FIELD OF THE INVENTION
[0001] The invention pertains to the field of camshaft disposition within an internal combustion
engine. More particularly, the invention pertains to camshaft incorporating variable
camshaft timing (VCT) phaser rotor.
BACKGROUND OF THE INVENTION
[0002] The performance of an internal combustion engine can be improved by the use of dual
camshafts, one to operate the intake valves of the various cylinders of the engine
and the other to operate the exhaust valves. Typically, one of such camshafts is driven
by the crankshaft of the engine, through a sprocket and chain drive or a belt drive,
and the other of such camshafts is driven by the first, through a second sprocket
and chain drive or a second belt drive. Alternatively, both of the camshafts can be
driven by a single crankshaft powered chain drive or belt drive. Engine performance
in an engine with dual camshafts can be further improved, in terms of idle quality,
fuel economy, reduced emissions or increased torque, by changing the positional relationship
of one of the camshafts, usually the camshaft which operates the intake valves of
the engine, relative to the other camshaft and relative to the crankshaft, to thereby
vary the timing of the engine in terms of the operation of intake valves relative
to its exhaust valves or in terms of the operation of its valves relative to the position
of the crankshaft.
[0003] Consideration of information disclosed by the following U.S. Patents, which are all
hereby incorporated by reference, is useful when exploring the background of the present
invention.
[0004] U.S. Patent No. 5,002,023 describes a VCT system within the field of the invention
in which the system hydraulics includes a pair of oppositely acting hydraulic cylinders
with appropriate hydraulic flow elements to selectively transfer hydraulic fluid from
one of the cylinders to the other, or vice versa, to thereby advance or retard the
circumferential position on of a camshaft relative to a crankshaft. The control system
utilizes a control valve in which the exhaustion of hydraulic fluid from one or another
of the oppositely acting cylinders is permitted by moving a spool within the valve
one way or another from its centered or null position. The movement of the spool occurs
in response to an increase or decrease in control hydraulic pressure, P
c, on one end of the spool and the relationship between the hydraulic force on such
end and an oppositely direct mechanical force on the other end which results from
a compression spring that acts thereon.
[0005] U.S. Patent No. 5,107,804 describes an alternate type of VCT system within the field
of the invention in which the system hydraulics include a vane having lobes within
an enclosed housing which replace the oppositely acting cylinders disclosed by the
aforementioned U.S. Patent No. 5,002,023. The vane is oscillatable with respect to
the housing, with appropriate hydraulic flow elements to transfer hydraulic fluid
within the housing from one side of a lobe to the other, or vice versa, to thereby
oscillate the vane with respect to the housing in one direction or the other, an action
which is effective to advance or retard the position of the camshaft relative to the
crankshaft. The control system of this VCT system is identical to that divulged in
U.S. Patent No. 5,002,023, using the same type of spool valve responding to the same
type of forces acting thereon.
[0006] U.S. Patent Nos. 5,172,659 and 5,184,578 both address the problems of the aforementioned
types of VCT systems created by the attempt to balance the hydraulic force exerted
against one end of the spool and the mechanical force exerted against the other end.
The improved control system disclosed in both U.S. Patent Nos. 5,172,659 and 5,184,578
utilizes hydraulic force on both ends of the spool. The hydraulic force on one end
results from the directly applied hydraulic fluid from the engine oil gallery at full
hydraulic pressure, P
s. The hydraulic force on the other end of the spool results from a hydraulic cylinder
or other force multiplier which acts thereon in response to system hydraulic fluid
at reduced pressure, P
c, from a PWM solenoid. Because the force at each of the opposed ends of the spool
is hydraulic in origin, based on the same hydraulic fluid, changes in pressure or
viscosity of the hydraulic fluid will be self-negating, and will not affect the centered
or null position of the spool.
[0007] U.S. Patent No. 5,289,805 provides an improved VCT method which utilizes a hydraulic
PWM spool position control and an advanced control method suitable for computer implementation
that yields a prescribed set point tracking behavior with a high degree of robustness.
[0008] In U.S Patent No. 5,361,735, a camshaft has a vane secured to an end for non-oscillating
rotation. The camshaft also carries a timing belt driven pulley which can rotate with
the camshaft but which is oscillatable with respect to the camshaft. The vane has
opposed lobes which are received in opposed recesses, respectively, of the pulley.
The camshaft tends to change in reaction to torque pulses which it experiences during
its normal operation and it is permitted to advance or retard by selectively blocking
or permitting the flow of engine oil from the recesses by controlling the position
of a spool within a valve body of a control valve in response to a signal from an
engine control unit. The spool is urged in a given direction by rotary linear motion
translating means which is rotated by an electric motor, preferably of the stepper
motor type.
[0009] U.S. Patent No. 5,497,738 shows a control system which eliminates the hydraulic force
on one end of a spool resulting from directly applied hydraulic fluid from the engine
oil gallery at full hydraulic pressure, P
s, utilized by previous embodiments of the VCT system. The force on the other end of
the vented spool results from an electromechanical actuator, preferably of the variable
force solenoid type, which acts directly upon the vented spool in response to an electronic
signal issued from an engine control unit ("ECU") which monitors various engine parameters.
The ECU receives signals from sensors corresponding to camshaft and crankshaft positions
and utilizes this information to calculate a relative phase angle. A closed-loop feedback
system which corrects for any phase angle error is preferably employed. The use of
a variable force solenoid solves the problem of sluggish dynamic response. Such a
device can be designed to be as fast as the mechanical response of the spool valve,
and certainly much faster than the conventional (fully hydraulic) differential pressure
control system. The faster response allows the use of increased closed-loop gain,
making the system less sensitive to component tolerances and operating environment.
[0010] U.S. Patent No. 5,657,725 shows a control system which utilizes engine oil pressure
for actuation. The system includes a camshaft that has a vane secured to an end thereof
for non-oscillating rotation therewith. The camshaft also carries a housing which
can rotate with the camshaft but which is oscillatable with the camshaft. The vane
has opposed lobes which are received in opposed recesses, respectively, of the housing.
The recesses have greater circumferential extent than the lobes to permit the vane
and housing to oscillate with respect to one another, and thereby permit the camshaft
to change in phase relative to a crankshaft. The camshaft tends to change direction
in reaction to engine oil pressure and/or camshaft torque pulses which it experiences
during its normal operation, and it is permitted to either advance or retard by selectively
blocking or permitting the flow of engine oil through the return lines from the recesses
by controlling the position of a spool within a spool valve body in response to a
signal indicative of an engine operating condition from an engine control unit. The
spool is selectively positioned by controlling hydraulic loads on its opposed end
in response to a signal from an engine control unit. The vane can be biased to an
extreme position to provide a counteractive force to a unidirectionally acting frictional
torque experienced by the camshaft during rotation.
[0011] U.S. Patent No. 6,247,434 shows a multi-position variable camshaft timing system
actuated by engine oil. Within the system, a hub is secured to a camshaft for rotation
synchronous with the camshaft, and a housing circumscribes the hub and is rotatable
with the hub and the camshaft and is further oscillatable with respect to the hub
and the camshaft within a predetermined angle of rotation. Driving vanes are radially
disposed within the housing and cooperate with an external surface on the hub, while
driven vanes are radially disposed in the hub and cooperate with an internal surface
of the housing. A locking device, reactive to oil pressure, prevents relative motion
between the housing and the hub. A controlling device controls the oscillation of
the housing relative to the hub.
[0012] U.S. Patent No. 6,250,265 shows a variable valve timing system with actuator locking
for an internal combustion engine. The variable camshaft timing system is comprised
of a camshaft with a vane secured to the camshaft for rotation with the camshaft but
not for oscillation with respect to the camshaft. The vane has a circumferentially
extending plurality of lobes projecting radially outwardly therefrom and is surrounded
by an annular housing that has a corresponding plurality of recesses each of which
receives one of the lobes and has a circumferential extent greater than the circumferential
extent of the lobe received therein to permit oscillation of the housing relative
to the vane and the camshaft while the housing rotates with the camshaft and the vane.
Oscillation of the housing relative to the vane and the camshaft is actuated by pressurized
engine oil in each of the recesses on opposed sides of the lobe therein, the oil pressure
the recesses being preferably derived in part from a torque pulse in the camshaft
as it rotates during its operation. An annular locking plate is positioned coaxially
with the camshaft and the annular housing and is moveable relative to the annular
housing along a longitudinal central axis of the camshaft between a first position,
where the locking plate engages the annular housing to prevent its circumferential
movement relative to the vane and a second position where circumferential movement
of the annular housing relative to the vane is permitted. The locking plate is biased
by a spring toward its first position and is urged away from its first position toward
its second position by engine oil pressure, to which it is exposed by a passage leading
through the camshaft, when engine oil pressure is sufficiently high to overcome the
spring biasing force, which is the only time when it is desired to change the relative
positions of the annular housing and the vane. The movement of the locking plate is
controlled by an engine electronic control unit either through a closed loop control
system or an open loop control system.
[0013] U.S. Patent No. 6,263,846 shows a control valve strategy for vane-type variable camshaft
timing system. The strategy involves an internal combustion engine that includes a
camshaft and hub secured to the camshaft for rotation therewith, where a housing circumscribes
the hub and is rotatable with the hub and the camshaft, and is further oscillatable
with respect to the hub and camshaft. Driving vanes are radially inwardly disposed
in the housing and cooperate with the hub, while driven vanes are radially outwardly
disposed in the hub to cooperate with the housing and also circumferentially alternate
with the driving vanes to define circumferentially alternating advance and retard
chambers. A configuration for controlling the oscillation of the housing relative
to the hub includes an electronic engine control unit, and an advancing control valve
that is responsive to the electronic engine control unit and that regulates engine
oil pressure to and from the advance chambers. A retarding control valve responsive
to the electronic engine control unit regulates engine oil pressure to and from the
retard chambers. An advancing passage communicates engine oil pressure between the
advancing control valve and the advance chambers, while a retarding passage communicates
engine oil pressure between the retarding control valve and the retard chambers.
[0014] U.S. Patent No. 6,311,655 shows multi-position variable cam timing system having
a vane-mounted locking-piston device. An internal combustion engine having a camshaft
and variable camshaft timing system, wherein a rotor is secured to the camshaft and
is rotatable but non-oscillatable with respect to the camshaft is described. A housing
circumscribes the rotor and is rotatable with both the rotor and the camshaft. The
housing is further oscillatable with respect to both the rotor and the camshaft between
a fully retarded position and a fully advanced position. A locking configuration prevents
relative motion between the rotor and the housing, and is mounted within either the
rotor or the housing, and is respectively and releasably engageable with the other
of either the rotor and the housing in the fully retarded position, the fully advanced
position, and in positions therebetween. The locking device includes a locking piston
having keys terminating one end thereof, and serrations mounted opposite the keys
on the locking piston for interlocking the rotor to the housing. A controlling configuration
controls oscillation of the rotor relative to the housing.
[0015] U.S. Patent No. 6,374,787 shows a multi-position variable camshaft timing system
actuated by engine oil pressure. A hub is secured to a camshaft for rotation synchronous
with the camshaft, and a housing circumscribes the hub and is rotatable with the hub
and the camshaft and is further oscillatable with respect to the hub and the camshaft
within a predetermined angle of rotation. Driving vanes are radially disposed within
the housing and cooperate with an external surface on the hub, while driven vanes
are radially disposed in the hub and cooperate with an internal surface of the housing.
A locking device, reactive to oil pressure, prevents relative motion between the housing
and the hub. A controlling device controls the oscillation of the housing relative
to the hub.
[0016] U.S. Patent No. 6,477,999 shows a camshaft that has a vane secured to an end thereof
for non-oscillating rotation therewith. The camshaft also carries a sprocket that
can rotate with the camshaft but is oscillatable with respect to the camshaft. The
vane has opposed lobes that are received in opposed recesses, respectively, of the
sprocket. The recesses have greater circumferential extent than the lobes to permit
the vane and sprocket to oscillate with respect to one another. The camshaft phase
tends to change in reaction to pulses that it experiences during its normal operation,
and it is permitted to change only in a given direction, either to advance or retard,
by selectively blocking or permitting the flow of pressurized hydraulic fluid, preferably
engine oil, from the recesses by controlling the position of a spool within a valve
body of a control valve. The sprocket has a passage extending therethrough the passage
extending parallel to and being spaced from a longitudinal axis of rotation of the
camshaft. A pin is slidable within the passage and is resiliently urged by a spring
to a position where a free end of the pin projects beyond the passage. The vane carries
a plate with a pocket, which is aligned with the passage in a predetermined sprocket
to camshaft orientation. The pocket receives hydraulic fluid, and when the fluid pressure
is at its normal operating level, there will be sufficient pressure within the pocket
to keep the free end of the pin from entering the pocket. At low levels of hydraulic
pressure, however, the free end of the pin will enter the pocket and latch the camshaft
and the sprocket together in a predetermined orientation.
[0017] In some VCT systems, a phaser having a rotor needs to be rigidly affixed to a camshaft
and angularly adjustable in relation to other parts of the phaser.
[0018] Referring to Fig. 1, an exploded view of a prior art VCT device or phaser is depicted.
A rotor 1 is fixedly positioned on the camshaft 9, by means of mounting flange 8,
to which it and rotor front plate 4 is fastened by screws 14. The rotor 1 has a diametrically
opposed pair of radially outwardly projecting vanes 16, which fit into recesses 17
in the housing body 2. The inner plate 5, housing body 2, and outer plate 3 are fastened
together around the mounting flange 8, rotor 1 and rotor front plate 4 by screws 13,
so that the recesses 17 holding the vanes 16, enclosed by outer plate 3 and inner
plate 5, form fluid-tight chambers. The timing gear 11 is connected to the inner plate
5 by screws 12. Collectively, the inner plate 5, housing body 2, outer plate 3 and
timing gear 11 will be referred to herein as the "housing".
[0019] Japanese Patent publication number 04209912(A), entitled: "Valve System Of Engine"
teaches an improved apparatus having a simplified structure with improved supporting
rigidity by holding the hub of a variable valve timing mechanism on a camshaft end
part by a means of a cylindrical shaft member to fasten the hub by means of a fastening
member, and bearing-supporting the shaft member on a cylinder head.
[0020] The use of a hub on a variable valve timing mechanism to fasten the same onto a camshaft
is known. Japanese Patent 04209912 (A) teaches a simplified structure having improved
supporting rigidity by holding the hub of a variable valve timing mechanism on a camshaft
end part by a means of a cylindrical shaft member to fasten the hub by means of a
fastening member, and bearing-supporting the shaft member on a cylinder head. The
structure of the device is as follows. In a V typed engine 1 provided with a DOHC
valve system, gears 7, 8 provided between cams are arranged on respective one end
parts of an intake side camshaft 2 and an exhaust side camshaft 3 so as to engage
each other as a driving wheel provided between the cams. A variable valve timing mechanism
20 is arranged inside the boss part 7a of the gear 7 provided between the cams of
the intake side. A cylindrical shaft member 17a for holding the hub 21 of the variable
valve timing mechanism 20 is provided on the center part of the gear 7 provided between
the cams of the intake side, and the shaft member 17 is installed by a jointing member
18 jointed on the camshaft 2. The journal part 17a of the shaft member 17 is bearing-supported
on a front end bearing part 5a mounted in the forward of the gear chamber 9 of a cylinder
head 4.
[0021] The use of brazing in forming a camshaft is known. Japanese Patent 60021195 (A) teaches
a device that has a joined camshaft consisting of joint members and a shaft member
joined to the strength equivalent to the strength of the base metal by subjecting
the shaft part of the camshaft consisting of a steel material and fitting members
such as cam members, journal members, etc. formed of a cast iron to join by copper
brazing in a furnace. The device includes a shaft part 2 consisting of a hollow or
solid steel material and separately manufactured fitting members made of a cast iron
such as cam members 4, journal members 5, etc. are disposed in prescribed positions
and are joined under the following conditions: The shaft part 2 and the above-described
fitting members are joined by brazing in a furnace for ≥15min in a temp. range of
1,090W1,150°C non- oxidizing atmosphere. It is necessary in this case to maintain
the hardness of the cast iron fitting members within a 130W320Hv range. The joint
strength between the fitting members and the shaft member is thus made equivalent
to or higher than the strength of the base metal. However, no rotor of a VCT phaser
is involved herein.
[0022] The forming of cam lobes by means of swaging is known. European patent EP0313985B1
teaches a method of making a camshaft from a blank having a cam shape, the configuration
of the camshaft with the cams and the bearings being moulded into the blank by swaging
and circular kneading by means of tool segments which at least partially surround
the blank and exert radial compressive forces thereon and thus alter the shape and
the cross section of the blank, characterized in that, in a first step, the cam-shaped
blank is given an at least approximately circular shape by preforming by means of
forging or hammering in the region of the bearings of the camshaft, and that subsequently,
in a second step, the configuration of the camshaft with the cams and the bearings
is molded by swaging and circular kneading by means of tool elements which at least
partially surround the blank and exert radial compressive forces thereon and thus
alter its shape and cross section both in the region of the bearings and in the remaining
regions of the camshaft. However, no rotor of a VCT phaser is involved herein.
[0023] However, in virtually all VCT technology applications, the VCT units such as a phaser
need to be downsized in order to reduce packaging requirements. The form factor that
limits the axial and radial package of a VCT needs to be suitably reduced. Further,
the use of a more permanent means of affixing the rotor of a phaser to the camshaft
will allow for reduction in the radial packaging requirements.
[0024] Typically in a VCT assembly, a pilot is needed for locating the VCT system. Additional
fasteners are required in the assembly; elaborate hydraulic seals are required for
the rotor, camshaft. in addition, the cam lobe are separated into independent pieces.
As can be seen, the separated and independent nature of the assembly necessarily entails
mounting of the same and its concomitant adjustments. Therefore, it is desirable to
have a single piece rotor-camshaft-cam lobe assembly.
SUMMARY OF THE INVENTION
[0025] In a VCT device, a single piece rotor-cam shaft-cam lobe assembly is provided.
[0026] In a VCT device, an actuator, instead of being placed at the rotor end of the single
piece rotor-cam shaft-cam lobe member, is placed at the opposite end.
[0027] A VCT device, which provides a rotor that is machined out of a single piece of material
in which camshaft and cam lobe are also formed thereon.
[0028] In a VCT device, alignment of bearing surfaces is improved in that no inter-member
alignment of bearing surface is involved for the present single piece rotor-cam shaft-cam
lobe member.
[0029] In a VCT device of a motor cycle engine, the extra space taken by the actuator is
eliminated by having the same placed at the opposite end of the camshaft.
[0030] In a VCT device, a back plate having a cam shaped inner opening is provided for facilitating
its mounting of the backing plate.
[0031] In a VCT device, permanent means of affixing part of the VCT device onto a shaft
is provided.
[0032] In a VCT device, a set of non-reversible means of affixing part of the VCT device
onto a shaft is provided.
[0033] In VCT systems, the rotor of a phaser is permanently, non-reversibly affixed onto
a camshaft.
[0034] A VCT device having reduced form factors are provided. The reduced form factors include
axial reduction and radial reduction.
[0035] A VCT device free from area on its frontal face for receiving connecting members
such as bolt or screws is provided.
[0036] Accordingly, a device is provided, which includes: a first end having a rotor with
a hollow space positioned at the center disposed to rotate relative to a housing;
and a rotating shaft, integral to the rotor, having a plurality of lobes thereon terminating
to a second end, the rotating shaft being made of the same material as the rotor.
[0037] Accordingly, a VCT system is provided. The system includes: a phaser having a housing
and a rotor; and a device. The device includes: a first end having the rotor with
a hollow space positioned at the center disposed to rotate relative to the housing;
and a rotating shaft, integral to the rotor, having a plurality of lobes thereon terminating
to a second end, the rotating shaft being made of the same material as the rotor.
BRIEF DESCRIPTION OF THE DRAWING
[0038]
Fig. 1 shows an exploded view of a prior art VCT device.
Fig. 2 shows a frontal view of a prior art rotor.
Fig. 2A shows a frontal view of the rotor of the present invention.
Fig. 3 shows a first perspective view of the preferred embodiment of the present invention.
Fig. 4 shows a second perspective view of the preferred embodiment of the present
invention.
Fig. 5 shows an alternative embodiment of the present invention.
Fig. 6 shows a more detailed blow up view of the single piece rotor-cam shaft-cam
lobe member of Fig. 5.
Fig. 7 shows a perspective view of the single piece rotor-cam shaft-cam lobe member
of Fig. 5.
Fig. 8 shows a sectional view of the single piece rotor-cam shaft-cam lobe member
of Fig. 5.
Fig. 9 shows an alternative of single piece rotor-cam shaft-cam lobe member of Fig.
5.
Fig. 10 shows a first means of connection of the present invention.
Fig.11 shows a second means of connection of the present invention.
Fig.12 shows a third means of connection of the present invention.
Fig. 13 shows a fourth means of connection of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0039] It is desirable to suitably shorten the axial length of a VCT device such as a phaser
by eliminating mounting flange 8 that is mounted onto a shaft such as the camshaft
9. As can be seen, by eliminating flange 8, the axial length of the VCT device is
shortened in that some axial dimensional contribution in length of flange 8 is reduced.
Flange 8 has openings or holes for accommodating or receiving connecting members such
as screws 14 for connecting portions of the phaser such as the rotor 1 onto camshaft
9. New means for connecting portions of the phaser such as the rotor 1 onto camshaft
9 is disclosed infra. Further, it is desirable to suitably reduce dimensionally the
radial size of the VCT device by eliminating fasteners such as screws 14. Thereby
region 18 can be eliminated. By eliminating region 18, the radial dimension of the
VCT device can be reduced.
[0040] Referring to Fig. 2, frontal view 10 of a prior art rotor is shown. In the present
figure, three lobes 16 are shown. All the rest of the features and parts herein the
present figure are substantially similar to that of Fig. 1. A region 18 is provided
for accommodating the screws 14. Region 18 is limited by two concentric circles (in
broken line) having a common center. Openings 14a are distributed within region 18
for allowing the screws 14 to pass through for fastening purposes. For example, as
shown in Fig. 1, screws 14 transpose through rotor 1 and fasten themselves onto flange
8.
[0041] Referring to Fig. 2A, a frontal face view 10a of the rotor 1a of the present invention
is shown. Frontal view 10a is substantially identical to frontal view 10 of Fig. 2
except that region 18 is eliminated. As can be appreciated, the elimination of region
18 causes a reduction of radial dimension of rotor 1a in that the area of the front
face of rotor 1a is smaller as compared with that of the rotor 1 of Figs 1 and 2.
[0042] Vanes 16 are provided that may have similar or different size as that of Fig. 2.
Further, the number of vanes 16 per rotor 1a may be any natural number or positive
integer. In addition, an opening 19 is provided for the coupling of rotor 1a with
a shaft such as camshaft 9 of Fig. 1.
[0043] Figs. 3 and 4 depict perspective views of the present invention. Referring to Fig.
3, a first perspective view of the VCT device, in part, is shown. The VCT device comprises
rotor 1a which constitutes part of a phaser. Rotor 1a has opening 19 formed substantially
at the center of rotor 1a. Rotor 1a is connected to a first end of the camshaft 9,
which has cam lobes 22 at a distance to the first end respectively. Rotor 1a is connected
to camshaft 9 without the use of screws 14 and the flange 8 of the prior art phaser
device shown in Figs. 1 and 2. The rotor 1a and camshaft 9 are connected together
in a non-reversible means described infra. As can be seen, the functional portion
of what is indicated as flange 8 in Fig. 1 is now incorporated in the camshaft/phaser
component in Figs 3 and 4.
[0044] Referring to Fig. 4, a second perspective view of the VCT device of Fig. 3 is shown.
Note that flange 8 of Fig. 1 or other interposing members of prior art is eliminated.
Therefore, the axial length of the device along the length of camshaft 9 is shortened.
[0045] Referring to Fig. 5, an alternative embodiment of the present invention is shown.
A camshaft 9a and a rotor 1b are integrally connected together. Rotor 1b has slots
26 disposed to receive vanes (not shown) preferably made of steel. In other words,
the vanes, instead of formed as an extension of the rotor or formed integrally with
the rotor, the vanes are separate parts that needs to be inserted into slots 26 in
the rotor 1b.
[0046] Referring to Figs 6-9, a detailed description of single piece rotor-cam shaft-cam
lobe assembly of the present invention is shown.
[0047] Referring to Fig. 6, a more detailed blow up view of a single piece rotor-cam shaft-cam
lobe member 38 is shown. In single piece rotor-cam shaft-cam lobe member 38, cam lobes
22, camshaft 9a, and rotor 1b are formed out of a single piece or member. For example,
single piece rotor-cam shaft-cam lobe member 38 is machined out of a single metal
or alloy piece. Slots 26 are located on the outer circumference of rotor 1b for the
accommodation of vanes 40 having vane springs 42 interposed therebetween. Vanes 40
are disposed to oscillate within cavities 43 formed within sprocket housing 44. A
check valve 46 is provided within rotor 1b for controlling control fluid flowing unidirectionally
within a passage, wherein a segment of which is formed within the single piece rotor-cam
shaft-cam lobe member 38. A lock pin 48 is provided for locking sprocket housing 44
and rotor 1b into a fixed angular relationship. An accompanying spring pin 49 and
lock pin spring 50 are provided for coupling to lock pin 48. A sleeve 52 having a
sleeve slot 54 is disposed to fit in the opening 19. A backing plate 56 is provided
to cover the back portion of the rotor 1b and sprocket housing 44 unit to contain
control fluid within the VCT system. Backing plate 56 has a cam shaped inner openings
57 for allowing the same to traverse through the cam lobes 22 before reaching the
desired location for the final assembly.
[0048] Referring to Fig. 7, a perspective view of the VCT assembly is shown. The single
piece rotor-cam shaft-cam lobe member 38 including camshaft 9a, rotor 1b, and cam
lobes 22 are shown. At the rotor 1b end of single piece rotor-cam shaft-cam lobe member
38, sprocket housing 44 is disposed to be engagable with single piece rotor-cam shaft-cam
lobe member 38 for adjusting an angular relationship. Lock pin 48 with its accompanying
lock pin spring 50 are disposed to be positioned in sprocket housing 44 as shown for
stopping or rigidly fixing an angular relationship of the phaser assembly. Pulse wheel
58 is provided to be coupled to the sprocket housing 44 as shown. Pulse wheel 58 includes
teeth 59 for generating pulses as wheel 58 turns. A retaining element 60 is disposed
about the center of pulse wheel 58 for fitting in the sleeve slot 54 of sleeve 52.
[0049] Referring to Fig. 8, a sectional view of the VCT assembly is shown. Note that single
piece rotor-cam shaft-cam lobe member 38 that comprises rotor 1b, camshaft 9a, and
cam lobes 22 are formed out of a single piece of material. Single piece rotor-cam
shaft-cam lobe member 38 may be made out of a single piece machined alloy material.
Spool valve 62 is substantially disposed within the rotor 1b portion of single piece
rotor-cam shaft-cam lobe member 38 and having spool spring 64 placed at the inner
end of sleeve 52. Control fluid passages 66 are formed within single piece rotor-cam
shaft-cam lobe member 38 for facilitating the controlled flow of control fluid flowing
therein. Sprocket housing 44 and backing plate 56 are mounted on the VCT assembly
as shown.
[0050] Referring to Fig. 9, an alternative of the present invention is shown. In this alternative
embodiment, actuator 70, instead of being placed at the rotor 1b end of the single
piece rotor-cam shaft-cam lobe member 38, is place at the opposite end. A hollow tube
72 is formed within the single piece rotor-cam shaft-cam lobe member 38 for accommodating
a set of force transmitting members in the transmission of force from actuator 70
to spool valve 62 and then to spool spring 64 which is anchored on a seat (not shown).
This causes the displacement of spool valve 62 in which controlled fluid are controlled
in such a way that an angular relationship is adjusted or maintained. The set of force
transmitting members comprises a first ball joint 74a, a second ball joint 74b, a
first force transmitting segment 76a, a second force transmitting segment 76b, and
a third force transmitting segment 76c. The spool valve 62 and spool spring 64 are
placed within sleeve 52. Control fluid pressure is maintained within the hollow tube
72. There exits a balancing force with the hollow tube 72 as a result of control fluid
pressure therein. Further the hollow tube nature of hollow tube 72 necessarily reduces
the mass of single piece rotor-cam shaft-cam lobe member 38. Further, because of the
hollow nature of hollow tube 72, single piece rotor-cam shaft-cam lobe member 38 may
be made of materials of higher stiffness than a non-hollow member. In addition, actuator
70 may be a type of solenoid such as variable force solenoid (VFS). One advantage
of placing actuator 70 on the on the opposite side as shown herein is that for a two
cylinder motor cycle engine, the extra space taken by the actuator 70 may impede the
operation and comfort of the vehicle driver.
[0051] As can be seen, the present invention may provide a rotor that is machined out of
a single piece of material in which camshaft and cam lobe are also formed thereon.
This way, the alignment of bearing surfaces is improved in that no inter-member alignment
of bearing surface is involved for the present single piece rotor-cam shaft-cam lobe
member 38. Further, the load capability of the bearings is improved as well. For example,
the rotor 1b sprocket housing 44 bearing surface is improved in that no flange is
required. In addition, check valve 46 may be placed within the single piece rotor-cam
shaft-cam lobe member 38 assembly including the camshaft 9a. Also note that cam shaped
inner opening 57 of backing plate 56 possesses a unique shape for facilitating its
mounting in that cam lobes 22 need to be traversed before the eventual mounting of
backing plate 56.
[0052] In addition, some features such as check valves seats, etc. may be machined integral
onto the face of the rotor 1b or other portions of rotor-cam shaft-cam lobe member
38. Furthermore, the number of cam lobes is not limited to two.
[0053] By way of an example, the present invention teaches method and apparatus to apply
VCT technology to desired applications such as connecting parts of a phaser on a first
end of a camshaft. The relevant size of units such as rotor 1a size must be downsized
in order to reduce packaging requirements. One factor that limits the axial and radial
package of prior art product is the bolt circle diameter that affixes the phaser rotor
to the end of the camshaft. In other words, region 18 of Fig. 2 affects or increases
the dimension of a phaser, camshaft combination device. Further, the use of a more
permanent means of affixing the rotor to the camshaft is desirable in that a reduction
in the radial packaging requirements is achieved. The permanent means can be a non-reversible
way to affix rotor 1a onto camshaft 9 in that once the two pieces, rotor 1a or rotor
1b and camshaft 9, are rigidly affixed to each other; the end product is generally
a fixed thing in that taking the thing apart once they are rigidly affixed onto each
other tends to render the whole thing useless. By way of a counter example, the prior
art uses screws 14 (in Fig. 1) for non-permanently affixing rotor 1 onto camshaft
9, which is undesirable in that area 18 and flange 8 are required. Area 18 and flange
8 are undesirable because they increase the dimension of an end product such as the
phaser. The dimension increases include both an axial increase via the introduction
of flange 8, and the radial increase via the introduction of area 18. The present
invention teaches the reduction of both the axial dimension and the radial dimension
of a VCT device by eliminating both the flange 8 and area 18. As radial package space
is reduced, the phaser components can then be pulled under the sprocket which also
reduces the required axial package space. The bearing surface for the sprocket would
also be incorporated into the end of the camshaft.
[0054] The rotor and bearing surface could be affixed onto the end of the camshaft in a
number of ways. The means of affixing the rotor to the end of the camshaft would include
but not be limited to the following 5 scenarios.
1 PRESSING THE ROTOR ONTO A STRAIGHT HUB
[0055] By pressing the rotor onto a straight hub at one end of camshaft, rotor such as rotor
1a or rotor 1b may be permanently affixed onto camshaft 9. As can be seen, no extra
connecting members such as screw 14 or flange 8 is needed herein. By way of an example,
camshaft 9 may have one end 30 disposed to be fitted into opening 19 of rotor 1a as
shown in Fig. 10.
[0056] Hub is referred to as a cylindrical projection on the end of the camshaft onto which
the inner diameter of the phaser is pressed. As shown in Fig. 10, the region around
end 30 is a hub.
2. PRESSING THE ROTOR ONTO A HUB USING A STRAIGHT SPLINE ON ONE COMPONENT AND A HELICAL
SPLINE ON THE SECOND COMPONENT
[0057] This second means of irreversible connection is similar to the first means in that
the rotor is pressed upon a hub of a camshaft. The difference is that one component
such as the rotor may have an opening 19, wherein an inside surface of opening 19
of the rotor 1a may be lined with straight spline. Whereas another component such
as the camshaft 9 may have one end 30a may have a non-straight spline such as a helical
spline. By way of an example, as shown in Fig. 11, by pressing the rotor 1a onto a
hub using a straight spline 32 and a helical spline 34 on the one end 30a.
3. BRAZING THE ROTOR ONTO THE CAMSHAFT
[0058] Brazing the rotor onto the camshaft is another means to irreversibly affix the rotor
such as rotor 1a onto a camshaft 9. Any known means of brazing is contemplated by
the present invention.
4. SWAGING THE ROTOR ONTO THE CAMSHAFT
[0059] Rotor can also be swaged onto the camshaft. For example, referring to Fig. 12, by
swaging the rotor 1a onto a first end 30b of the camshaft 9, the irreversible connection
of rotor and camshaft is achieved. First end 30b, which may or may not have an internal
opening 19a is first inserted or placed into opening 19 of the rotor 1a.
[0060] As can be appreciated, swaging is a process that is used to reduce or increase the
diameter of tubes or rods such as a camshaft. Swaging may be done by placing camshaft
9 inside a die that applies compressive force by hammering radially. In addition,
swaging can be achieved by placing a mandrel inside the internal opening 19a and applying
radial compressive forces on the outer diameter. As can be appreciated, the inner
diameter can be a different shape, for example the internal opening 19a may be a hexagon,
and the resultant outer diameter after swaging can still be substantially circular.
[0061] To apply swaging, the existence of internal opening 19a is helpful, but not necessary.
The net result is to permanently or irreversibly affix the rotor and the camshaft.
5. BALLIZING THE ROTOR ONTO THE CAMSHAFT WHERE THE CAMSHAFT IS A HOLLOW COMPONENT
[0062] Referring to Fig. 13, wherein the camshaft is formed such that opening 19a transcend
or is formed throughout the camshaft structure, ballizing may be a means of permanently
or irreversibly affixing rotor 1a onto camshaft 9. Initially, shaft 9 is place within
rotor 1a such that a first end 30c of camshaft 9 is within opening 19 of the rotor
1a. A ball 32 made of materials such as a tungsten carbide speeds through opening
19a of camshaft 9 at a desired speed along a direct such as direction 34. Note that
the direction of travel for ball 32 may be the reverse of direction 34. In other words,
the direction of travel may be 180 degrees of direction 34. Therefore, by ballizing
the rotor onto the camshaft where the camshaft is a hollow component, the net result
is achieved in that the rotor and the camshaft is permanently or irreversibly affixed
together.
[0063] Alternatively, the rotor and bearing surface may also be machined as part of the
camshaft itself. Fig. 5 depicts such an alternative. In other words, a single member
can include a rotor, a bearing surface, and a camshaft. It is noted that in some cases,
the camshaft can be considered an extension of the phaser. Or the camshaft may be
considered as an extension of the rotor. This is especially true in cases wherein
less cam lobes are involved. Therefore, it necessarily is more convenient to machine
the rotor and the camshaft out of one piece of material. It is further noted that
cam lobe may not be machined out of one piece of material.
[0064] It is noted that in the preferred embodiment, the rotor is connected to a camshaft.
However, the present invention contemplates the coupling or connecting of the rotor
of a phaser onto any driving or driven shaft. For example, the rotor may be coupled
to a crank shaft, or to any camshaft whether the camshaft is a driving or driven shaft.
[0065] The following are terms and concepts relating to the present invention.
[0066] It is noted the hydraulic fluid or fluid referred to supra are actuating fluids.
Actuating fluid is the fluid which moves the vanes in a vane phaser. Typically the
actuating fluid includes engine oil, but could be other hydraulic fluid. The VCT system
of the present invention may be a Cam Torque Actuated (CTA)VCT system in which a VCT
system that uses torque reversals in camshaft caused by the forces of opening and
closing engine valves to move the vane. The control valve in a CTA system allows fluid
flow from advance chamber to retard chamber, allowing vane to move, or stops flow,
locking vane in position. The CTA phaser may also have oil input to make up for losses
due to leakage, but does not use engine oil pressure to move phaser. Vane is a radial
element actuating fluid acts upon, housed in chamber. A vane phaser is a phaser which
is actuated by vanes moving in chambers.
[0067] There may be one or more camshaft per engine. The camshaft may be driven by a belt
or chain or gears or another camshaft. Lobes may exist on camshaft to push on valves.
In a multiple camshaft engine, most often has one shaft for exhaust valves, one shaft
for intake valves. A "V" type engine usually has two camshafts (one for each bank)
or four (intake and exhaust for each bank).
[0068] Chamber is defined as a space within which vane rotates. Chamber may be divided into
advance chamber (makes valves open sooner relative to crankshaft) and retard chamber
(makes valves open later relative to crankshaft). Check valve is defined as a valve
which permits fluid flow in only one direction. A closed loop is defined as a control
system which changes one characteristic in response to another, then checks to see
if the change was made correctly and adjusts the action to achieve the desired result
(e.g. moves a valve to change phaser position in response to a command from the ECU,
then checks the actual phaser position and moves valve again to correct position).
Control valve is a valve which controls flow of fluid to phaser. The control valve
may exist within the phaser in CTA system. Control valve may be actuated by oil pressure
or solenoid. Crankshaft takes power from pistons and drives transmission and camshaft.
Spool valve is defined as the control valve of spool type. Typically the spool rides
in bore, connects one passage to another. Most often the spool is located on center
axis of rotor of a phaser.
[0069] Differential Pressure Control System (DPCS) is a system for moving a spool valve,
which uses actuating fluid pressure on each end of the spool. One end of the spool
is larger than the other, and fluid on that end is controlled (usually by a Pulse
Width Modulated (PWM) valve on the oil pressure), full supply pressure is supplied
to the other end of the spool (hence
differential pressure). Valve Control Unit (VCU) is a control circuitry for controlling the VCT
system. Typically the VCU acts in response to commands from ECU.
[0070] Driven shaft is any shaft which receives power (in VCT, most often camshaft). Driving
shaft is any shaft which supplies power (in VCT, most often crankshaft, but could
drive one camshaft from another camshaft). ECU is Engine Control Unit that is the
car's computer. Engine Oil is the oil used to lubricate engine, pressure can be tapped
to actuate phaser through control valve.
[0071] Housing is defined as the outer part of phaser with chambers. The outside of housing
can be pulley (for timing belt), sprocket (for timing chain) or gear (for timing gear).
Hydraulic fluid is any special kind of oil used in hydraulic cylinders, similar to
brake fluid or power steering fluid. Hydraulic fluid is not necessarily the same as
engine oil. Typically the present invention uses "actuating fluid". Lock pin is disposed
to lock a phaser in position. Usually lock pin is used when oil pressure is too low
to hold phaser, as during engine start or shutdown.
[0072] Oil Pressure Actuated (OPA) VCT system uses a conventional phaser, where engine oil
pressure is applied to one side of the vane or the other to move the vane.
[0073] Open loop is used in a control system which changes one characteristic in response
to another (say, moves a valve in response to a command from the ECU) without feedback
to confirm the action.
[0074] Phase is defined as the relative angular position of camshaft and crankshaft (or
camshaft and another camshaft, if phaser is driven by another cam). A phaser is defined
as the entire part which mounts to cam. The phaser is typically made up of rotor and
housing and possibly spool valve and check valves. A piston phaser is a phaser actuated
by pistons in cylinders of an internal combustion engine. Rotor is the inner part
of the phaser, which is attached to a camshaft.
[0075] Pulse-width Modulation (PWM) provides a varying force or pressure by changing the
timing of on/off pulses of current or fluid pressure. Solenoid is an electrical actuator
which uses electrical current flowing in coil to move a mechanical arm. Variable force
solenoid (VFS) is a solenoid whose actuating force can be varied, usually by PWM of
supply current. VFS is opposed to an on/off (all or nothing) solenoid.
[0076] Sprocket is a member used with chains such as engine timing chains. Timing is defined
as the relationship between the time a piston reaches a defined position (usually
top dead center (TDC)) and the time something else happens. For example, in VCT or
VVT systems, timing usually relates to when a valve opens or closes. Ignition timing
relates to when the spark plug fires.
[0077] Torsion Assist (TA)or Torque Assisted phaser is a variation on the OPA phaser, which
adds a check valve in the oil supply line (i.e. a single check valve embodiment) or
a check valve in the supply line to each chamber (i.e. two check valve embodiment).
The check valve blocks oil pressure pulses due to torque reversals from propagating
back into the oil system, and stop the vane from moving backward due to torque reversals.
In the TA system, motion of the vane due to forward torque effects is permitted; hence
the expression "torsion assist" is used. Graph of vane movement is step function.
[0078] VCT system includes a phaser, control valve(s), control valve actuator(s) and control
circuitry. Variable Cam Timing (VCT) is a process, not a thing, that refers to controlling
and/or varying the angular relationship (phase) between one or more camshafts, which
drive the engine's intake and/or exhaust valves. The angular relationship also includes
phase relationship between cam and the crankshafts, in which the crank shaft is connected
to the pistons.
[0079] Variable Valve Timing (VVT) is any process which changes the valve timing. VVT could
be associated with VCT, or could be achieved by varying the shape of the cam or the
relationship of cam lobes to cam or valve actuators to cam or valves, or by individually
controlling the valves themselves using electrical or hydraulic actuators. In other
words, all VCT is VVT, but not all VVT is VCT.
[0080] Accordingly, it is to be understood that the embodiments of the invention herein
described are merely illustrative of the application of the principles of the invention.
Reference herein to details of the illustrated embodiments are not intended to limit
the scope of the claims, which themselves recite those features regarded as essential
to the invention.
1. A device, comprising:
a first end having a rotor (1b) with a hollow space (19) positioned at the center
disposed to rotate relative to a housing (44); and
a rotating shaft (9a), integral to the rotor (1b), having a plurality of lobes(22)
thereon and terminating to a second end, the rotating shaft (9a) being made of the
same material as the rotor (1b).
2. The device of claim 1 further comprising at least one separate vane (40) for affixing
onto a notch (26) on the outer circumference of the rotor (1b).
3. The device of claim 1 or 2, further comprising a back plate (56) disposed to be attached
to the backside of the rotor (1b) having a lobe shaped opening (57) for facilitating
the plate (56) to traverse past the plurality of lobes (22).
4. The device of claim 1, 2 or 3, wherein the rotor (1b) and the shaft (9a) are machined
out of a single piece member (38).
5. The device of any one of claims 1 to 4, wherein the plurality of lobes (22) are made
of the same material as the shaft (9a).
6. The device of claim 1, 2 or 3, wherein the device is machined out of a single piece
member resulting in having the rotor (1b), the shaft (9a), and the plurality of lobes
(22) thereon.
7. The device of any one of claims 1 to 6, wherein the hollow space (19) is disposed
to accommodate a control valve (62) for controlling the flow of a controlling liquid.
8. The device of any one of claims 1 to 7, wherein an actuator (70) is disposed to engage
a control valve (62) in the hollow space (19) of the rotor (1b) at the second end
via an opening thereon via a hollowed space (72) within the rotating shaft (9a).
9. The device of any one of claims 1 to 8, wherein an actuator (70) is disposed to engage
a control valve in the hollow space (19) of the rotor (1b) at the first end.
10. The device of any one of claims 1 to 9, wherein the device is a phaser.
11. The device of any one of claims 1 to 10, wherein the rotating shaft (9a) is a camshaft.
12. A VCT system comprising:
a phaser having a housing (2, 44) and a rotor (1, 1a, 1b); the rotor being included
in a device as claimed in any one of claims 1 to 9.
13. In a VCT system having a phaser coupled to a shaft (9, 9a), which can be a driving
or driven shaft, an arrangement wherein:
a rotor (1a) of the phaser is irreversibly connected to one end of the shaft (9) and
free of any region (18) having openings (14a) for accommodating independent fastening
members (14) such as screws, whereby the axial and radial dimension of the apparatus
is reduced.
14. A method for coupling part of a VCT device to a shaft (9), comprising the steps of:
providing a phaser having a rotor (1)rotating in relation to an opposite part of the
phaser (2), wherein the phaser is axially reduced by eliminating at least one part
(18) of the phaser; and
irreversibly, connecting the rotor (1) to the shaft (9).
15. The arrangement of claim 13 or method of claim 15, wherein the rotor (1) is irreversibly
connected to one end of the shaft (9) by pressing the rotor (1) onto a straight hub
(30); pressing the rotor (1) onto a hub using a straight spline (32) on an inside
surface of the rotor and a helical spline (30a) on a corresponding surface of the
shaft or vice versa; brazing the rotor onto the shaft (9); swaging the rotor onto
the shaft; or ballizing the rotor (1) onto the shaft where the shaft is a hollow component.
16. The arrangement of claim 13 or method of claim 14, wherein the rotor (1) is machined
as part of the shaft (9).