phaser seal lip seal 128.
[0025] Engine cover 28 includes an engine cover bore 134 extending therethrough in a substantially
coaxial relationship with camshaft 16. Actuator 46 is received coaxially within engine
cover bore 134 and is fixed to engine cover 28 to prevent relative rotation between
engine cover 28 and actuator 46. An engine cover to actuator seal 136, which may be
an O-ring as shown, is disposed between actuator 46 and engine cover 28. In this way,
oil that is vented from advance chambers 60 and retard chambers 62 through the end
of valve bore 78 is prevented from exiting engine cover 28 between the interface of
engine cover 28 and actuator 46. It should be noted that engine cover to actuator
seal 136 is a static seal, unlike engine cover to camshaft phaser seal 112 and engine
to camshaft phaser seal 114 which are dynamic seals, since there is no relative movement
between engine cover 28 and actuator 46.
[0026] With continued reference to Figs, 1, 2, and 5 and now with additional reference to
Fig. 7, a rotor drain passage 138 is provided axially through central hub 54 of rotor
32 in order to return oil to oil supply 44 that is vented from advance chambers 60
and retard chambers 62 through the end of valve bore 78. In order for rotor drain
passage 138 to receive oil that has been vented from advance chambers 60 and retard
chambers 62, a washer 140 that is captured axially between camshaft phaser attachment
bolt 40 and rotor 32 may include a notch 142 therethrough to allow the vented oil
to enter rotor drain passage 138. The oil exits the rotor drain passage 138 that is
proximal to camshaft 16 and is prevented from entering dry zone 110 by engine to camshaft
phaser seal 114 and is subsequently returned to oil supply 44. It should be noted
that rotor drain passage 138 and notch 142 are also present in the other figures,
however, are not visible because of the particular sections that are shown.
[0027] Alternatively, as shown in Fig. 6, engine cover to camshaft phaser seal 112 may be
fixed to actuator 46' rather than to engine cover 28'. Actuator 46' includes an actuator
seal bore 144 which is substantially coaxial with camshaft 16. Engine cover to camshaft
phaser seal 112 may be secured coaxially within actuator seal bore 144, for example,
by press fit. Also alternatively, as shown in Fig. 7, actuator 46" may be provided
which is integrally housed as part of engine cover 28". Engine cover to camshaft phaser
seal 112 may be supported by engine cover seal support 116" which is configured similar
to engine cover seal support 116 as described previously.
[0028] While not shown, it should now be understood that camshaft phaser 22 may include
a bias spring that either partially or completely offsets the natural retarding torque
induced by the overall valve train friction, balances performance times, or helps
return the phaser to a default position of rotor 32 within stator 30. The bias spring
may be grounded at one end thereof to front cover 36 and may be attached at the other
end thereof to rotor 32 for biasing rotor 32 relative to stator 30.
[0029] 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.
1. An internal combustion engine (10) having a crankshaft (12) rotatable about a crankshaft
axis (14) and a camshaft (16) rotatable by said crankshaft (12) about a camshaft axis
(20), said internal combustion engine (10) comprising:
a) an oil supply (44);
b) an engine cover (28,28',28");
c) a drive member (26) disposed within said engine cover (28,28',28") for transferring
rotational motion from said crankshaft (12) to said camshaft (16);
d) a camshaft phaser (22) disposed within said engine cover (28,28',28") for controllably
varying the phase relationship between said crankshaft (12) and said camshaft (16),
said camshaft phaser (22) comprising:
i) an input member (30) driven by said drive member (26);
ii) an output member (32) rotatable with said camshaft (16)
wherein said output member (32) is rotatable relative to said input member (30) by
oil from said oil supply (44), thereby varying the phase relationship between said
crankshaft (12) and said camshaft (16); and
iii) a valve spool (42) within said camshaft phaser (22) and moveable therein between
1) an advance position to direct oil from said oil supply (44) to cause said input
member (30) to rotate relative to said output member (32) to advance said camshaft
(16) relative to said crankshaft (12) and 2) a retard position to direct oil from
said oil supply (44) to cause said input member (30) to rotate relative to said output
member (32) to retard said camshaft (16) relative to said crankshaft (12);
e) an actuator (46,46',46") for moving said valve spool (42) between said advance
position and said retard position; and
f) a sealing arrangement defining a dry zone (110) with one of said engine cover (28,28',28")
and said actuator (46,46',46") to isolate said drive member (26) from oil used to
rotate said output member (32) relative to said input member (30).
2. An internal combustion engine (10) as set in the preceding claim wherein:
said input member (30) is a stator (30) having a plurality of lobes (50);
said output member (32) is a rotor (32) disposed within said stator (30), said rotor
(32) having a plurality of vanes (56) interspersed with said lobes (50) such that
said rotor (32) is rotatable within said stator (30) about said camshaft axis (20)
and defining alternating advance chambers (60) and retard chambers (62), wherein said
advance chambers (60) receive oil in order to change the phase relationship between
said crankshaft (12) and said camshaft (16) in an advance direction and said retard
chambers (62) receive oil in order to change the phase relationship between said camshaft
(16) and said crankshaft (12) in a retard direction;
said camshaft phaser (22) further comprising a front cover (36) closing off one end
of said stator (30); and
said sealing arrangement comprising an engine cover to camshaft phaser seal (112)
to seal between said engine cover (28,28',28") and said front cover (36) or between
said actuator (46,46',46") and said front cover (36).
3. An internal combustion engine (10) as set in claim 2 wherein said engine cover to
camshaft phaser seal (112) is a radial seal.
4. An internal combustion engine (10) as set in any claims 2 and 3 wherein said camshaft
phaser (22) rotates relative to said engine cover to camshaft phaser seal (112).
5. An internal combustion engine (10) as set in any of the claims 2 to 4 wherein said
engine cover (28,28") includes a ring-shaped engine cover seal support (116,116")
extending axially from said engine cover (28, 28") toward said camshaft phaser (22)
and said engine cover to camshaft phaser seal (112) is fixed to said engine cover
seal support (116,116").
6. An internal combustion engine (10) as set in any of the claims 2 to 5 wherein said
front cover (36) includes a ring-shaped front cover sealing body (122) extending axially
from said front cover (36) toward said engine cover (28,28") such that said engine
cover to camshaft phaser seal (112) seals against said front cover sealing body (122).
7. An internal combustion engine (10) as set in any of the claims 2 to 6 wherein:
said camshaft phaser (22) further comprises a back cover (34) closing off the other
end of said stator (30), said back cover (34) including a back cover central bore
(70) extending axially therethrough;
said internal combustion engine (10) further comprising a camshaft support (18) which
supports said camshaft (16); and
said sealing arrangement further comprising an engine to camshaft phaser seal (114)
to seal between said camshaft phaser (22) and said camshaft support (18).
8. An internal combustion engine (10) as set in any of the claims 2 to 7 wherein said
engine to camshaft phaser seal (114) is a radial seal.
9. An internal combustion engine (10) as set in any of the claims 2 to 8 wherein said
camshaft phaser (22) rotates relative to said engine to camshaft phaser seal (114).
10. An internal combustion engine (10) as set in any of the claims 7 to 9 wherein said
camshaft support (18) defines a camshaft support bore (124) and said engine to camshaft
phaser seal (114) is located within said camshaft support bore (124).
11. An internal combustion engine (10) as set in claim 10 wherein said back cover (34)
includes a ring-shaped back cover sealing body (132) extending axially from said back
cover (34) into said camshaft support bore (124) such that said engine to camshaft
phaser seal (114) seals against said back cover sealing body (132).
12. An internal combustion engine (10) as set in any of the preceding claims wherein said
engine cover to camshaft phaser seal (112) is fixed to said actuator (46').
13. An internal combustion engine (10) as set in any of the preceding claims wherein said
actuator (46') includes an actuator seal bore (144) extending axially into said actuator
(46') and said engine cover to camshaft phaser seal (112) is fixed within said actuator
seal bore (144).