Valve operating system providing variable valve lift and/or variable valve timing

A valve operating system that includes a plurality of cam assemblies that are coupled for rotation about a rotary axis. Each of the cam assemblies has a control link and a first cam member. Each of the control links has a link body, which forms a majority of the control link, and that extends parallel to the rotary axis. Each of the first cam members is coupled to one of the control links for axial movement therewith along the rotary axis between first and second positions to alternate between first and second cam profiles, respectively.

FIELD

The present disclosure relates to a valve operating system that provides variable valve lift and/or variable valve timing.

BACKGROUND

Modern automotive four-stroke internal combustion engine are typically configured with intake and exhaust valves that can be selectively opened via a valve operating system to intake air or an air-fuel mixture into the engine cylinders and to exhaust gasses from the engine cylinders. A valve operating system with a camshaft is commonly employed to control the timing and duration of the opening of the several valves. The camshaft typically includes several cam lobes, with each of the cam lobes having a shape that determines the duration that one or more associated valves are opened, as well as the amount by which the one or more associated valves are opened. It will be appreciated, too, that the position of an associated one of the cam lobes about the rotary axis of the camshaft determines the timing or phase of the opening of the one or more associated valves. The combination of the shape and phase of a cam lobe will be referred to herein as “cam profile”.

The operation of such internal combustion engines are greatly affected by the timing and duration of the opening of the intake valves and the exhaust valves and as such, it is known in the art to configure a camshaft with multiple sets of cam lobes that can be employed on an alternative basis to provide variable valve lift and/or variable valve timing. While such valve operating systems are suited for their intended purpose, they are nevertheless susceptible to improvement.

SUMMARY

In one form, the present teachings provide a valve operating system that includes a plurality of cam assemblies. The cam assemblies are coupled for rotation about a rotary axis. Each of the cam assemblies has a control link and a first cam member. Each of the control links has a link body, which forms a majority of the control link, and that extends parallel to the rotary axis. Each of the first cam members is coupled to a corresponding one of the control links for axial movement therewith along the rotary axis. Each of the first cam members has a first cam configuration, which has a first predetermined lift profile, and a second cam configuration that has a second predetermined lift profile that is different from the first predetermined lift profile. Each of the cam assemblies is slide-able along the rotary axis between a first position, in which the first cam configurations are positioned in associated activated locations and each of the second cam configurations is offset along the rotary axis from their associated activated location, and a second position, in which the second cam configurations are positioned in the associated activated locations and each of the first cam configurations is offset along the rotary axis from their associated activated location.

The first cam members can be axially slidably coupled to a cam tube and the link bodies are received in the cam tube. Optionally, the first cam members can be non-rotatably coupled to the cam tube. Each of the first cam members can define a plurality of internal teeth that can meshingly engage a plurality of external teeth on the cam tube. Each of the cam assemblies can further include a detent mechanism that is configured to releasably secure the first cam members to the cam tube. Optionally, each of the detent mechanisms can include first and second recesses formed in the cam tube, a detent member received in a hole in an associated one of the first cam members, and a band spring that is received about the associated one of the first cam members. The band spring can urge the detent member toward the cam tube and can limit movement of the detent member relative to the associated one of the first cam members in a radially outward direction from the cam tube. Receipt of the detent member into the first recess releasably secures an associated one of the cam assemblies in the first position, while receipt of the detent member into the second recess releasably secures the associated one of the cam assemblies in the second position. The detent member can optionally be a spherical ball.

The valve operating system can optionally include a spacer that is received within the cam tube and which forms a plurality of link slots. Each of the control links can be received in a corresponding one of the link slots. Optionally, a lateral cross-section of the spacer taken perpendicular to the rotary axis can be X-shaped or Y-shaped.

Each of the cam assemblies can further include a second cam member that is coupled to an associated one of the control links for axial movement therewith along the rotary axis. The second cam member is spaced apart axially along the rotary axis from the first cam member.

Each of the control links can further include an engagement member that extends radially outwardly from the link body and engages a corresponding one of the first cam members. The engagement member can be a discrete component that is assembled to the link body, for example by welding.

Each of the first cam members can optionally have a third cam configuration with a third predetermined lift profile. The third predetermined lift profile of at least a portion of the third cam configurations can be different from the first predetermined lift profile and the second predetermined lift profile. Each of the cam assemblies is slide-able along the rotary axis to a third position that is intermediate the first and second positions. Placement of the cam assemblies into their third position in which the third cam configurations are positioned in the associated activated locations and each of the first and second cam configurations is offset along the rotary axis from the associated activated locations.

The second predetermined lift profile differs from the first predetermined lift profile in at least one of a value of maximum lift and a rotational timing of the value of maximum lift.

In another form, the present teachings provide a valve operating system that includes a cam tube, which is rotatable about a rotary axis, a plurality of cam assemblies and a plurality of actuator segments. The cam assemblies are coupled for rotation about a rotary axis. Each of the cam assemblies has a control link and a first cam member. Each of the control links has a link body, which forms a majority of the control link, and that extends parallel to the rotary axis. Each of the first cam members is coupled to a corresponding one of the control links for axial movement therewith along the rotary axis. Each of the first cam members has a first cam configuration, which has a first predetermined lift profile, and a second cam configuration that has a second predetermined lift profile that is different from the first predetermined lift profile. Each of the cam assemblies is slide-able along the rotary axis between a first position, in which the first cam configurations are positioned in associated activated locations and each of the second cam configurations is offset along the rotary axis from their associated activated location, and a second position, in which the second cam configurations are positioned in the associated activated locations and each of the first cam configurations is offset along the rotary axis from their associated activated location. Each of the actuator segments is non-rotatably but axially slidably coupled to the cam tube and axially fixed to an associated one of the control links. Each of the actuator segments defines first and second ramp profiles that extend in a circumferential direction about the actuator segment. The first ramp profile has a first ramp section and a second ramp section that is offset axially along the rotary axis from the first ramp section. The second ramp profile has a third ramp section and a fourth ramp section that is offset axially along the rotary axis from the third ramp section.

The first ramp profile can be formed by a first groove and the second ramp profile can be formed by a second groove that is spaced axially apart from the first groove along the rotary axis. The valve operating system can further include a first pin that is selectively engagable to the first ramp profile and a second pin that is selectively engagable to the second ramp profile. Each of the first and second pins can have a longitudinal axis that is disposed perpendicular to the rotary axis. The valve operating system can further include a first solenoid, which is selectively operable for translating the first pin radially toward the rotary axis, and a second solenoid that is selectively operable for translating the second pin radially toward the rotary axis.

The first ramp profile of at least one of the actuator segments can optionally include an engagement section. The second ramp section can be disposed between the first transition section and the engagement section. A portion of the first groove that forms the engagement section can have a bottom wall that tapers radially inwardly with increasing circumferential distance from the second ramp portion. The engagement section can be configured to receive the first pin without contact between the first pin and the engagement section causing movement of the at least one of the actuator segments along the rotary axis.

The first and second ramp profiles can be formed by a common groove. The first and second ramp profiles can be spaced axially apart from one another. The valve operating system can include at least one pin that is selectively engagable to the first ramp profile and the second ramp profile. The at least one pin has a longitudinal axis that is disposed perpendicular to the rotary axis. The valve operating system can further include at least one solenoid that is selectively operable for translating the at least one pin into engagement with the first ramp profile on the actuator segments. The at least one solenoid can be configured to translate the at least one pin parallel to the rotary axis.

The cam tube can define a plurality of arm members onto which the actuator segments are non-rotatably and axially slidably mounted. Optionally, the arm members number two in quantity.

The valve operating system can further include at least one pin that is selectively engagable to the first and second ramp profiles.

The first and second ramp profiles can be different from one another so as not to have reflection symmetry about a plane that is perpendicular to the rotary axis and equidistant from the first and second ramp profiles. For example, the first ramp profile can have a first transition section that is disposed between the first ramp section and the second ramp section, the second ramp profile can have a second transition section that is disposed between the third ramp section and the fourth ramp section, and the first and second intermediate sections can be configured so that they are not mirror images of one another.

DETAILED DESCRIPTION

With reference toFIGS. 1 and 2, a portion of an internal combustion engine is illustrated as having a valve operating system10constructed in accordance with the teachings of the present disclosure. The internal combustion engine in the particular example illustrated is a four cylinder overhead cam engine with an in-line cylinder configuration, but it will be appreciated that the teachings of the present disclosure have application to other engine configurations and as such, it will be understood that the scope of the present disclosure is not limited to engines with an overhead cam engines or to engines with an in-line cylinder configuration. The engine can include a cylinder head CH and a drive means DM for providing rotary power to drive the valve operating system10, such as a cam gear, cam sprocket or cam pulley. Except as otherwise noted herein, the cylinder head CH and drive means DM can be configured in a well-known and conventional manner. The valve operating system10can include a cam tube12, a plurality of cam assemblies14and an actuator16.

With reference toFIGS. 2 and 3, the cam tube12can be coupled to the drive means DM to receive rotary power therefrom. In the example provided, the cam tube12is fixedly and non-rotatably coupled to the drive means DM, but it will be appreciated that a variable coupling could be employed to couple the cam tube12to the drive means DM to selectively alter the rotational position of the cam tube12relative to the drive means DM within a predetermined range to provide the valve operating system10with variable valve timing capabilities. The cam tube12can have a hollow interior20and can define a plurality of cam member mounts22and a plurality of journals24. The journals24can be received in a cam bore CB that can be formed between the cylinder head CH and a plurality of cam caps CC that are fixedly but removably coupled to the cylinder head CH. A plurality of bearings (not specifically shown) can be disposed between the journals24and the cylinder head CH and the cam caps CC so that the cam tube12is supported relative to the cylinder head CH for rotation about a rotary axis28.

InFIGS. 2 and 4, each of the cam assemblies14can include a control link30and one or more cam members32. The control links30can have a link body36and one or more engagement members38. The link body36can form a majority of the control link30and can extend within the hollow interior20of the cam tube12along the rotary axis28(i.e., parallel to the rotary axis28). Each of the engagement members38can be coupled to the link body36for translation with the link body36along the rotary axis28and can extend radially outwardly from the link body36. In the example provided, a first one of the engagement members38ais formed of a component that is assembled to the link body36and secured together with a suitable coupling means, such as a weld and/or fasteners, while a second one of the engagement members38bis unitarily and integrally formed with the link body36(e.g., as a hook or projection that extends perpendicular to the link body36). It will be appreciated, however, that all of the engagement members38could be discrete components that are assembled and secured to the link body36or that all of the engagement members38could be unitarily and integrally formed with the link body36, for example through bending, cold heading or forging.

Each of the cam members32can be axially slidably but non-rotatably coupled to the cam tube12. In the example provided, each of the cam members32has an internally splined or toothed aperture40and is received over the cam tube12such that the internal teeth of the internally splined aperture40meshingly engage corresponding external teeth formed on the cam member mounts22on the cam tube12.

Each of the cam members32can have a first cam configuration50and a second cam configuration52that are employed on an alternate basis to open a set of valves (not shown). Depending on the configuration of the engine, the set of valves may comprise solely one or more intake valves, or may comprise solely one or more exhaust valves, or may comprise both one or more intake valves and one or more exhaust valves. The first cam configuration50can have a first predetermined lift profile, while the second cam configuration52can have a second predetermined lift profile that is different from the first predetermined lift profile. With reference toFIG. 5, the first predetermined lift profile could include one or more first cam lobes56that are configured to provide a first maximum lift value L1(i.e., the maximum radius of the first cam lobe56minus the radius R of the base circle BC of the first cam lobe56), while the second predetermined lift profile could include one or more second cam lobes58that are configured to provide a second maximum lift value L2that is different from the first maximum lift value L1. In situations where the first and second cam configurations50and52are configured to open a set of valves that comprises both one or more intake valves and one or more exhaust valves, it will be appreciated that the first and second cam lobes56and58(FIG. 5) mentioned previously are configured to open either the intake valve(s) or the exhaust valve(s), and that the first and second cam configurations50and52will additionally include one or more other cam lobes (not shown) that are configured to open the other type of valves (i.e., exhaust valves or intake valves) that are not opened by the first and second cam lobes56and58(FIG. 5). Additionally or alternatively, the first cam lobes56of the first predetermined lift profile could be timed (i.e., oriented about the rotary axis) differently from the second cam lobes58of the second predetermined lift profile as shown inFIG. 6and as represented by the angle A.

With reference toFIGS. 2 and 3, each of the cam members32of a given one of the cam assemblies14can be coupled to the control link30of the given one of the cam assemblies14for axial movement with the control link30along the rotary axis28. In the example provided, each of the engagement members38of the control links30are received through respective slotted apertures60(best shown inFIG. 3) formed in the cam tube12and are received into (and optionally through) respective apertures62formed in a respective one of the cam members32.

Each of the cam assemblies14is slide-able along the rotary axis28between a first position (FIG. 7), in which the first cam configurations50are positioned in associated activated locations70and each of the second cam configurations52is offset along the rotary axis28from their associated activated location70, and a second position (FIG. 8), in which the second cam configurations52are positioned in the associated activated locations70and each of the first cam configurations50is offset along the rotary axis28from their associated activated location70.

Returning toFIGS. 2 and 4, each of the cam assemblies14can optionally include one or more detent mechanisms74that can be configured to releasably secure one or more of the cam members32to the cam tube12. In the example provided, each of the detent mechanisms74includes first and second recesses80and82(best shown inFIG. 3), respectively, formed in the cam tube12, a detent member84that is received in a hole86(best shown inFIG. 3) in an associated one of the cam members32, and a band spring88that is received about the associated one of the cam members32. The detent member84can be a spherical ball. The band spring88can be received about an associated one of the cam members32and can urge the detent member84toward the cam tube12, as well as limit movement of the detent member84relative to the associated one of the cam members32in a radially outward direction from the cam tube12. Receipt of the detent member84into the first recess80(FIG. 3) releasably secures the associated one of the cam members32to the cam tube12such that an associated one of the cam assemblies14is releasably maintained in the first position. Similarly, receipt of the detent member84into the second recess82(FIG. 3) releasably secures the associated one of the cam members32to the cam tube12such that the associated one of the cam assemblies14is maintained in the second position.

With reference toFIGS. 2 and 9, a spacer90can optionally be received within the hollow interior20of the cam tube12to separate the control links30from one another. In the particular example provided, the spacer90has a cylindrical body92, which is sized to be received into the hollow interior20of the cam tube12. A plurality of grooves94are formed into the cylindrical body92and intersect the outside diametrical surface of the cylindrical body92. The grooves94can be spaced circumferentially about the cylindrical body92in a symmetrical manner and can be shaped to accommodate the link bodies36of the control links30. In the example provided, the link bodies36are formed from a rod having a circular (lateral) cross-sectional shape and each of the grooves94is generally U-shaped. Each of the link bodies36can be received into a corresponding one of the grooves94. It will be appreciated that the spacer90could be formed somewhat differently. For example, the spacer90athat is depicted inFIG. 10has a cross-sectional shape (taken laterally in a manner that is perpendicular to the rotary axis28) that is generally Y-shaped, whereas the spacer90bthat is depicted inFIG. 11has a cross-sectional shape (taken laterally perpendicular to the rotary axis28that is generally X-shaped. It will be appreciated that the embodiment ofFIG. 10depicts a portion of valve operating system for a six cylinder, overhead cam engine with a “V” configuration that employs three cam assemblies on each bank of the engine.

It will be appreciated that the present disclosure is not limited to valve operating systems having cam members with only two different cam configurations but rather can include multiple cam configurations. In the example ofFIG. 12, the valve operating system10aincludes cam members32ahaving a third cam configuration100with a third predetermined lift profile. The third predetermined lift profiles of at least a portion of the third cam configurations100can be different from the first predetermined lift profile and the second predetermined lift profile. In the particular example provided, each of the third cam configurations has a third predetermined lift profile that is different from the first and second predetermined lift profiles. It will be appreciated, however, that one or more of the third cam configurations can have a third predetermined lift profile that is different from the first and second predetermined lift profiles and configured to provide cylinder de-activation, while a remaining one or more of the third cam configurations can have a third predetermined lift profile that is identical to one of the first and second lift profiles. Configuration in this latter manner permits some cylinders to be deactivated while the remaining cylinders remain active. Each of the cam assemblies14ais slide-able along the rotary axis28to a third position that is intermediate the first and second positions. Placement of the cam assemblies14ainto their third position correspondingly places the third cam configurations100in the associated activated locations and correspondingly places each of the first and second cam configurations50and52at locations that are offset along the rotary axis28from the associated activated locations.

With reference toFIGS. 2 and 3, the actuator16can include a plurality of actuator segments110and one or more pins112that can selectively interact with the actuator segments110to coordinate axial movement of the cam assemblies14along the rotary axis28.

With reference toFIGS. 13 and 14, the actuator segments110can be generally shaped as an annular segment, and when collectively aligned to one another, the actuator segments110can form a generally annular (but segmented) structure. Each of the actuator segments110can be non-rotatably but axially slidably coupled to the cam tube12and can be axially fixed to an associated one of the control links30. In the example provided, a pair of slots120is formed into an end of the cam tube12opposite the drive means DM (FIG. 2) to form a pair of arm members122. It will be appreciated that while the slots120are depicted as extending through an axial end of the cam tube12(so that the slots120are open on one end), the slots120could be formed inward from the axial ends of the cam tube12so that the slots are closed on their opposite axial ends. Each of the actuator segments110is configured with a pair of circumferentially-extending slots130that are sized to receive corresponding portions of the arm members122. Receipt of the arm members122into the circumferentially-extending slots130inhibits rotation of the actuator segments110relative to the cam tube12while permitting the actuator segments110to slide on the cam tube12.

The link body36of each control link30can be coupled to a corresponding one of the actuator segments110in any desired manner. In the particular example provided, a through-hole136is formed in each of the actuator segments110and each of the link bodies36is received into the through-hole136and engaged in a press-fit manner to a corresponding one of the actuator segments110. It will be appreciated that other coupling means, such as threads, clips, fasteners and/or flanges (e.g., formed via upsetting) that are coupled to or integrally formed with the link bodies36, could be employed to secure the control links30to the actuator segments110.

Each of the actuator segments110can define first and second ramp profiles150and152, respectively, that can extend in a circumferential direction about the actuator segment110. Each of the first ramp profiles150on the actuator segments110can (but need not) be configured in an identical manner. Each of the second ramp profiles152on the actuator segments110can (but need not) be configured in an identical manner. In the example provided, the first ramp profile150is formed by a first groove154that is formed on a given one of the actuator segments110, and the second ramp profile152is formed by a second groove156that is formed on the given one of the actuator segments110and spaced axially apart from the first groove154along the rotary axis28. The first and second grooves154and156are disposed on opposite sides of a land160, and the first and second ramp profiles150and152are formed on the opposite sidewalls of the land160(i.e., the edges of the first and second grooves154and156, respectively, that form the land160). The first ramp profile150can have a first ramp section170, a second ramp section172that is offset axially along the rotary axis28from the first ramp section170, and a first transition section174that is shaped “helically” about the rotary axis28and connects the first and second ramp sections170and172. The second ramp section172can be relatively short and in an extreme case, consists of a single point at an end of the first transition section174that is opposite the first ramp section170. The second ramp profile152can have a third ramp section180, a fourth ramp section182that is offset axially along the rotary axis28from the third ramp section180, and a second transition section184that is shaped helically about the rotary axis28and connects the third and fourth ramp sections180and182. The fourth ramp section182can be relatively short and in an extreme case, consists of a single point at an end of the second transition section184that is opposite the third ramp section180. The second ramp profile152can be a mirror image of the first ramp profile150.

It will be appreciated that the first and second transition sections174and184can be shaped in any desired manner. For example, the first transition section174and the second transition section184could be configured so that as a function of the location about the circumferential surface of the actuator segment, the surface of the first or second transition section varies in a constant manner (i.e. the surface is formed as a true helix) or in a multi-staged manner, such as at an initially slower rate (e.g., to limit the axial force generated by movement of the associated cam assembly), and/or ending at a slower rate (e.g., to decelerate the associated cam assembly so as to prevent the associated one of the cam assemblies from over-traveling).

The actuator segments110are configured such that the first and third ramp sections170and180are disposed on one circumferential end of the actuator segment110and that the second and fourth ramp sections172and182are disposed on an opposite circumferential end of the actuator segment110. When mounted on the cam tube12, the actuator segments110are arranged relative to one another so that the circumferential end of one actuator segment110having the second and fourth ramp sections172and182is abutted against the circumferential end of another actuator segment110having the first and third ramp sections170and180.

With reference toFIGS. 2, 15 and 17, the actuator16in the example provided comprises a pair of pins112(i.e., a first pin112aand a second pin112b) that are selectively engagable to the first and second ramp profiles150and152, respectively. Each of the first and second pins112aand112bcan have a longitudinal axis200that can be disposed perpendicular to the rotary axis28. The first pin112acan be selectively translated toward the rotary axis28into engagement with the first ramp profile150to coordinate movement of the cam assemblies14from their first position to their second position. Similarly, the second pin112bcan be selectively translated toward the rotary axis28into engagement with the second ramp profile152to coordinate movement of the cam assemblies14from their second position to their first position. Any desired means can be employed to selectively translate the first pin112aand the second pin112b. In the example provided, a first solenoid206is employed to translate the first pin112a, while a second solenoid208is employed to translate the second pin112b. Each of the first and second solenoids206and208can have a plunger (not specifically shown) that can be coupled to the first pin112aor second pin112bfor common translating motion, an electromagnetic coil (not shown) that can be energized to drive the plunger and the first pin112aor the second pin112btoward the rotary axis28, and a spring (not shown) that can bias the plunger and the first pin112aor second pin112baway from the rotary axis28.

With reference toFIGS. 2 and 15, during operation of the engine and rotation of the cam assemblies14, the actuator16can be selectively operated to translate the cam members32along the rotary axis28to locate a desired one of the cam configurations on each of the cam members32at an associated activated location70(FIG. 7) so that the desired cam configurations on each of the cam members32is employed to open corresponding sets of valves. With the cam assemblies14in their first positions so that the first cam configurations50(FIG. 5) are disposed in the associated activated locations70(FIG. 7), the first solenoid206can be operated to drive the first pin112atoward the rotary axis28such that the first pin112ais engagable to the first ramp profile150. Rotation of the actuator segments110via the drive member DM causes the first pin112ato “ride” along the first ramp profile150. Contact between the first pin112aand the first transition section174on a first one of the actuator segments110urges the first one of the actuator segments110(and an associated one of the cam assemblies14) in a first direction axially along the rotary axis28. Movement of the associated one of the cam assemblies14out of the first position causes the detent member84(FIG. 3) that is carried in one or more of the associated cam members32to disengage the first recess80(FIG. 3) on the cam tube12. Translation of the first one of the actuator segments110and its associated cam assembly14in the first direction along the rotary axis terminates when the first pin112acontacts the second ramp section172, at which point the associated one of the cam assemblies14is disposed in its second position so that the second cam configurations52(FIG. 5) on the cam members32of the associated one of the cam assemblies14are disposed in their associated activated locations70(FIG. 8). In this position, the detent member84that is carried in one or more of the associated cam members32is received in the second recess82(FIG. 3) in the cam tube12to resist movement of the associated one of the cam assemblies14along the rotary axis28from its second position.

It will be appreciated that continued rotation of the drive member DM causes each of the remaining actuator segments110(and their associated cam assembly14) to be similarly translated along the rotary axis28to position the remaining cam assemblies14in their second positions so that all of the cam members32are positioned along the cam tube12such that the second cam configurations52are positioned in their associated activated locations70.

With reference toFIGS. 2 and 16, during operation of the engine and with the cam assemblies14in their second positions so that the second cam configurations52(FIG. 5) are disposed in the associated activated locations70(FIG. 8), the second solenoid208can be operated to drive the second pin112btoward the rotary axis28such that the second pin112bis engagable to the second ramp profile152. Rotation of the actuator segments110via the drive member DM causes the second pin112bto “ride” along the second ramp profile152. Contact between the second pin112band the second transition section184on a first one of the actuator segments110urges the first one of the actuator segments110(and an associated one of the cam assemblies14) in a second direction along the rotary axis28that is opposite the first direction. Translation of the first one of the actuator segments110and its associated cam assembly14in the second direction along the rotary axis28terminates when the second pin112bcontacts the fourth ramp section182, at which point the associated one of the cam assemblies14is disposed in its first position so that the first cam configurations50on the cam members32of the associated one of the cam assemblies14are disposed in their associated activated locations70. It will be appreciated that continued rotation of the drive member DM causes each of the remaining actuator segments110(and their associated cam assembly14) to be similarly translated along the rotary axis28to position the remaining cam assemblies14in their first positions so that all of the cam members32are positioned along the cam tube12such that the first cam configurations50are positioned in their associated activated locations70.

InFIG. 17, a portion of another valve operating system constructed in accordance with the teachings of the present disclosure is illustrated. In this example, each of the first and second ramp profiles150aand152a, respectively, includes an engagement section300that is configured to intersect the first and second grooves154aand156a, respectively, on an adjacent one of the actuator segments110a. The engagement section300that is disposed in-line with the first groove154ais disposed on a circumferential side of the second ramp section172that is opposite the first transition section174and tapers radially inwardly with increasing circumferential distance from the first transition section174. Similarly, the engagement section300that is disposed in-line with the second groove156is disposed on a circumferential side of the fourth ramp section182that is opposite the second transition section184and tapers radially inwardly with increasing circumferential distance from the second transition section184. Each engagement portion300is configured to permit “early” contact between the actuator segment110dand an associated one of the first and second pins112aand112b. For example, the first pin112acan be translated toward the rotary axis28and can contact the engagement section300on a first one of the actuator segments110dso as to be fully seated when the first pin112aengages the first transition section170on a next one of the actuator segments110a. Given the rotational speed of the camshaft of a conventional engine, which can vary between 300 rotations per minute to 3500 rotations per minute, the presence of the engagement section300on one or more of the actuator segments110aeffectively lengthens the first and third ramp sections170and180so that additional time is provided for a respective one of the first and second pins112aand112bto extend fully before the first pin112acontacts the first transition section174or the second pin112bcontacts the second transition section184.

It will also be appreciated that there are various times at which the camshaft of an internal combustion engine is able to rotate in a reverse direction, such as when the internal combustion engine has been shut down while a rotary load has been applied to the crankshaft that tends to rotate the crankshaft in a rotational direction opposite the rotational direction it would rotate when the internal combustion engine is running. In such cases, the actuator segments110acould damage any of the pins112a,112bthat would be driven into contact with the second ramp section172or fourth ramp section182of an actuator segment110aas the actuator segments110aare rotated in the opposite rotational direction. The engagement sections300, however, help to guard against damage to the pins112a,112bin such situations by causing the pins112a,112bto lift onto the actuator segment110aas the actuator segment110ais rotated in its opposite rotational direction.

InFIG. 18, a portion of still another valve operating system constructed in accordance with the teachings of the present disclosure is illustrated. In this example, the actuator segments110bare formed via a single groove400, with the first and second ramp profiles150and152be formed on the opposite sidewalls of the single groove400. If desired, the first and second ramp profiles150and152can be spaced axially apart from one another along the rotary axis28. If desired, a single pin112can be selectively employed to engage the first and second ramp profiles150and152to coordinate movement of the actuator segments110balong the rotary axis28. The single pin112can be maintained within the single groove400with its longitudinal axis200being perpendicular to the rotary axis28and can be translated along the rotary axis28via a solenoid402to alternately contact the first ramp profile150and the second ramp profile152.

In the example provided, the single pin112is movable along the rotary axis28between a first pin position410, a second position412and a third or intermediate position414that is disposed between the first and second positions410and412. With the drive member DM (FIG. 2) rotating and the actuator segments110bin their first positions, the cam assemblies14(FIG. 2) can be disposed along the rotary axis28in their first positions so that the first cam configurations50(FIG. 5) are positioned in the associated activated locations. When the single pin112is placed in the intermediate pin position414, the single pin112can contact the first ramp profile150of the actuator segments110bas they rotate about the rotary axis28, which can drive the actuator segments110band the cam assemblies14(FIG. 2) in the first direction along the rotary axis28so that the cam assemblies14(FIG. 2) can be disposed along the rotary axis28in third positions that are intermediate the first and second positions so that third cam configurations on the cam members are positioned in the associated activated locations. When the single pin112is moved further to the second pin position, the single pin112can contact the first ramp profile150of the actuator segments110bas they rotate about the rotary axis28, which can drive the actuator segments110band the cam assemblies14(FIG. 2) in the first direction along the rotary axis28so that the cam assemblies14(FIG. 2) can be disposed along the rotary axis28in the second positions so that the second cam configurations on the cam members are positioned in the associated activated locations.

Thereafter, the single pin112can first be moved from the second position to the intermediate position to contact the second ramp profile152on the actuator segments110bto translate the cam assemblies to their intermediate positions, and thereafter the single pin112can be moved from the intermediate position414to the first position410to contact the second ramp profile152on the actuator segments110bto translate the cam assemblies to their first positions.

The example ofFIGS. 19 through 21, another valve operating system10cis illustrated. The valve operating system10cis generally identical to that ofFIG. 1, except that the valve operating system10cincludes a variable valve timing mechanism500and the cam tube12is non-rotatably coupled to a rotor502of the variable valve timing mechanism500. It will be appreciated that the rotor502of the variable valve timing mechanism500is pivotable about the drive means DM to vary the rotational position of the cam members32relative to the drive means DM.