Camshaft phaser

A camshaft phaser includes an input member and an output member. A valve spool is moveable along an axis between an advance position and a retard position and includes a valve spool bore. A check valve within the valve spool bore includes a check valve member which moves between a seated position and an unseated position such that the check valve member prevents fluid flow out of the valve spool bore through a passage and such that the check valve member permits flow into the valve spool bore through the passage. An insert within the valve spool bore supports the check valve closes one end of the valve spool bore and abuts an insert retainer to retain the insert within the valve spool bore. A spring urges the insert toward the insert retainer and holds the insert retainer in compression against the insert retainer.

TECHNICAL FIELD OF INVENTION

The present invention relates to a camshaft phaser for varying the phase relationship between a crankshaft and a camshaft in an internal combustion engine; more particularly to such a camshaft phaser which includes a valve for changing position of the camshaft phaser.

BACKGROUND OF INVENTION

A typical vane-type camshaft phaser for changing the phase relationship between a crankshaft and a camshaft of an internal combustion engine generally comprises a plurality of outwardly-extending vanes on a rotor interspersed with a plurality of inwardly-extending lobes on a stator, forming alternating advance and retard chambers between the vanes and lobes. Engine oil is selectively supplied to one of the advance and retard chambers and vacated from the other of the advance and retard chambers by a phasing oil control valve in order to rotate the rotor within the stator and thereby change the phase relationship between the camshaft and the crankshaft. A supply check valve is typically provided in order to prevent oil from flowing back to the source of the engine oil. It is also common to include a lock pin which is selectively engaged and disengaged with a lock pin seat. When the lock pin is engaged with the lock pin seat, rotation of the rotor relative to the stator is prevented. Conversely, when the lock pin is disengaged from the lock pin, rotation of the rotor relative to the stator is permitted based on input from the phasing oil control valve. One such camshaft phaser is described in U.S. Pat. No. 6,772,721 to Gardner et al., hereinafter referred to as Gardner et al. While the camshaft phaser of Gardner et al. may be effective, it may be difficult to implement the check valve within the rotor as taught by Gardner et al. In order to achieve compactness and simplify oil passages, it may be desirable to implement the check valve within the valve spool.

U.S. Pat. No. 10,082,054 to Haltiner Jr., et al., the entire disclosure of which is incorporated herein by reference in its entirety, discloses another such camshaft phaser. In Haltiner Jr. et al., the check valve is implemented within the valve spool together with an insert which separates the interior of the valve spool into a phasing chamber and a vent chamber which are fluidly segregated. While Haltiner Jr. et al. may be effective, it may be challenging to provide a seal between the interface of the insert and the valve spool and the check valve may be subject to relative movement between the check valve and the insert which may promote wear over the expected service life of the camshaft phaser.

What is needed is camshaft phaser which minimizes or eliminates one or more the shortcomings as set forth above.

SUMMARY OF THE INVENTION

Briefly described, a camshaft phaser is provided for use with an internal combustion engine for controllably varying the phase relationship between a crankshaft and a camshaft in the internal combustion engine. The camshaft phaser includes an input member connectable to the crankshaft of the internal combustion engine to provide a fixed ratio of rotation, about an axis of rotation, between the input member and the crankshaft; an output member connectable to the camshaft of the internal combustion engine and defining an advance chamber and a retard chamber with the input member; a valve spool moveable along the axis of rotation between an advance position and a retard position and having a valve spool bore extending thereinto along the axis of rotation, wherein the advance position allows oil to be vented from the advance chamber and to be supplied to the retard chamber from the valve spool bore in order to advance the timing of the camshaft relative to the crankshaft and wherein the retard position allows oil to be vented from the retard chamber and to be supplied to the advance chamber from the valve spool bore in order to retard the timing of the camshaft relative to the crankshaft; a check valve within the valve spool bore, the check valve including a check valve member which moves between a seated position and an unseated position such that the check valve member prevents fluid flow out of the valve spool bore through a passage and such that the check valve member permits flow into the valve spool bore through the passage; an insert within the valve spool bore such that the insert supports the check valve within the valve spool bore and sealingly closes one end of the valve spool bore; an insert retainer with which the insert is abutted and retains the insert within the valve spool bore; and a spring which urges the insert toward the insert retainer and holds the insert retainer in compression against the insert retainer. The camshaft phaser including the valve spool, the insert, and the check valve as described herein allows for simplified construction of the camshaft phaser compared to the prior art and ensures that the check valve and insert remain static within the valve spool during operation.

Further features and advantages of the invention will appear more clearly on a reading of the following detail description of the preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.

DETAILED DESCRIPTION OF INVENTION

Referring toFIGS. 1-4, an internal combustion engine10is shown which includes a camshaft phaser12. Internal combustion engine10also includes a camshaft14which is rotatable about an axis of rotation16based on rotational input from a crankshaft and belt (not shown) driven by a plurality of reciprocating pistons (also not shown). As camshaft14is rotated, it imparts valve lifting and closing motion to intake and/or exhaust valves (not shown) as is well known in the internal combustion engine art. Camshaft phaser12allows the timing between the crankshaft and camshaft14to be varied. In this way, opening and closing of the intake and/or exhaust valves can be advanced or retarded in order to achieve desired engine performance.

Camshaft phaser12generally includes a stator18which acts and an input member, a rotor20disposed coaxially within stator18which acts as an output member, a back cover22closing off one end of stator18, a front cover24closing off the other end of stator18, a lock pin26, a camshaft phaser attachment bolt28for attaching camshaft phaser12to camshaft14, and a valve spool30. The various elements of camshaft phaser12will be described in greater detail in the paragraphs that follow.

Stator18is generally cylindrical and includes a plurality of radial chambers31defined by a plurality of lobes32extending radially inward. In the embodiment shown, there are four lobes32defining four radial chambers31, however, it is to be understood that a different number of lobes32may be provided to define radial chambers31equal in quantity to the number of lobes32. Stator18may also include a toothed pulley34formed integrally therewith or otherwise fixed thereto. Pulley34is configured to be driven by a belt that is driven by the crankshaft of internal combustion engine10. Alternatively, pulley34may be a sprocket driven by a chain or any other known drive member known for driving camshaft phaser12by the crankshaft.

Rotor20includes a central hub36with a plurality of vanes38extending radially outward therefrom and a rotor central through bore40extending axially therethrough. The number of vanes38is equal to the number of radial chambers31provided in stator18. Rotor20is coaxially disposed within stator18such that each vane38divides each radial chamber31into advance chambers42and retard chambers44. The radial tips of lobes32are mateable with central hub36in order to separate radial chambers31from each other. Each of the radial tips of vanes38may include one of a plurality of wiper seals46to substantially seal adjacent advance chambers42and retard chambers44from each other. While not shown, each of the radial tips of lobes32may also include one of a plurality of wiper seals46.

Back cover22is sealingly secured, using cover bolts48, to the axial end of stator18that is proximal to camshaft14. Tightening of cover bolts48prevents relative rotation between back cover22and stator18. A back cover seal50, for example only, an O-ring, may be provided between back cover22and stator18in order to provide an oil-tight seal between the interface of back cover22and stator18. Back cover22includes a back cover central bore52extending coaxially therethrough. The end of camshaft14is received coaxially within back cover central bore52such that camshaft14is allowed to rotate relative to back cover22. In an alternative arrangement, pulley34may be integrally formed or otherwise attached to back cover22rather than stator18.

Similarly, front cover24is sealingly secured, using cover bolts48, to the axial end of stator18that is opposite back cover22. A front cover seal54, for example only, an O-ring, may be provided between front cover24and stator18in order to provide an oil-tight seal between the interface of front cover24and stator18. Cover bolts48pass through back cover22and stator18and threadably engage front cover24, thereby clamping stator18between back cover22and front cover24to prevent relative rotation between stator18, back cover22, and front cover24. In this way, advance chambers42and retard chambers44are defined axially between back cover22and front cover24.

Camshaft phaser12is attached to camshaft14with camshaft phaser attachment bolt28which extends coaxially through rotor central through bore40of rotor20and threadably engages camshaft14, thereby by clamping rotor20securely to camshaft14. In this way, relative rotation between stator18and rotor20results in a change is phase or timing between the crankshaft of internal combustion engine10and camshaft14.

Pressurized oil is selectively supplied to advance chambers42from an oil source55, which may be an oil pump of internal combustion engine10, while oil is simultaneously vented from retard chambers44in order to cause relative rotation between stator18and rotor20which results in retarding the timing of camshaft14relative to the crankshaft of internal combustion engine10. Conversely, pressurized oil is selectively supplied to retard chambers44from oil source55while oil is simultaneously vented from advance chambers42in order to cause relative rotation between stator18and rotor20which results in advancing the timing of camshaft14relative to the crankshaft of internal combustion engine10. Rotor advance passages56may be provided in rotor20for supplying and venting oil to and from advance chambers42while rotor retard passages58may be provided in rotor20for supplying and venting oil to and from retard chambers44. Supplying and venting oil to and from advance chambers42and to and from retard chambers44is controlled by valve spool30, as will be described in detail later, such that valve spool30is coaxially disposed slidably within a valve bore64of camshaft phaser attachment bolt28where valve bore64is centered about axis of rotation16.

Lock pin26selectively prevents relative rotation between stator18and rotor20at a predetermined aligned position of rotor20within stator18, which as shown, may be a full advance position, i.e. rotor20as far as possible within stator18in the advance direction of rotation. Lock pin26is slidably disposed within a lock pin bore66formed in one vane38of rotor20. A lock pin seat68is provided in front cover24for selectively receiving lock pin26therewithin. Lock pin26and lock pin seat68are sized to substantially prevent rotation between stator18and rotor20when lock pin26is received within lock pin seat68. When lock pin26is not desired to be seated within lock pin seat68, pressurized oil is supplied to lock pin bore66through a rotor lock pin passage72formed in rotor20, thereby urging lock pin26out of lock pin seat68and compressing a lock pin spring70. Conversely, when lock pin26is desired to be seated within lock pin seat68, the pressurized oil is vented from lock pin bore66through rotor lock pin passage72, thereby allowing lock pin spring70to urge lock pin26toward front cover24. In this way, lock pin26is seated within lock pin seat68by lock pin spring70when rotor20is positioned within stator18to allow alignment of lock pin26with lock pin seat68. Supplying and venting of pressurized oil to and from lock pin26is controlled by valve spool30as will be described later.

Camshaft phaser attachment bolt28and valve spool30, which act together to function as a valve, will now be described in greater detail with continued reference toFIGS. 1-4and now with additional reference toFIGS. 5A-14. Camshaft phaser attachment bolt28includes bolt supply passages74which extend radially outward from valve bore64to the outside surface of camshaft phaser attachment bolt28. Bolt supply passages74receive pressurized oil from oil source55via an annular oil supply passage78formed radially between camshaft phaser attachment bolt28and a counter bore of camshaft14and also via radial camshaft oil passages80of camshaft14. The pressurized oil from oil source55is used to 1) selectively supply oil to advance chambers42, 2) selectively supply oil to retard chambers44, and 3) selectively disengage lock pin26from lock pin seat68. A filter82may circumferentially surround camshaft phaser attachment bolt28at bolt supply passages74in order to prevent foreign matter that may be present in the oil from reaching valve spool30.

Camshaft phaser attachment bolt28also includes a bolt annular lock pin groove84on the outer periphery of camshaft phaser attachment bolt28and bolt lock pin passages86extend radially outward from valve bore64to bolt annular lock pin groove84. Bolt annular lock pin groove84is spaced axially apart from bolt supply passages74in a direction away from camshaft14and is aligned with a rotor annular lock pin groove88which extends radially outward from rotor central through bore40such that rotor lock pin passage72extends from rotor annular lock pin groove88to lock pin bore66. In this way, fluid communication is provided between valve bore64and lock pin bore66.

Camshaft phaser attachment bolt28also includes a bolt annular advance groove90on the outer periphery of camshaft phaser attachment bolt28and bolt advance passages92extend radially outward from valve bore64to bolt annular advance groove90. Bolt annular advance groove90is spaced axially apart from bolt supply passages74and bolt annular lock pin groove84such that bolt annular lock pin groove84is axially between bolt supply passages74and bolt annular advance groove90. Bolt annular advance groove90is aligned with a rotor annular advance groove94which extends radially outward from rotor central through bore40such that rotor advance passages56extend from rotor annular advance groove94to advance chambers42. In this way, fluid communication is provided between valve bore64and advance chambers42.

Camshaft phaser attachment bolt28also includes a bolt annular retard groove96on the outer periphery of camshaft phaser attachment bolt28and bolt retard passages98extend radially outward from valve bore64to bolt annular retard groove96. Bolt annular retard groove96is spaced axially apart from bolt annular advance groove90such that bolt annular advance groove90is axially between bolt annular lock pin groove84and bolt annular retard groove96. Bolt annular retard groove96and is aligned with a rotor annular retard groove100which extends radially outward from rotor central through bore40such that rotor retard passages58extend from rotor annular retard groove100to retard chambers44. In this way, fluid communication is provided between valve bore64and retard chambers44.

Valve spool30is moved axially along axis of rotation16within valve bore64of camshaft phaser attachment bolt28by an actuator102and a valve spring104to achieve desired operational states of camshaft phaser12by opening and closing bolt supply passages74, bolt lock pin passages86, bolt advance passages92, and bolt retard passages98as will now be described. Valve spool30includes a valve spool bore106extending axially thereinto from the end of valve spool30that is proximal to camshaft14. An insert108is disposed within valve spool bore106such that insert108defines a phasing volume110and a venting volume112(best visible inFIG. 11) such that phasing volume110is substantially fluidly segregated from venting volume112, i.e. phasing volume110does not communicate with venting volume112. By way of non-limiting example only, insert108may be net-formed by plastic injection molding and may be easily inserted within valve spool bore106from the end of valve spool bore106that is proximal to valve spring104prior to valve spool30being inserted into valve bore64of camshaft phaser attachment bolt28. In this way, phasing volume110and venting volume112are easily and economically formed.

Valve spool30also includes a supply land114which is sized to fit within valve bore64in a close sliding relationship such that oil is substantially prevented from passing between the interface between supply land114and valve bore64while allowing valve spool30to be displaced axially within valve bore64substantially uninhibited.

Valve spool30also includes a spool annular supply groove116that is axially adjacent to supply land114. A spool supply passage118aand a spool supply passage118bare provided such that spool supply passage118aand spool supply passage118beach extend radially inward from spool annular supply groove116to phasing volume110within valve spool bore106and such that spool supply passage118ais diametrically opposed to spool supply passage118b. Spool supply passage118aand spool supply passage118bare both preferably slots which extend in a circumferential direction about axis of rotation16further than in the direction of axis of rotation16. A supply check valve120is disposed within phasing volume110, as will be described in greater detail later, in order to allow oil to enter phasing volume110from spool supply passage118aand from spool supply passage118bwhile substantially preventing oil from exiting phasing volume110to spool supply passage118aand to spool supply passage118b.

Valve spool30also includes a lock pin land122that is axially adjacent to spool annular supply groove116. Lock pin land122is sized to fit within valve bore64in a close sliding relationship such that oil is substantially prevented from passing between the interface between lock pin land122and valve bore64while allowing valve spool30to be displaced axially within valve bore64substantially uninhibited. Lock pin land122is axially divided by an spool annular lock pin groove124such that a spool lock pin passage126(best visible inFIG. 14) extends radially inward from spool annular lock pin groove124to venting volume112within valve spool bore106, thereby providing fluid communication between spool annular lock pin groove124and venting volume112.

Valve spool30also includes a spool annular advance groove128that is axially adjacent to lock pin land122. A spool advance passage130is provided which extends radially inward from spool annular advance groove128to phasing volume110within valve spool bore106in order to provide fluid communication between spool annular advance groove128and phasing volume110. Spool advance passage130is preferably a slot which extends in a circumferential direction about axis of rotation16further than in the direction of axis of rotation16and preferably extends circumferentially about half of the way around spool annular advance groove128.

Valve spool30also includes an advance land131that is axially adjacent to spool annular advance groove128. Advance land131is sized to fit within valve bore64in a close sliding relationship such that oil is substantially prevented from passing between the interface between advance land131and valve bore64while allowing valve spool30to be displaced axially within valve bore64substantially uninhibited.

Valve spool30also includes a spool annular vent groove132that is axially adjacent to advance land131. A spool vent passage134(best visible inFIGS. 12 and 14) is provided such that spool vent passage134extends radially inward from spool annular vent groove132to phasing volume110within valve spool bore106. Spool vent passage134is preferably a slot which extends in a circumferential direction about axis of rotation16further than in the direction of axis of rotation16and preferably extends circumferentially about half of the way around spool annular vent groove132.

Valve spool30also includes a retard land138that is axially adjacent to spool annular vent groove132. Retard land138is sized to fit within valve bore64in a close sliding relationship such that oil is substantially prevented from passing between the interface between retard land138and valve bore64while allowing valve spool30to be displaced axially within valve bore64substantially uninhibited.

Valve spool30also includes a spool annular retard groove140that is axially adjacent to retard land138. A spool retard passage142is provided such that spool retard passage142extends radially inward from spool annular retard groove140to phasing volume110within valve spool bore106in order to provide fluid communication between spool annular retard groove140and phasing volume110. Spool retard passage142is preferably a slot which extends in a circumferential direction about axis of rotation16further than in the direction of axis of rotation16and preferably extends circumferentially about half of the way around spool annular retard groove140.

Valve spool30also includes an end land144that is axially adjacent to spool annular retard groove140. End land144is sized to fit within valve bore64in a close sliding relationship such that oil is substantially prevented from passing between the interface between end land144and valve bore64while allowing valve spool30to be displaced axially within valve bore64substantially uninhibited.

Valve spool30also includes vent passages146which extend radially outward from venting volume112, thereby allowing oil within venting volume112to be vented to valve bore64and out of camshaft phaser12where it may be drained back to oil source55. Alternatively, a passage could be formed in camshaft phaser attachment bolt28which extends from valve bore64to a drain passage in camshaft14in order to vent oil within venting volume112where it may be drained back to oil source55.

Actuator102may be a solenoid actuator that is selectively energized with an electric current of varying magnitude in order to position valve spool30within valve bore64at desired axial positions, thereby controlling oil flow to achieve desired operation of camshaft phaser12. In a default position, when no electric current is supplied to actuator102as shown inFIGS. 5A and 5B, valve spring104urges valve spool30in a direction toward actuator102until valve spool30axially abuts a first stop member148, which may be, by way of non-limiting example only, a snap ring within a snap ring groove extending radially outward from valve bore64. In the default position, supply land114is positioned to provide fluid communication between bolt supply passages74and spool annular supply groove116, thereby allowing pressurized oil to be supplied to phasing volume110through spool supply passages118a,118band supply check valve120from oil source55. Also in the default position, lock pin land122is positioned to align spool annular lock pin groove124with bolt lock pin passages86, thereby allowing oil to be vented from lock pin bore66via rotor lock pin passage72, rotor annular lock pin groove88, bolt annular lock pin groove84, bolt lock pin passages86, spool annular lock pin groove124, spool lock pin passage126, venting volume112, and vent passages146and consequently allowing lock pin spring70to urge lock pin26toward front cover24. In the default position, lock pin land122also blocks fluid communication between bolt lock pin passages86and phasing volume110. Also in the default position, advance land131is positioned to block fluid communication between bolt advance passages92and spool annular vent groove132while simultaneously permitting fluid communication between bolt advance passages92and phasing volume110via spool annular advance groove128and spool advance passage130. Also in the default position, retard land138is positioned to block fluid communication between phasing volume110and bolt retard passages98while simultaneously permitting fluid communication between bolt retard passages98and venting volume112via spool annular vent groove132, and spool vent passage134. In this way, pressurized oil that is supplied to phasing volume110from oil source55is supplied to advance chambers42via spool advance passage130, spool annular advance groove128, bolt advance passages92, bolt annular advance groove90, rotor annular advance groove94, and rotor advance passages56while oil is simultaneously vented from retard chambers44via rotor retard passages58, rotor annular retard groove100, bolt annular retard groove96, bolt retard passages98, spool annular vent groove132, spool vent passage134, venting volume112, and vent passages146, thereby causing rotor20to rotate relative to stator18to cause a retard in timing of camshaft14relative to the crankshaft, and when lock pin26is aligned with lock pin seat68, lock pin spring70urges lock pin26into lock pin seat68to retain rotor20in the predetermined aligned position with stator18. InFIG. 5B, the reference numbers have been removed for clarity and arrows representing the path of travel of the oil have been included where arrows S represent oil from oil source55that is supplied to advance chambers42and arrows V represent vented oil from lock pin bore66and from retard chambers44. It should be noted thatFIG. 5Bshows supply check valve120being open, but supply check valve120may also be closed if a torque reversal acting on camshaft14causes the pressure within phasing volume110to be greater than the pressure of oil from oil source55.

In a retard position, when an electric current of a first magnitude is supplied to actuator102as shown inFIGS. 6A and 6B, actuator102urges valve spool30in a direction toward valve spring104thereby causing valve spring104to be compressed slightly. In the retard position, supply land114is positioned to provide fluid communication between bolt supply passages74and spool annular supply groove116, thereby allowing pressurized oil to be supplied to phasing volume110through spool supply passages118a,118band supply check valve120from oil source55. Also in the retard position, lock pin land122is positioned to prevent fluid communication between bolt lock pin passages86and spool annular lock pin groove124, thereby preventing oil from being vented from lock pin bore66. Also in the retard position, lock pin land122is positioned to permit fluid communication between bolt lock pin passages86and phasing volume110, thereby allowing pressurized oil to be supplied to lock pin bore66via spool advance passage130, spool annular advance groove128, bolt lock pin passages86, bolt annular lock pin groove84, rotor annular lock pin groove88, and rotor lock pin passage72, and as a result, lock pin26compresses lock pin spring70and lock pin26is retracted from lock pin seat68. Also in the retard position, advance land131is positioned to block fluid communication between bolt advance passages92and spool annular vent groove132while simultaneously permitting fluid communication between bolt advance passages92and phasing volume110via spool annular advance groove128and spool advance passage130. Also in the retard position, retard land138is positioned to block fluid communication between phasing volume110and bolt retard passages98while simultaneously permitting fluid communication between bolt retard passages98and venting volume112via spool annular vent groove132, and spool vent passage134. In this way, pressurized oil that is supplied to phasing volume110from oil source55is supplied to advance chambers42via spool advance passage130, spool annular advance groove128, bolt advance passages92, bolt annular advance groove90, rotor annular advance groove94, and rotor advance passages56while oil is simultaneously vented from retard chambers44via rotor retard passages58, rotor annular retard groove100, bolt annular retard groove96, bolt retard passages98, spool annular vent groove132, spool vent passage134, venting volume112, and vent passages146, thereby causing rotor20to rotate relative to stator18to cause a retard in timing of camshaft14relative to the crankshaft. InFIG. 6B, the reference numbers have been removed for clarity and arrows representing the path of travel of the oil have been included where arrows S represent oil from oil source55that is supplied to advance chambers42and to lock pin bore66and arrows V represent vented oil from retard chambers44. It should be noted thatFIG. 6Bshows supply check valve120being open, but supply check valve120may also be closed if a torque reversal acting on camshaft14causes the pressure within phasing volume110to be greater than the pressure of oil from oil source55.

In a hold position, when an electric current of a second magnitude is supplied to actuator102as shown inFIGS. 7A and 7B, actuator102urges valve spool30in a direction toward valve spring104thereby causing valve spring104to be compressed slightly more than in the retard position. In the hold position, supply land114is positioned to provide fluid communication between bolt supply passages74and spool annular supply groove116, thereby allowing pressurized oil to be supplied to phasing volume110through spool supply passages118a,118band supply check valve120from oil source55. Also in the hold position, lock pin land122is positioned to prevent fluid communication between bolt lock pin passages86and spool annular lock pin groove124, thereby preventing oil from being vented from lock pin bore66. Also in the hold position, lock pin land122is positioned to permit fluid communication between bolt lock pin passages86and phasing volume110, thereby allowing pressurized oil to be supplied to lock pin bore66via spool advance passage130, spool annular advance groove128, bolt lock pin passages86, bolt annular lock pin groove84, rotor annular lock pin groove88, and rotor lock pin passage72, and as a result, lock pin26compresses lock pin spring70and lock pin26is retracted from lock pin seat68. Also in the hold position, advance land131is positioned to block fluid communication between bolt advance passages92and spool annular vent groove132while simultaneously permitting restricted communication between bolt advance passages92and phasing volume110via spool annular advance groove128and spool advance passage130. Also in the hold position, retard land138is positioned to block fluid communication between bolt retard passages98and spool annular vent groove132while simultaneously permitting restricted fluid communication between bolt retard passages98and phasing volume110via spool annular retard groove140and spool retard passage142. By providing restricted fluid communication between bolt advance passages92and phasing volume110and between bolt retard passages98and phasing volume110while simultaneously blocking fluid communication between bolt advance passages92and spool annular vent groove132and between bolt retard passages98and spool annular vent groove132, the rotational position of rotor20and stator18is substantially maintained in the hold position. InFIG. 7B, the reference numbers have been removed for clarity and arrows representing the path of travel of the oil have been included where arrows S represent oil from oil source55which retracts lock pin26from lock pin seat68and which is supplied restrictingly to advance chambers42and retard chambers44. It should be noted thatFIG. 7Bshows supply check valve120being open, but may typically remain closed unless lock pin26is in the process of being retracted from lock pin seat68.

In an advance position, when an electric current of a third magnitude is supplied to actuator102as shown inFIGS. 8A and 8B, actuator102urges valve spool30in a direction toward valve spring104thereby causing valve spring104to be compressed slightly more than in the hold position until valve spool30abuts a second stop member150, which may be, by way of non-limiting example only, a shoulder formed in valve bore64. In the advance position, supply land114is positioned to provide fluid communication between bolt supply passages74and spool annular supply groove116, thereby allowing pressurized oil to be supplied to phasing volume110through spool supply passages118a,118band supply check valve120from oil source55. Also in the advance position, lock pin land122is positioned to prevent fluid communication between bolt lock pin passages86and spool annular lock pin groove124, thereby preventing oil from being vented from lock pin bore66. Also in the advance position, lock pin land122is positioned to permit fluid communication between bolt lock pin passages86and phasing volume110, thereby allowing pressurized oil to be supplied to lock pin bore66via spool advance passage130, spool annular advance groove128, bolt lock pin passages86, bolt annular lock pin groove84, rotor annular lock pin groove88, and rotor lock pin passage72, and as a result, lock pin26compresses lock pin spring70and lock pin26is retracted from lock pin seat68. Also in the advance position, advance land131is positioned to block fluid communication between phasing volume110and bolt advance passages92while simultaneously permitting fluid communication between bolt advance passages92and venting volume112via spool annular vent groove132, and spool vent passage134. Also in the advance position, retard land138is positioned to block fluid communication between bolt retard passages98and spool annular vent groove132while simultaneously permitting fluid communication between bolt retard passages98and phasing volume110via spool annular retard groove140and spool retard passage142. In this way, pressurized oil that is supplied to phasing volume110from oil source55is supplied to retard chambers44via spool retard passage142, spool annular retard groove140, bolt retard passages98, bolt annular retard groove96, rotor annular retard groove100, and rotor retard passages58while oil is simultaneously vented from advance chambers42via rotor advance passages56, rotor annular advance groove94, bolt advance passages92, spool annular vent groove132, spool vent passage134, venting volume112, and vent passages146, thereby causing rotor20to rotate relative to stator18to cause an advance in timing of camshaft14relative to the crankshaft. InFIG. 8B, the reference numbers have been removed for clarity and arrows representing the path of travel of the oil have been included where arrows S represent oil from oil source55that is supplied to retard chambers44and lock pin bore66and arrows V represent vented oil from advance chambers42. It should be noted thatFIG. 8Bshows supply check valve120being open, but supply check valve120may also be closed if a torque reversal acting on camshaft14causes the pressure within phasing volume110to be greater than the pressure of oil from oil source55.

Supply check valve120will now be described with particular reference toFIG. 13. Supply check valve120includes a first check valve member164and a second check valve member166such that first check valve member164is located within first phasing volume110aand second check valve member166is located within second phasing volume110band such that first check valve member164is diametrically opposed to second check valve member166within valve spool bore106. First check valve member164and second check valve member166are each arcuate in shape in order to match the curvature of valve spool bore106and are sized to selectively block respective spool supply passages118a,118b. Supply check valve120also includes a biasing section168which joins first check valve member164and second check valve member166. Biasing section168is resilient and compliant in order to bias first check valve member164and second check valve member166into contact with valve spool bore106while allowing first check valve member164and second check valve member166to be displaced inward under operating conditions as described previously which require flow into phasing volume110through spool supply passages118a,118b. Biasing section168includes a biasing section first leg168awhich extends axially from first check valve member164within first phasing volume110a, a biasing section second leg168bwhich extends axially from second check valve member166within second phasing volume110b, and a biasing section bridge168cwhich joins biasing section first leg168aand biasing section second leg168bsuch that biasing section bridge168cis axially spaced from first check valve member164and from second check valve member166. Biasing section bridge168cpasses between first phasing volume110aand second phasing volume110bthrough insert rib positioning notch158a. Biasing section bridge168cand insert rib positioning notch158aare sized to maintain the axial position of supply check valve120within phasing volume110to ensure that first check valve member164and second check valve member166are properly positioned to block respective spool supply passages118a,118bwhen first check valve member164and second check valve member166are biased into contact with valve spool bore106. It should be noted that when first check valve member164and second check valve member166are opened by oil pressure, first check valve member164and second check valve member166are each received within a respective insert first sidewall recess152c. As shown, supply check valve120may be a simple one-piece device that is made of formed sheet metal.

While camshaft phaser12has been described as defaulting to full advance, it should now be understood that camshaft phaser12may alternatively default to full retard by simply rearranging oil passages. Similarly, while full advance has been described as full counterclockwise rotation of rotor20within stator18as shown inFIG. 2, it should also now be understood that full advance may alternatively be full clockwise rotation of rotor20within stator18depending on whether camshaft phaser12is mounted to the front of internal combustion engine10(shown in the figures) or to the rear of internal combustion engine10.

While camshaft phaser attachment bolt28has been described herein as including grooves on the outer periphery thereof which are aligned with corresponding grooves formed in rotor central through bore40of rotor20, it should now be understood that the grooves on camshaft phaser attachment bolt28could be omitted and the grooves formed in rotor central through bore40could be used to serve the same function. Similarly, the grooves formed in rotor central through bore40could be omitted and the grooves on camshaft phaser attachment bolt28could be used to serve the same function.

Now with reference toFIGS. 15-20, an alternative valve spool200, insert300, and check valve400is illustrated in accordance with the present invention where valve spool200replaces valve spool30, insert300replaces insert108, and check valve400replaces supply check valve120. Valve spool200, insert300, and check valve400will be described in greater detail in the paragraphs that follow.

Valve spool200includes an outer peripheral surface202which is cylindrical and centered about axis of rotation16and which is sized to interface with valve bore64of camshaft phaser attachment bolt28is a close sliding fit which allows valve spool200to move axially within valve bore64of camshaft phaser attachment bolt28while substantially preventing oil from passing between the interface of outer peripheral surface202and valve bore64. Valve spool200extends from a valve spool first end204which is proximal to camshaft14to a valve spool second end206which is proximal to actuator102.

A valve spool bore208extends into valve spool200from valve spool first end204toward valve spool second end206such that valve spool bore208is centered about, and extends along, axis of rotation16. Valve spool bore208extends to a valve spool bore floor210which is traverse to axis of rotation16. Valve spool bore208includes a valve spool bore first portion208awhich extends from valve spool first end204toward valve spool second end206and also includes a valve spool bore second portion208bwhich extends from valve spool bore first portion208ato valve spool bore floor210. Valve spool bore second portion208bis smaller in diameter than valve spool bore first portion208a, thereby defining a valve spool bore shoulder208cwhere valve spool bore second portion208bmeets valve spool bore first portion208asuch that valve spool bore shoulder208cfaces toward valve spool first end204. A valve spool bore retention groove208dextends radially outward from valve spool bore first portion208asuch that valve spool bore retention groove208dis annular in shape and such that valve spool bore retention groove208dreceives an insert retainer212therein for retaining insert300within valve spool bore208as will be described in greater detail later. Insert retainer212is a split ring which is resilient and compliant, thereby allowing insert retainer212to be resiliently deflected to be decreased in diameter for insertion into valve spool bore first portion208aand then spring outward when aligned with valve spool bore retention groove208d. A valve spool first auxiliary bore208fand a valve spool second auxiliary bore208geach extend from valve spool bore floor210toward valve spool second end206such that valve spool first auxiliary bore208fand valve spool second auxiliary bore208gare each in constant fluid communication with valve spool bore208. Valve spool first auxiliary bore208fand valve spool second auxiliary bore208gare each laterally offset from, and parallel to, axis of rotation16such that valve spool first auxiliary bore208fand valve spool second auxiliary bore208gare diametrically opposed to each other and such that axis of rotation16does not pass through either of valve spool first auxiliary bore208fand valve spool second auxiliary bore208g. Finally, a valve spool bore insert clocking bore208hextends from valve spool bore floor210toward valve spool second end206such that valve spool bore insert clocking bore208his laterally offset from axis of rotation16and such that valve spool bore insert clocking bore208his used to orient insert300about axis of rotation16within valve spool bore208as will be describe in greater detail later.

Insert300extends from an insert first end302, which is proximal to valve spool first end204and which axially abuts insert retainer212, to an insert second end304, which is proximal to valve spool bore floor210. Insert300includes an insert first portion306at insert first end302which has an outer periphery which is sized to fit within valve spool bore first portion208aand which is sized to fit axially between valve spool bore shoulder208cand insert retainer212such that insert first portion306is centered about axis of rotation16. Insert300also includes an insert sealing bead308which is located within valve spool bore second portion208baxially between spool supply passages216and valve spool bore shoulder208c. Insert sealing bead308is annular in shape, centered about axis of rotation16, and is smaller in diameter than insert first portion306. Insert sealing bead308is spaced axially apart from insert first portion306by an insert groove310which is annular, centered about axis of rotation16, and smaller in diameter than insert sealing bead308. Insert sealing bead308is sized such that when insert sealing bead308is inserted into valve spool bore second portion208bin a direction from valve spool first end204toward valve spool second end206, the direction being illustrated by arrow312inFIG. 19, the outer periphery of insert sealing bead308is sheared off. The material of the outer periphery of insert sealing bead308that is sheared off is deposited in an annular chamber314that is formed radially between insert groove310and valve spool bore208where the portion of insert sealing bead308that is sheared off by insertion is illustrated by reference number316inFIG. 19. By allowing this material of insert sealing bead308to be sheared off, sealing engagement radially between insert sealing bead308and valve spool bore208is ensured by eliminating the potential for manufacturing variations to produce a gap, i.e. minimum material conditions, which would allow leakage. After the material has been sheared off of insert sealing bead308, insert sealing bead308is in sealing engagement with valve spool bore second portion208b, and in this way, insert300sealingly closes one end of valve spool bore208. It should be noted that the portion of insert sealing bead308that is to be sheared off is illustrated in phantom lines in the enlarged portion ofFIG. 19and is shown in solid lines in the remainder ofFIG. 19and inFIG. 20to show its initial condition.

The portion of insert300which is axially between insert sealing bead308and insert second end304is sized to accommodate and support check valve400radially between insert300and valve spool bore second portion208band includes a plurality of insert check valve travel limiters318which extend radially outward therefrom and are aligned with spool supply passages216. The function of insert check valve travel limiters318will be described in greater detail later. The portion of insert300which is axially between insert sealing bead308and insert second end304includes an insert first surface320which is traverse to axis of rotation16and also includes an insert second surface322which is traverse to axis of rotation16and faces toward insert first surface320, thereby defining an insert retention channel324axially between insert first surface320and insert second surface322which may be U-shaped as illustrated in the figures. Insert retention channel324is used to position and support check valve400as will be described in greater detail later.

An insert spring bore326extends into insert300from insert second end304in a direction which is parallel to axis of rotation16. Insert spring bore326is centered about an insert spring bore axis328which is parallel to, and laterally offset from, axis of rotation16, however, axis of rotation16does pass through insert spring bore326. Insert spring bore326is truncated by an insert spring bore end wall330which traverses insert spring bore axis328. An insert spring332is located within insert spring bore326and is held in compression against insert spring bore end wall330and valve spool bore floor210. In this way, insert spring332urges insert300toward, and holds insert300in compression against, insert retainer212. Insert spring332is selected to provide sufficient force to maintain insert300in compression against insert retainer212under all operating conditions of camshaft phaser12. A person of ordinary skill in the art would be able to select insert spring332to provide such sufficient force to maintain insert300in compression against insert retainer212through empirical testing, simulation, or calculations based on the pressure/vacuum/pulsation conditions that would be encountered within valve spool bore second portion208bduring operation which would tend to cause insert300to separate from insert retainer212if left unopposed.

Insert300also includes an insert alignment pin334which extends from insert second end304into valve spool bore insert clocking bore208h. Insert alignment pin334is eccentric to axis of rotation16, and consequently, insert alignment pin334orients insert300within valve spool bore208and prevents rotation of insert300within valve spool bore208about axis of rotation16.

Check valve400is made of a single piece of sheet metal which is stamped and formed to include the features which will now be described. Check valve400is carried by insert300and includes a check valve base402which is U-shaped and received within insert retention channel324. Check valve base402includes a first leg402a, a second leg402bspaced laterally from first leg402a, and a bridge402cwhich joins one end of first leg402awith one leg of second leg402b. Check valve400also includes a first check valve member404and a second check valve member406which are diametrically opposed to each other and contoured to be complementary to valve spool bore second portion208b. First check valve member404and second check valve member406are each aligned with a respective spool supply passage216and are sized to selectively block spool supply passages216, thereby preventing oil from flowing out of valve spool bore208through spool supply passages216. First check valve member404is connected to first leg402aby a first arm408which is resilient and compliant such that first arm408biases first check valve member404into a seated position against valve spool200, thereby blocking a respective spool supply passage216. Similarly, second check valve member406is connected to second leg402bby a second arm410which his resilient and compliant such that second arm410biases second check valve member406into a seated position against valve spool200, thereby blocking a respective spool supply passage216.

In order to fix check valve400in position on insert300, check valve400includes a plurality of check valve retention members412extending from check valve base402. As illustrated herein, four check valve retention members412may be provided such that first leg402aincludes two check valve retention members412, one on each side of first arm408, and such that second leg402bincludes two check valve retention members412, one on each side of second arm410, however, a lesser number or a greater number of check valve retention members412may be provided on check valve base402. Check valve retention members412are open-ended loops which are resilient and compliant such that check valve retention members412are located within insert retention channel324and are held in compression against insert first surface320, thereby compressing check valve base402against insert second surface322and retaining check valve400to insert300. It should be noted thatFIG. 20illustrates first check valve member404and second check valve member406in solid lines in the seated position and also illustrates first check valve member404and second check valve member406in phantom lines in an unseated position which permits flow into valve spool bore208when a pressure differential causes first check valve member404and second check valve member406to resiliently flex first arm408and second arm410respectively. As shown inFIG. 20, travel of first check valve member404and second check valve member406is limited by insert check valve travel limiters318.

Valve spool200, insert300, and check valve400as described herein allows for simplified construction of camshaft phaser12compared to the prior art and ensures that check valve400is supported by insert300while minimizing sliding contact between check valve400and insert300, thereby minimizing wear. Additionally, inclusion of annular chamber314allows for a portion of insert sealing bead308to be sheared off which ensures sealing in the radial direction between insert sealing bead308and valve spool200. Also additionally, including insert spring332ensures that insert300and check valve400remain static in the pulsed pressure environment within valve spool200.

While valve spool200, insert300, and check valve400have been illustrated herein as being applied to an oil pressure actuated camshaft phaser, it should be understood that some features may be equally applicable to cam torque actuated camshaft phasers which utilize torque reversals of the camshaft to move oil directly from the advance chambers to the retard chambers or to move oil directly from the retard chambers to the advance chambers to change the phase relationship. One such cam torque actuated camshaft phaser is described in U.S. Pat. No. 9,587,526 to Lichti et al., the disclosure of which is incorporated herein by reference in its entirety.

While this invention has been described in terms of preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.