Multi-position variable camshaft timing system actuated by engine oil

Information

  • Patent Grant
  • 6247434
  • Patent Number
    6,247,434
  • Date Filed
    Tuesday, December 28, 1999
    24 years ago
  • Date Issued
    Tuesday, June 19, 2001
    23 years ago
Abstract
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 predetennined 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.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention generally relates to an internal combustion engine having a hydraulic control system for controlling the operation of a variable camshaft timing (VCT) system of the type in which the position of the camshaft is circumferentially varied relative to the position of a crankshaft in reaction to engine oil pressure. In such a VCT system, an electro-hydraulic control system is provided to effect the repositioning of the camshaft and a locking system is provided to selectively permit or prevent the electrohydraulic control system from effecting such repositioning.




More specifically, this invention relates to a multi-position VCT system actuated by engine oil pressure and having a large number of thin, spring-biased vanes defining alternating fluid chambers therein.




2. Description of the Prior Art




It is known that 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. It is also known that the performance of an internal combustion engine having dual camshafts, or but a single camshaft, can be improved by changing the positional relationship of a camshaft relative to the crankshaft.




It is also known that engine performance in an engine having one or more camshafts can be improved, specifically in terms of idle quality, fuel economy, reduced emissions, or increased torque. For example, the camshaft can be “retarded” for delayed closing of intake valves at idle for stability purposes and at high engine speed for enhanced output. Likewise, the camshaft can be “advanced” for premature closing of intake valves during mid-range operation to achieve higher volumetric efficiency with correspondingly higher levels of torque. In a dual-camshaft engine, retarding or advancing the camshaft is accomplished by changing the positional relationship of one of the camshafts, usually the camshaft that operates the intake valves of the engine, relative to the other camshaft and the crankshaft. Accordingly, retarding or advancing the camshaft varies the timing of the engine in tenes of the operation of the intake valves relative to the exhaust valves, or in terms of the operation of the valves relative to the position of the crankshaft.




Heretofore, many VCT systems incorporated hydraulics including an oscillatable vane having opposed lobes and being secured to a camshaft within an enclosed housing. Such a VCT system often includes fluid circuits having check valves, a spool valve and springs, and electromechanical valves to transfer fluid within the housing from one side of a vane lobe to the other, or vice versa, to thereby oscillate the vane with respect to the housing in one direction or the other. Such oscillation is effective to advance or retard the position of the camshaft relative to the crankshaft. These VCT systems are typically “self-powered” and have a hydraulic system actuated in response to torque pulses flowing through the camshaft.




Unfortunately, the above VCT systems may have several drawbacks. One drawback with such VCT systems is the requirement of the set of check valves and the spool valve. The check valves are necessary to prevent back flow of oil pressure during periods of torque pulses from the camshaft. The spool valve is necessary to redirect flow from one fluid chamber to another within the housing. Using these valves involves many expensive high precision parts that further necessitate expensive precision machining of the camshaft.




Additionally, these precision parts may be easily fouled or jammed by contamination inherent in hydraulic systems. Relatively large contamination particles often lodge between lands on the spool valve and lands on a valve housing to jam the valve and render the VCT inoperative. Likewise, relatively small contamination particles may lodge between the outer diameter of the check or spool valve and the inner diameter of the valve housing to similarly jam the valve. Such contamination problems are typically approached by targeting a “zero contamination” level in the engine or by strategically placing independent screen filters in the hydraulic circuitry of the engine. Such approaches are known to be relatively expensive and only moderately effective to reduce contamination.




Another problem with such VCT systems is the inability to properly control the position of the spool during the initial start-up phase of the engine. When the engine first starts, it takes several seconds for oil pressure to develop. During that time, the position of the spool valve is unknown. Because the system logic has no known quantity in terms of position with which to perform the necessary calculations, the control system is prevented from effectively controlling the spool valve position until the engine reaches normal operating speed. Finally, it has been discovered that this type of VCT system is not optimized for use with all engine styles and sizes. Larger, higher-torque engines such as V-8's produce torque pulses sufficient to actuate the hydraulic system of Such VCT systems. Regrettably however, smaller, lower-torque engines such as four and six cylinder's may not produce torque pulses sufficient to actuate the VCT hydraulic system.




Other VCT systems incorporate system hydraulics including a hub having multiple circumferentially spaced vanes cooperating within an enclosed housing having multiple circumferentially opposed walls. The vanes and the walls cooperate to define multiple fluid chambers, and the vanes divide the chambers into first and second sections. For example Shirai et al., U.S. Pat. No. 4,858,572, teaches use of such a system for adjusting an angular phase difference between an engine crankshaft and an engine camshaft. Shirai et al. further teaches that the circumferentially opposed walls of the housing limit the circumferential travel of each of the vanes within each chamber.




Shirai et al. discloses fluid circuits having check valves, a spool valve and springs, and electromechanical valves to transfer fluid within the housing from the first section to the second section, or vice versa, to thereby oscillate the vanes and hub with respect to the housing in one direction or the other. Shirai et al. Further discloses a first connecting means for locking the hub and housing together when each vane is in abutment with one of the circumferentially opposed walls of each chamber. A second connecting means is provided for locking the hub and housing together when each vane is in abutment with the other of the circumferentially opposed walls of each chamber. Such connecting means are effective to keep the camshaft position either fully advanced or fully retarded relative to the crankshaft.




Unfortunately, Shirai et al. has several shortcomings. First, the previously mentioned problems involved with using a spool valve and check valve configurations are applicable to Shirai et al. Second, this arrangement appears to be limited to a total of only 15 degrees of phase adjustment between crankshaft position and camshaft position. The more angle of cam rotation, the more opportunity for efficiency and performance gains. Thus, only 15 degrees of adjustment severely limits the efficiency and performance gains compared to other systems that typically achieve 30 degrees of cam rotation. Third, this arrangement is only a two-position configuration, being positionable only in either the fully advanced or fully retarded positions with no positioning in-between whatsoever. Likewise, this configuration limits the efficiency and performance gains compared to other systems that allow for continuously variable angular adjustment within the phase limits.




Therefore, what is needed is a VCT system that is designed to overcome the problems associated with prior art variable camshaft timing arrangements by providing a variable camshaft timing system that performs well with all engine styles and sizes, packages at least as tightly as prior art VCT hardware, eliminates the need for check valves and spool valves, provides for continuously variable camshaft to crankshaft phase adjustment within its operating limits, and provides substantially more than 15 degrees of phase adjustment between the crankshaft position and the camshaft position.




SUMMARY OF THE INVENTION




According to the present invention there is provided a Variable Camshaft Timing (VCT) system that is designed to overcome the problems associated with prior art variable camshaft timing arrangements. The present invention provides a variable camshaft timing system that performs well with all engine styles and sizes, packages at least as tightly as prior art VCT hardware, eliminates the need for check valves and spool valves, provides for continuously variable camshaft to crankshaft phase adjustment within its operating limits, and provides substantially more than 15 degrees of phase adjustment between the crankshaft position and the camshaft position.




In one form of the invention, there is provided a camshaft and a hub secured to the camshaft for rotation synchronous with the camshaft. 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. A plurality of driving vanes is radially disposed in the housing and cooperates with an external surface on the hub. Likewise, a plurality of driven vanes is radially disposed in the hub and cooperates with an internal surface of the housing. A locking arrangement reactive to oil pressure is provided for preventing relative motion between the housing and the hub at any of a multitude of circumferential positions of the housing and the hub relative to one another. Finally, a configuration for controlling the oscillation of the housing relative to the hub is provided.




Accordingly, it is an object of the present invention to provide an improved variable camshaft timing arrangement for an internal combustion engine.




It is another object to provide a variable camshaft timing arrangement in which the position of a camshaft is continuously variable relative to the position of the crankshaft within its operating limits.




It is still another object to provide a hydraulically operated variable camshaft timing arrangement of relatively simplified mechanical and hydraulic construction in contrast to an arrangement that requires check valves and spool valves.




It is yet another object to provide an improved VCT system that performs with all engine styles and sizes.




It is a further object to provide a VCT system that packages as tightly as previous VCT systems and eliminates the need for check valves and spool valves,




It is still a further object to provide a VCT that provides for continuously variable camshaft to crankshaft phase adjustment within its operating limits, and that provides at least approximately 30 degrees of phase adjustment between the crankshaft position and the camshaft position.




These objects and other features, aspects, and advantages of this invention i.


0


will be more apparent after a reading of the following detailed description, appended claims, and accompanying drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of a camshaft and vane phaser according to the present invention;





FIG. 2

is an end view ol the camshaft and vane phaser of

FIG. 1

;





FIG. 3

is an end view of another camshaft having a vane phaser according to the present invention;





FIG. 4

is a schematic view of the hydraulic equipment of the camshaft and vane phaser arrangement according to the preferred embodiment of the present invention and illustrates a phase shift where the position of the camshaft is changing from neutral position to a retard position;





FIG. 5

is a cross-sectional view of components of the variable camshaft timing system of the present invention in the position of such components as illustrated in

FIGS. 4 and 6

;





FIG. 6

is a schematic view of the hydraulic equipment of the variable cam timing arrangement according to the preferred embodiment of the present invention and illustrates a phase shift where the position of the camshaft is changing from neutral position to an advance position;





FIG. 7

is a schematic view of the hydraulic equipment of the variable camshaft timing arrangement according to the preferred embodiment of the present invention and illustrates a locked condition where the position of the camshaft is neutral and the housing is locked to the camshaft;





FIG. 8

is a cross-sectional view of components of the variable camshaft timing system of the present invention in the position of such components as illustrated in

FIG. 7

;





FIG. 9

is a schematic view of the hydraulic equipment of the variable camshaft timing arrangement according to an alternative embodiment of the present invention and illustrates a phase shift where the position of the camshaft is changing from neutral position to an advance position, and further illustrates use of a three-way solenoid to unlock the housing from the camshaft;





FIG. 9A

is an end view of another camshaft and vane phaser according to the present invention; and





FIG. 10

is a schematic view of the hydraulic equipment of the variable camshaft timing arrangement according to another alternative embodiment of the present invention and illustrates a phase shift where the position of the camshaft is changing from neutral position to an advance position, and further illustrates oil pressure flowing directly to a locking piston to unlock the housing from the camshaft.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT




In general, a hydraulic timing system is provided for varying the phase of one rotary member relative to another rotary member. More particularly, the present invention provides a multi-position Variable camshaft Timing (VCT) system powered by engine oil for varying the timing of a camshaft of an engine relative to a crankshaft of an engine to improve one or more of the operating characteristics of the engine. While the present invention will be described in detail with respect to internal combustion engines, the VCT system is also well suited to other environments using hydraulic timing devices. Accordingly, the present invention is not limited to only internal combustion engines.




Referring now in detail to the Figures, there is shown in

FIGS. 1 and 2

a vane phaser


10


according to the preferred embodiment of the present invention. The vane phaser


10


includes a housing


24


or sprocket circumscribing a hub


40


. The housing


24


includes sprocket teeth


26


disposed about its periphery and an annular array of locking teeth


30


disposed about a locking diameter


28


. The housing


24


further includes an internal


20


surface


32


and internal lobes


34


circumferentially spaced apart with a radial slot


34




a


in each lobe. Each radial slot


34




a


extends outwardly and is open to the internal surface


32


. The housing


24


includes a driving vane


36


radially and slidably disposed in each radial slot


34




a


. Each driving vane


36


has an inner edge


36




a


that engages an external surface


42


of the hub


40


. Each driving vane


36


is spring-loaded by a bias member or spring


38


radially inwardly to ensure constant contact with the external surface


42


of the hub


40


.




The hub


40


includes external lobes


44


circumferentially spaced apart, around an external surface


42


, and a radial slot


44




a


in each external lobe


44


. The hub


40


includes a driven vane


46


radially and slidably disposed in each radial slot


44


a. Each driven vane


46


has an outer edge


46




a


that engages the internal surface


32


of the housing


24


. Each driven vane


46


is biased radially outwardly by a bias member or spring


48


to ensure constant contact with the internal surface


32


of the housing


24


. In that regard, each outer edge


46


A of each driven vane


46


of the hub


40


slidably cooperates with the internal surface


32


of the housing


24


. Likewise, each inner edge


36


A of each driving vane


36


of the housing


24


slidably cooperates with the external surface


42


of the hub


40


to permit limited relative movement between the hub


40


and the housing


24


.




The driving and driven vanes


36


and


46


are alternately circumferentially interspersed to define advance chambers


12


and retard chambers


14


. Therefore, the advance and retard chambers


12


and


14


are also alternately circumferentially interspersed between the hub


40


and the housing


24


. In addition, the advance and retard chambers


12


and


14


are fluid tightly separated from one another.





FIG. 3

illustrates another vane phaser


110


according to an alternative


20


embodiment of the present invention. Here the vane phaser


110


design is more similar to ordinary vane pump design and includes a rotor or hub


140


and housing


124


. In contrast to the vane phaser


10


of

FIGS. 1 and 2

, this vane phaser


110


has no lobes. Rather, a driven vane


146


is disposed in each radial slot


144


in the hub


140


and a driving vane


136


is disposed in each radial slot


134


in the housing


124


.




Referring now to

FIGS. 4

,


6


, and


7


, the vane phaser


10


of the variable camshaft timing system according to the preferred embodiment of the present invention is provided in schematic form. The vane phaser


1




0


includes the housing


24


having the driving vanes


36


extending inwardly therefrom. The hub


40


includes the driven vanes


46


extending outwardly therefrom. The hub


40


is keyed or otherwise secured to a camshaft


50


to be rotatable therewith, but not oscillatable with respect thereto. The assembly that includes the camshaft


50


with the hub


40


and housing


24


is caused to rotate by torque applied to the housing


24


by an endless chain (not shown) that engages the sprocket teeth


26


, so that motion is impacted to the endless chain by a rotating crankshaft (not shown). The housing


24


, rotates with the camshaft


50


and is oscillatable with respect to the camshaft


50


to change the phase of the camshaft


50


relative to the crankshaft.




A locking arrangement is enabled using pressurized engine oil that flows into the camshaft


50


by way of a supply passage


54


in a camshaft bearing


52


(as indicated by the directional arrows). The engine oil flows first to a 3-way on/off flow control valve


16


whose operation is controlled by an electronic engine control unit (ECU)


18


. As shown in

FIGS. 4 and 6

, when the 3-way valve


16


is on, oil flows through the 3-way valve


16


into a locking passage


56


in the camshaft


50


against a locking plate


70


. The oil pressure thereby urges the locking plate


70


, against the force of a return spring


72


, to a position where the locking plate


70


maintains the vane phaser


10


in an unlocked condition by structure that will hereinafter be described in greater detail. In

FIG. 7

, however, the 3-way valve


16


is off and no engine oil, therefore, will flow into the locking passage


56


, whereupon the return spring


72


will return the locking plate


70


to its locked position.




Referring now to

FIGS. 5 and 8

, the locking plate


70


is in the form of an annular member that is coaxially positioned relative to the longitudinal central axis of the camshaft


50


. A locking ring


66


is provided with an annular array of locking teeth


68


that is positioned to engage the locking teeth


30


on the housing


24


when the locking plate


70


moves along the longitudinal central axis of the camshaft


50


from the unlocked position shown in

FIG. 5

to the locked position shown in FIG.


8


. As heretofore explained in connection with

FIGS. 4

,


6


, and


7


, the locking plate


70


is biased toward its locked position of

FIG. 8

by the return spring


72


, which bears against an axial surface


70


A of the locking plate


70


to which the locking ring


66


is secured by a snap ring


78


. The locking plate


70


is urged to its unlocked position of

FIG. 5

by hydraulic pressure through the locking passage


56


shown in

FIGS. 4

,


6


, and


7


. The hydraulic pressure bears against an axial surface


70


B of the locking plate


70


that is opposed to the axial surface


70


A acted upon by the return spring


72


.




As heretofore explained, the locking plate


70


is incapable of circumferential movement relative to the camshaft


50


, whereas the housing


24


is capable of circumferential movement relative to the camshaft


50


. For this reason, and because of the multitude of intercommunicating locking teeth


30


and


68


, the locking plate


70


and locking ring


66


are capable of locking the housing


24


in a fixed circumferential position relative to the camshaft


50


at a multitude of relative circumferential positions therebetweeni. This occurs whenever hydraulic pressure in the locking passage (not shown) falls below a predetermined value needed to overcome the force of the return spring


72


.




As shown in

FIGS. 5 and 8

, the housing


24


is open at either axial end but is closed off by separate spaced apart end plates


80




a


and


80




b


.The assembly that includes the locking plate


70


, the end plates


80




a


and


80




b


, the housing


24


, and the hub


40


is secured to an annular flange


58


of the camshaft


50


by bolts


82


each of which passes through each of the external lobes


44


of the hub


40


. In that regard, the locking plate


70


is slidable relative to a head


84


of each bolt


82


, as can be seen by comparing the relative unlocked and locked positions of

FIGS. 5 and 8

.




As shown in

FIGS. 4 and 6

, a control configuration is enabled using pressurized engine oil from the supply passage


54


that flows through the 3-way valve into a 4-way pulse width modulation control valve


20


for closed-loop control. The 4-way valve


20


is in fluid communication with an advancing fluid passage


60


and a retarding fluid passage


62


in the camshaft


50


that communicate through aligned apertures


76


in a sleeve portion


74


of the locking plate


70


to the advance and retard chambers


12


and


14


between the hub


40


and housing


24


. When the locking plate


70


is in the unlocked position, oil may flow to and from the advance and retard chambers


12


and


14


with respect to the 4-way valve


20


.




As shown in

FIG. 7

, however, when the locking plate


70


is in the locked position, the aligned apertures


76


of the slidable annular member do not align with the advancing fluid passage


60


and retarding fluid passage


62


, and therefore block flow of engine oil to and from the 4-way valve


20


with respect to the advance and retard chambers


12


and


14


.




In operation, as shown in

FIG. 4

, when the engine is started the pressurized oil begins to flow through the camshaft bearing


52


and into the 3-way valve


16


and through the 3-way valve


16


into the 4-way valve


20


. The engine control unit


18


processes input information from sources within the engine and elsewhere, then sends output information to various sources including the 3-way valve


16


. The 3-way valve


16


directs engine oil to the locking passage


56


based upon output from the engine control unit


18


to unlock the locking plate


70


, which then allows the vane phaser


10


to shift phase. The engine control unit may then signal the 4-way valve


20


to direct oil from a supply port


20


S to a retard port


20


R through to the retarding fluid passage


62


and into the retard chambers


14


. Simultaneously, engine oil is allowed to exhaust from the advance chambers


12


through the advancing fluid passage


60


into an advance port


20


A of the 4-way valve


20


and out an exhaust port


20


E. Attentively, as shown in

FIG. 6

, the engine control unit


18


may signal the 4-way valve


20


to direct oil from the supply port


20


S to the advance port


20


A through the advancing fluid passage


60


and into the advance chambers


12


. Simultaneously, engine oil is allowed to exhaust from the retard chambers


14


through the retarding fluid passage


62


into the retard port


20


R of the 4-way valve


20


and out the exhaust port


20


E.




As shown in

FIG. 7

, once the desired phase shift has been achieved, the engine control unit


18


will signal the 3-way valve


16


to permit the oil to exhaust from the locking plate


70


through the locking passage


56


through a locking port


16


L of the 3-way valve


16


and out an exhaust port


16


E. Simultaneously, all engine oil flow to and from the advance and retard chambers


12


and


14


with respect to the 4-way valve


20


will cease since the locking plate


70


slides to a locked position to block oil flow and lock the vane phaser


10


in position.





FIGS. 9 and 9A

illustrate a vane phaser


210


according to an alternative embodiment of the present invention.

FIG. 9

illustrates how the 3-way valve


16


, an advancing fluid passage


260


in a camshaft


250


, and bias members


290


in each of the retard chambers


14


perform the phase shift of the camshaft


250


under closed-loop control. Ilere, the bias members


290


act upon the driven vanes


46


to bias the hub


40


and driven vanes


46


in a fully retarded position under 0% duty cycle. Accordingly, in order to counterbalance the spring force of the bias members


290


, oil pressure under 100% duty cycle flows from the supply passage


254


through the 3-way valve


16


and advancing fluid passage


260


into each of the advance chambers


12


. Therefore, the phase shift is achieved simply by controlling flow of oil pressure into each advance chamber


12


.





FIG. 9A

illustrates that the vane phaser


210


incorporates compression springs for the bias members


290


. Other springs, however, may be employed such as torsional springs, accordion springs, and beehive compression spriings. It is contemplated that the bias on the hub


40


may also be achieved using a single spring member configuration (not shown). Additionally, the hub


40


may instead be normally biased toward the fully advanced position (not shown), whereby phase shift would be achieved by controlling flow into the retard chambers


14


.




Finally,

FIG. 10

also illustrates a vane phaser


310


according to an alternative embodiment of the present invention in which the locking plate


70


is always disengaged while oil flows through the camshaft bearing


52


mounted around a camshaft


350


. In this configuration, once oil pressure is high enough to overcome the force of the return spring


72


the locking plate


70


will disengage. Therefore, the locking plate


70


will be disengaged all the time that the engine is running and supplying oil pressure. Accordingly, the vane phaser


310


will be able to move to any position within the accuracy of the phaser control scheme.




From the above, it can be appreciated that a significant advantage of the present invention is that no check valves or spool valves are required, and thus the VCT will likely be less susceptible to contamination problems.




An additional advantage is that the VCT of the present invention maintains a similar dimensional size as current self-powered VCT phaser mechanisms, yet operates effectively from engine oil pressure and does not require actuation from torque pulses from the camshaft. In order to reduce the size of the vane phaser, the present invention includes a vane phase configuration of less cross-sectional area and having more vane chambers to achieve comparable volume with respect to prior art vane phases. Accordingly, the phaser can achieve 30 degrees of cam phase rotation yet maintain a cross-sectional width of less than 15 mm.




Another advantage is that the VCT of the present invention shares many characteristics with traditional vane-style pumps and therefore may share vane pump componentry and the benefit of long established vane pump design and manufacturing principles.




Yet another advantage is that no additional seal system is required to seal the alleviating advance and retard chambers since the driving and driven vanes are spring loaded into constant contact with the hub and housing respectively.




While the present invention has been described in terms of a preferred embodiment, it is apparent that other forms could be adopted by one skilled in the art. For example, an open-loop control strategy could be employed to achieve the phase shift of the camshaft. Likewise, alternative control valve devices may be employed to control fluid flow. Additionally, the reader's attention is directed to all papers and documents filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. Accordingly, the scope of the present invention is to be limited only by the following claims.



Claims
  • 1. An internal combustion engine comprisinga camshaft; a hub secured to said camshaft for rotation therewith, said hub having an external surface thereon; a housing circumscribing said hub, said housing having an internal surface thereon, said housing being rotatable with said hub and said camshaft and being oscillatable with respect to said hub and said camshaft; a plurality of driving vanes radially disposed in said housing and cooperating with said external surface of said hub; a plurality of driven vanes radially disposed in said hub and alternating with said plurality of driving vanes and cooperating with said internal surface of said housing; said plurality of driving and driven vanes defining a plurality of alternating advance and retard chambers; locking means for preventing relative motion between said housing and said hub in at least one position between a fully advanced position of said hub relative to said housing and a fully retarded position of said hub relative to said housing, said locking means being reactive to engine oil pressure; and means for controlling oscillation of said housing relative to said hub.
  • 2. The internal combustion engine as claimed in claim 1, wherein said housing includes a first set of locking teeth and further wherein said locking means comprises:a locking plate circumscribing a portion of said camshaft; a locking ring connected to said locking plate, said locking ring including a second set of locking teeth being in engagement with said first set of locking teeth of said housing in a locked position to prevent relative circumferential motion between said hub and said housing, and being out of engagement with said first set of locking teeth in an unlocked position to permit relative circumferential motion between said hub and said housing; and resilient means for biasing said locking plate and said locking ring toward said locked position.
  • 3. The internal combustion engine as claimed in claim 2, wherein said locking ring is coaxially positioned relative to the longitudinal axis of said camshaft and is moveable along the longitudinal axis of said camshaft between said locked position and said unlocked position.
  • 4. The internal combustion engine as claimed in claim 3, wherein said locking plate has a radially extending flange and wherein said resilient means engages an axial surface of said radially extending flange.
  • 5. The internal combustion engine as claimed in claim 4, wherein said locking means further comprises:a passage extending through said camshaft for delivering engine oil pressure to said locking plate, where engine oil pressure acts against an opposed axial surface of said radially extending flange of said locking plate to counteract a force imposed on said locking plate by said resilient means.
  • 6. The internal combustion engine as claimed in claim 5 further comprising:a control valve for controlling flow of engine oil pressure into said passage extending through said camshaft.
  • 7. The internal combustion engine as claimed in claim 6 fulrther comprising:an electronic engine control unit for controlling operation of said control valve to control whether said control valve operates in an on mode or in an off mode.
  • 8. The internal combustion engine as claimed in claim 1, wherein said controlling means comprises:an electronic engine control unit; valuing means for directing engine oil pressure and being responsive to said electronic engine control unit; advancing means for communicating engine oil pressure between said valuing means and said plurality of advance chambers; and retarding means for communicating engine oil pressure between said valuing means and said plurality of said retard chambers.
  • 9. The internal combustion engine as claimed in claim 8, wherein said advancing means includes neither a check valve nor a spool valve.
  • 10. The internal combustion engine as claimed in claim 8, wherein said valuing means includes a control valve comprising:an advance control port communicating with said advancing means, a retard control port communicating with said retarding means, a supply port for supplying engine oil pressure, and an exhaust port for exhausting engine oil pressure.
  • 11. The internal combustion engine as claimed in claim 8, wherein each of said plurality of driving vanes is biased against each of said plurality of said driven vanes to maximize the volume of either said plurality of advance chambers or said plurality of retard chambers, and said controlling means including either said advancing means or said retarding means respectively supplying one of said plurality of advance chambers and said plurality of retard chambers with engine oil pressure to counterbalance said plurality of driving vanes biased against said plurality of driven vanes.
  • 12. An internal combustion engine comprising:a camshaft; a hub secured to said camshaft for rotation therewith, said hub having an external surface thereon; a housing circumscribing said hub to define a fluid chamber therebetween, said housing having an internal surface thereon, said housing being rotatable with said hub and said camshaft and being oscillatable with respect to said hub and said camshaft; a plurality of driving vanes radially disposed in said housing and extending in an inwardly radial direction therefrom into said fluid chamber and cooperating with said external surface of said hub; a plurality of driven vanes radially disposed in said hub and extending radially outwardly therefrom into said fluid chamber and cooperating with said internal surface of said housing; said plurality of driving and driven vanes dividing said fluid chamber into a plurality of advance chambers and a plurality of retard chambers circumferentially interspersed with said plurality of advance chambers; locking means for preventing relative motion between said housing and said hub in at least one position between a fully advanced position of said hub relative to said housing and a fully retarded position of said hub relative to said housing, said locking means being reactive to engine oil pressure; and means for controlling oscillation of said hub relative to said housing, said controlling means comprises means for porting said plurality of advance and retard chambers with engine oil pressure to relatively displace said plurality driving and driven vanes.
  • 13. The internal combustion engine as claimed in claim 12, wherein said housing includes a first set of locking teeth and further- wherein said locking means comprises:a locking plate circumscribing a portion of said camshaft; a locking ring connected to said locking plate, said locking ring including a second set of locking teeth being in engagement with said first set of locking teeth of said housing in a locked position to prevent relative circumferential motion between said hub and said housing, and being out of engagement with said first set of locking teeth in an unlocked position to permit relative circumferential motion between said hub and said housing, said locking plate being coaxially positioned relative to the longitudinal axis of said camshaft and moveable along the longitudinal axis of said camshaft between said locked and said unlocked position; and resilient means for biasing said locking plate and said locking ring toward said locked position.
  • 14. The internal combustion engine as claimed in claim 13, said locking means further comprising:a radially extending flange thereon and wherein said resilient means engages an axial surface of said radially extending flange; and a passage extending through said camshaft for delivering engine oil pressure to said locking plate, where engine oil pressure acts against an opposed axial surface of said radially extending flange of said locking plate for counterbalancing a force imposed on said locking plate by said resilient means.
  • 15. The internal combustion engine as claimed in claim 14 further comprising:an on/off control valve for controlling flow of engine oil pressure into said passage extending through said camshaft; and an electronic engine control unit for controlling operation of said on/off control valve to control whether said on/off control valve operates in an on mode or in an off mode.
  • 16. The internal combustion engine as claimed in claim 12, wherein said controlling means further comprises:an electronic engine control unit; valving means for directing engine oil pressure and being responsive to said electronic engine control unit; advancing means for communicating engine oil pressure between said valving means and said plurality of advance chambers, wherein said advancing means comprises an advancing fluid passage through said camshaft, said hub, and said locking means, said advancing fluid passage communicating with said advance chambers, whereby engine oil pressure flows finely through said advancing fluid passage when said locking means is in said unlocked position and engine oil pressure is blocked when said locking means is in said locked position; and retarding means for communicating engine oil pressure between said valving means and said plurality of said retard chambers, wherein said retarding means comprises a retarding fluid passage through said camshaft, said hub, and said locking means, said retarding fluid passage communicating with said retard chambers, whereby engine oil pressure flows freely through said retarding fluid passage when said locking means is in said unlocked position and engine oil pressure is blocked when said locking means is in said locked position.
  • 17. The internal combustion engine as claimed in claim 16, wherein said advancing means includes neither a check valve nor a spool valve.
  • 18. The internal combustion engine as claimed in claim 16, wherein said valving means includes a four-way pulse-width-modulated valve comprising:an advance control port communicating with said advancing means, a retard control port communicating with said retarding means, a supply port for supplying engine oil pressure, and an exhaust port for exhausting engine oil pressure.
  • 19. The internal combustion engine as claimed in claim 16, wherein each of said plurality of driving vanes is biased against each of said plurality of said driven vanes to maximize the volume of either said plurality of advance chambers or said plurality of retard chambers, and said controlling means including either said advancing means or said retarding means respectively supplying one of said plurality of advance chambers and said plurality of retard chambers with engine oil pressure to counterbalance said plurality of driving vanes biased against said plurality of driven vanes.
  • 20. An internal combustion engine comprising:a crankshaft; a camshaft linked to and rotatably driven by said crankshaft; a hub secured to said camshaft for rotation therewith, said hub having an external surface thereon, said hub further having inwardly extending radial slots open to said external surface and being circumferentially spaced apart, said hub being non-oscillatable with respect to said camshaft; a housing circumscribing said hub, said housing having an internal surface thereon, said housing being rotatable with said hub and said camshaft and being oscillatable with respect to said hub and said camshaft, said housing further having outwardly extending radial slots open to said internal surface and being circumferentially spaced apait, said internal surface being circumferentially larger than said external surface of said hub thereby defining a fluid chamber therebetween; a plurality of driving vanes radially and slidably disposed in said outwardly extending radial slots of said housing and corresponding in quantity to said outwardly extending radial slots of said housing, each of said plurality of driving vanes having an inner edge engaging said external surface of said hub, said plurality of driving vanes being spring-loaded radially inwardly to ensure constant contact with said external surface of said hub; a plurality of driven vanes radially and slidably disposed in said inwardly extending radial slots of said hub and corresponding in quantity to said inwardly extending radial slots of said hub, each of said plurality of driven vanes having an outer edge engaging said internal surface of said housing, said plurality of driven vanes being spring-loaded radially outwardly to ensure constant contact with said internal surface of said housing; said plurality of driving and driven vanes defining a plurality of advance chambers and a plurality of retard chambers circumferentially alternatively interspersed among said plurality of advance chambers within said fluid chamber, said plurality of alternating advance and retard chambers being fluid tightly separated from each other; locking means for preventing relative motion between said housing and said hub in at least one position between a fully advanced position of said hub relative to said housing and a fully retarded position of said hub relative to said housing, said locking means being reactive to engine oil pressure; and means for controlling oscillation of said hub relative to said housing, said controlling means comprises means for porting said plurality of advance chambers, and means for porting said plurality of retard chambers, said controlling means being capable of supplying said plurality of alternating advance and retard chambers with engine oil pressure and being capable of exhausting said plurality of alternating advance and retard chambers of engine oil pressure to relatively displace said plurality of driving and driven vanes.
  • 21. The internal combustion engine as claimed in claim 20, wherein said housing includes a first set of locking teeth and further wherein said locking means comprises:a locking plate circumscribing a portion of said camshaft; a locking ring connected to said locking plate, said locking ring including a second set of locking teeth being in engagement with said first set of locking teeth of said housing in a locked position to prevent relative circumferential motion between said hub and said housing, and being out of engagement with said first set of locking teeth in an unlocked position to permit relative circumferential motion between said hub and said housing; and resilient means for biasing said locking ring and locking plate toward said locked position.
  • 22. The internal combustion engine as claimed in claim 21, wherein said controlling means further comprises:an electronic engine control unit; valving means for directing engine oil pressure and being responsive to said electronic engine control unit; advancing means for communicating engine oil pressure between said valving means and said plurality of advance chambers; and retarding means for communicating engine oil pressure between said valving means and said plurality of said retard chambers.
  • 23. The internal combustion engine as claimed in claim 20, wherein said advancing means includes neither a check valve nor a spool valve.
CROSS-REFERENCES

The present application is related to pending application Ser. No. 09/450,456 filed Nov. 29, 1999, and entitled “Variable Valve Timing with Actuator Locking for Internal Combustion Engine”, by inventor Roger T. Simpson Additionally, the present application is related to copending application Ser. No. 09/488,903 filed on the same date herewith, and entitled “Multi-Position Variable Cam Timing System Having a Vane-Mounted Locking-Piston Device”, by inventors Roger T. Simpson, and Michael Duffield, and thus is incorporated by reference herein. Finally, the present application is related to copending application Ser. No. 9/592,624 also filed on the same date herewith, and entitled “Control Valve Strategy for Vane-Typc Variable Camshaft Timing System”, by inventors Roger T. Simpson and Michael Duffield and thus is also incorporated by reference herein.

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