WO2017091799A1

WO2017091799A1 - Rocker arm assembly having an electrical connection made between abutting surfaces that undergo relative motion

Info

Publication number: WO2017091799A1
Application number: PCT/US2016/063730
Authority: WO
Inventors: Tomas DRABEK; Petr LISKAR; James Edward Mccarthy, Jr.; Robert Philip Benjey; Austin Robert Zurface; Eric John YANKOVIC; Anthony Leon Spoor; Brian Karl Vandeusen; Nicholas GILLETTE; Thomas Michael TEMBREULL; Michael James STANTON
Original assignee: Eaton Corporation
Priority date: 2015-11-25
Filing date: 2016-11-24
Publication date: 2017-06-01

Abstract

A valvetrain for an internal combustion engine of the type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, and a camshaft includes a rocker arm assembly, a pivot providing a fulcrum for a rocker arm of the rocker arm assembly, and a latch assembly. An electrical device mounted to the rocker arm assembly receives power or communicates through a circuit that includes an electrical connection formed by abutment between surfaces of two distinct parts. The rocker arm assembly is operative to move one of the two abutting surfaces relative to the other in response to actuation of the cam follower. Forming an electrical connection through abutting surfaces that are free to undergo relative motion may reduce or eliminate the need to run wires to a mobile portion of the rocker arm assembly.

Description

ROCKER ARM ASSEMBLY HAVING AN ELECTRICAL CONNECTION MADE BETWEEN ABUTTING SURFACES THAT UNDERGO RELATIVE MOTION

Field

[0001] The present teachings relate to valvetrains, particularly valvetrains providing variable valve lift (VVL) or cylinder deactivation (CDA).

Priority

[0002] The present application claims priority from US Provisional Patent Application No. 62/259,764 filed November 25, 2015 and US Provisional Patent Application No. 62/305,612 filed March 9, 2016.

Background

[0003] Hydraulically actuated latches are used on some rocker arm assemblies to implement variable valve lift (VVL) or cylinder deactivation (CDA). For example, some switching roller finger followers (SRFF) use hydraulically actuated latches. In these systems, pressurized oil from an oil pump may be used for latch actuation. The flow of pressurized oil may be regulated by an oil control valve (OCV) under the supervision of an engine control unit (ECU). A separate feed from the same source provides oil for hydraulic lash adjustment. In these systems, each rocker arm assembly has two hydraulic feeds, which entails a degree of complexity and equipment cost.

[0004] The oil demands of these hydraulic feeds may approach the limits of existing supply systems. The complexity and demands for oil in some valvetrain systems can be reduced by replacing hydraulically latched rocker arm assemblies with electrically latched rocker arm assemblies. Electrically latched rocker arm assemblies require power.

Summary

[0005] The present teachings relate to powering or communicating with an electronic device such as a solenoid that is mounted to a mobile portion of a rocker arm assembly such as a rocker arm. If the electronic device is powered with conventional wiring, it is a possible for a wire to be caught, clipped, or fatigued and consequently short out.

[0006] The present teachings relate to a valvetrain suitable for an internal combustion engine that includes a combustion chamber, a moveable valve having a seat formed within the combustion chamber, and a camshaft. The valvetrain includes a rocker arm assembly. The rocker arm assembly includes a rocker arm, a cam follower configured to engage a camshaft- mounted cam as the camshaft rotates, and an electrical device mounted to the rocker arm. [0007] According to some aspects of the present teachings, an electrical circuit that includes the electrical device includes a connection formed by abutment between the surfaces of two distinct parts. The rocker arm assembly is operative to move one of the parts

independently from the other in response to actuation of the cam follower. The abutting surfaces of the two distinct parts may be electrically isolated from ground, whereby the circuit including the connection may be used for powering or communicating with the electrical device. The ground may correspond to a cylinder head of an engine in which the valvetrain is installed. Forming the connection through abutting surfaces that are free to undergo relative motion may reduce or eliminate the need to run wires between parts that undergo relative motion.

[0008] In some of these teachings, one of the two distinct parts is mounted to the rocker arm assembly and the other is not. In some others of these teachings, both of the two distinct parts are mounted to the rocker arm assembly. One of the two distinct parts that form the electrical connection may be mounted to the rocker arm on which the electrical device is mounted. In some of these teachings, the electrical connection part mounted to the rocker arm is held proximate a spring post of the rocker arm.

[0009] In some of these teachings, one of the two distinct parts that forms the electrical connection is mounted to a rocker arm and the other is mounted to a pivot providing a fulcrum for that rocker arm. In some of these teachings, the pivot is a lash adjuster, such as a hydraulic lash adjuster. Mounting the one part to the rocker arm and the other to the pivot may facilitate positioning the two parts forming the electrical connection relative to one another. The part mounted to the pivot may be connected to an engine electrical system through wires that undergo relatively little motion.

[0010] In some of these teachings, the electrical circuit includes a load-bearing member of the rocker arm assembly. In some of these teachings, all or part of a load-bearing member of the rocker arm assembly forms a part of the electrical circuit that is electrically isolated from ground. In some of these teachings, the load-bearing member is a pivot. In some of these teachings, the electrical connection is formed across a load-bearing surface.

[0011] In some of these teachings, the electrical device is powered through the electrical circuit. In some of these teachings, the electrical device communicates with a processor through the electrical circuit. In some of these teachings, the electrical device is an

electromechanical latch assembly. In some of these teachings, the electrical device is a sensor.

[0012] In some of these teachings, one of the two distinct parts forming the electrical connection is mounted to the rocker arm bearing the electrical device and the rocker arm is operative to pivot in response to actuation of the cam follower by a camshaft-mounted cam. The pivoting is operative to cause one of the two distinct parts to move relative to the other. Pivoting may take place on a fulcrum provided by a lash adjuster or the like. In some of these teachings, at least one of the two part surfaces forming the electrical connection is relatively flat and has a surface normal vector that is substantially parallel to the axis of pivoting. In some of these teachings, the surface normal vector is nearly perpendicular to a direction in which the lash adjuster extends to adjust the lash. In some others of these teachings, one of the two part surfaces has a surface normal vector that points approximately directly toward or away from the axis about which the pivoting occurs. In some of these others teachings, one of the two part surfaces has a radius of curvature that is approximately equal to the surface's distance from the axis about which the pivoting occurs. Structures satisfying the foregoing criteria may facilitate maintaining contact between the two distinct parts forming the electrical connection even as the parts undergo relative motion due to pivoting of the rocker arm. Some of these structures facilitate maintaining contact between the two distinct parts even as one of the parts is moved relative to the other as a result of lash adjustment.

[0013] In some aspects of these teachings, one of the two part surfaces forming the electrical connection is a projecting conductive member. The projecting conductive member may be rigid. For example, the projecting conductive member may be a metal pin projecting outward from a rocker arm. In some of these teachings, the projecting conductive member projects outward from a rocker arm parallel or nearly parallel to an axis on which the rocker arm pivots. In some of these teachings, the projecting conductive member is mounted to the rocker arm and is located proximate an axis on which the rocker arm pivots.

[0014] The surfaces forming the electrical connection may be exposed to the environment of the rocker arm assembly and may become coated with a thin layer of engine oil. In some of these teachings, the rocker arm assembly is operative to cause the surface of one of the two distinct parts to slide over the other. In some of these teachings, one of the parts is a brush. Bushes may have the effect of pushing oil from between the abutting surfaces of the two distinct parts. In some of these teachings, one of the two distinct parts is configured to roll over the other. Rolling contact may have the advantage of reduced wear.

[0015] According to some aspects of the present teachings, the internal combustion engine includes a spring biasing one of the two distinct parts whose abutting surfaces form the electrical connection against the other. In some of these teachings the spring itself forms part of the electrical circuit. The spring may facilitate good contact and compensate for wear. In some of these teachings, one of the parts is a pogo pin connector.

[0016] According to some aspects of the present teachings, the electrical connection is made within an interface between load-bearing members of the valvetrain. In some of these teachings, one of the two part forming the electrical connection includes an insulating structure surrounding the surface through which the electrical connection is made. In some of these teachings the connection is made within an area of contact between a lash adjuster and a rocker arm. Forming the connection within a load-bearing interface keeps the connection within a volume already occupied by the rocker arm assembly. [0017] According to some aspects of the present teachings, one of the two distinct parts forming the electrical connection is a conductor integrated into the structure of a load-bearing member of the valvetrain. In some of these teachings, the conductor is a conductive trace formed on a surface of the load-bearing member. In some of these teachings, the load-bearing member is a valve stem.

[0018] In some of these teachings, the electrical device is an electromechanical latch assembly having a latch pin translatable between a first position and a second position. One of the first and second latch pin positions provides a configuration in which the rocker arm assembly is operative to actuate a moveable valve in response to actuation of the cam follower by a camshaft-mounted cam to produce a first valve lift profile. The other of the first and second latch pin positions provides a configuration in which the rocker arm assembly is operative to actuate the moveable valve in response to actuation of the cam follower by the camshaft- mounted cam to produce a second valve lift profile, which is distinct from the first valve lift profile, or the moveable valve is deactivated. This structure may provide cylinder deactivation (CDA) or variable valve lift (VVL).

[0019] In some of these teachings, the electromagnetic latch assembly include a coil operable to actuate the latch pin between the first and the second positions. In some of these teachings the electromagnetic latch assembly provides the latch pin with positional stability independently from the solenoid when the latch pin is in the first position and when the latch pin is in the second position. In some of these teachings,

the electromagnetic latch assembly is operable with a DC current in a first direction to actuate the latch pin from the first position to the second positions and with a DC current in a second direction, which is a reverse of the first, to actuate the latch pin from the second position to the first position. Having the electromagnetic latch assembly make the latch pin stable without power in both the first and the second positions allows the electrical connection to be broken without the latch pin position changing.

[0020] According to some aspects of the present teachings, the rocker arm assembly is operative to cyclically break the electrical connection in relation to actuation of the cam follower. In some of these teachings, an internal combustion engine includes circuitry operative to determine the status of the electrical connection. The status of the electrical connection provides information that may be used to provide diagnostic feedback or to guide an engine control. In some of these teachings, one of the two distinct parts is operative to form a second electrical connection over a period when it is not forming the first electrical connection. In some of these teachings, the engine includes circuitry operative to determine the status of the second electrical connection. Determinations of the statuses of the first and second electrical connections may provide information that can be used to perform an engine management or diagnostic operation. In some of these teachings, one of these structures is used to perform an on board diagnostic, which may result in a diagnostic report. In some of these teachings, one of these structures is used to provide information relating to whether the rocker arm is lifted at one or more particular times and an engine management operation is performed on the basis of that information.

[0021] Additional aspects of the invention relate to methods of powering or communicating with an electrical device mounted to a rocker arm assembly. The method includes powering or communicating with the electrical device through an electrical circuit that includes an electrical connection formed by abutment between the surfaces of two distinct parts and operating the rocker arm assembly in such a way that the surfaces move relative to one another. In some of these teachings, the electrical connection is preserved throughout operation of the rocker arm assembly. In some of these teachings, the electrical connection is episodically broken.

[0022] According to some aspects of the present teachings, an electrical device mounted to a rocker arm is connected through a circuit that includes a wire that runs through a pivot providing a fulcrum for the rocker arm. In some of these teachings, the wire enters the pivot through a port designed to admit hydraulic fluid into the pivot. In some of these teachings, the wire runs upward through a passage within the lash adjuster. In some of these teachings, the wire exits the lash adjuster at a port suitable for providing hydraulic fluid from the hydraulic lash adjuster to a rocker arm that pivots on the hydraulic lash adjuster. In some of these teachings, the wire further passes through a passage in the rocker arm. In some of these teachings, the wire enters a chamber in the rocker arm designed as a hydraulic chamber. In this way, a hydraulic lash adjuster and or a rocker arm designed for hydraulic latching may be adapted to electrical latching with minimum modification. Moreover, the hydraulic lash adjuster and or the rocker arm may provide protective conduits for the wires. These locations may also be ones where the wires undergo relatively little movement in comparison to wires running to other parts of the rocker arm assembly.

[0023] The primary purpose of this summary has been to present certain of the inventors' concepts in a simplified form to facilitate understanding of the more detailed description that follows. This summary is not a comprehensive description of every one of the inventors' concepts or every combination of the inventors' concepts that can be considered "invention". Other concepts of the inventors will be conveyed to one of ordinary skill in the art by the following detailed description together with the drawings. The specifics disclosed herein may be generalized, narrowed, and combined in various ways with the ultimate statement of what the inventors claim as their invention being reserved for the claims that follow. Brief Description of the Drawings

[0024] Fig. 1 is a perspective view of a portion of an internal combustion engine including a valvetrain according to some aspects of the present teachings.

[0025] Fig. 2 is a cross-sectional view of a portion of the internal combustion engine of Fig. 1 with a cam on base circle.

[0026] Fig. 3 is a cross-sectional view of the internal combustion engine of Fig. 1 with a rocker arm assembly in a latched stated and a cam off base circle.

[0027] Fig. 4 is a cross-sectional view of a portion of the internal combustion engine of Fig.

1 with a rocker arm assembly in an unlatched stated with a cam off base circle.

[0028] Fig. 5 is a perspective view of a rocker arm assembly of the internal combustion engine of Fig. 1 with electrical connections according to some aspects of the present teachings.

[0029] Fig. 6 is a cross-section along line 6-6 of Fig. 5 showing an electrical connection according to some aspects of the present teachings.

[0030] Fig. 7 is an exploded view of the parts shown in Fig. 5.

[0031] Fig. 8 is a schematic diagram of a circuit according to some aspects of the present teachings that may provide power to a rocker arm-mounted electrical device in the internal combustion engine of Fig. 1.

[0032] Fig. 9 is a cross-sectional view of a portion of an internal combustion engine including a valvetrain according to some aspects of the present teachings.

[0033] Fig. 10 is a cross-sectional view of a portion of the internal combustion engine of Fig.

9 with a rocker arm assembly in a latched stated and a cam off base circle.

[0034] Fig. 1 1 is a schematic diagram of a circuit according to some aspects of the present teachings that may provide power to a rocker arm-mounted electrical device in the internal combustion engine of Figs. 9 and 10.

[0035] Fig. 12 is a schematic diagram of a circuit according to some aspects of the present teachings that may provide diagnostic information for a rocker arm assembly of the internal combustion engine of Figs. 9 and 10.

[0036] Fig. 13 is a cross-sectional view of a portion of an internal combustion engine including a valvetrain according to some aspects of the present teachings.

[0037] Fig. 14 is a schematic diagram of a circuit according to some aspects of the present teachings that may provide power to a rocker arm-mounted electrical device in the internal combustion engine of Fig. 13.

[0038] Fig. 15 is a perspective view of a rocker arm assembly of the internal combustion engine of Figs. 16 and 17.

[0039] Fig. 16 is a cross-sectional view of a portion of an internal combustion engine including a valvetrain according to some aspects of the present teachings. [0040] Fig. 17 is a cross-sectional view of a portion of the internal combustion engine of Fig. 16 with a rocker arm assembly in a latched stated and a cam off base circle.

[0041] Fig. 18 is a schematic diagram of a circuit according to some aspects of the present teachings that may provide power to a rocker arm-mounted electrical device in the internal combustion engine of Figs. 16 and 17.

[0042] Fig. 19 is a cross-sectional view of a portion of an internal combustion engine including a valvetrain according to some aspects of the present teachings.

[0043] Fig. 20 is a schematic diagram of a circuit according to some aspects of the present teachings that may provide power to a rocker arm-mounted electrical device in the internal combustion engine of Fig. 19.

[0044] Fig. 21 is a schematic diagram of a circuit according to some aspects of the present teachings providing communication with a rocker arm-mounted sensor mounted.

[0045] Fig. 22 is a rear view of a rocker arm assembly in a valvetrain according to some aspects of the present teachings.

[0046] Fig. 23 is a side view of the rocker arm assembly of Fig. 22.

[0047] Fig. 24 is a cross-sectional view of a portion of an internal combustion engine including a valvetrain according to some aspects of the present teachings.

[0048] Fig. 25 is a cross-sectional view of a portion of an internal combustion engine including a valvetrain according to some aspects of the present teachings.

[0049] Fig. 26 is a schematic diagram of a circuit according to some aspects of the present teachings that may provide power to a rocker arm-mounted electrical device in the internal combustion engine of Fig. 25.

[0050] Fig. 27 is a cross-sectional view of a portion of an internal combustion engine including a valvetrain according to some aspects of the present teachings.

[0051] Fig. 28 is a cross-sectional view of a portion of an internal combustion engine including a valvetrain according to some aspects of the present teachings.

Detailed Description

[0052] In the drawings, some reference characters consist of a number followed by a letter. In this description and the claims that follow, a reference character consisting of that same number without a letter is equivalent to a listing of all reference characters used in the drawings and consisting of that same number followed by a letter. For example, "permanent magnet 200" is the same as "permanent magnet 200A, 200B". Permanent magnet 200 is there for a generic reference that includes the specific instances permanent magnet 200A and permanent magnet 200B. Where options are provided for one instance subject to a generic reference, those options are to be given consideration in connection with all instances subject to that generic reference. [0053] Figs. 1-7 illustrate aspects an internal combustion engine 100A that includes a cylinder head 102 and valvetrain 104A in accordance with some of the present teachings.

Referring to Fig. 1 , internal combustion engine 100A may include a camshaft supporting member 1 17 and a camshaft 109 on which are mounted eccentrically shaped cams 107.

Camshaft supporting member 117 may be a cam tower. In some of these teachings, camshaft supporting member 1 17 is a cam carrier. Valvetrain 104A may include a plurality of rocker arm assemblies 106A. A mounting frame 132A may mount to camshaft supporting member 117 and hold pogo pins 110A adjacent and in abutment with contact pads 175A on rocker arm assemblies 106A. Mounting frame 132A may include two members that are fixed together: a first member 134 that mounts to camshaft supporting member 1 17 and a second member 133 that holds pogo pins 11 OA. Second member 134 may be made of plastic or another non- conductive material. A connection plug 174 may provide a convenient way to couple wires 173 from pogo pin connectors 1 10A to an electrical system of internal combustion engine 100A. Wires 173 and or connection plug 174 may also be attached to mounting frame 132A.

[0054] With reference to Figs. 2-4, internal combustion engine 100A may include a movable valve 152, such as a poppet valve, which has a seat 156 within a combustion chamber 112 formed by cylinder head 102. Rocker arm assembly 106A may include inner arm 103B, outer arm 103A, and a pivot 140, which may be a hydraulic lash adjuster. Hydraulic lash adjuster (HLA) 140 may include an inner sleeve 145 and an outer sleeve 143. A cam follower 11 1 may be mounted to inner arm 103B and be configured to engage a cam 107 as camshaft 109 rotates. Rocker arm assembly 106A is operative to transmit force from cam 107 to actuate valve 152. An electromechanical latch assembly 122 may be mounted to outer arm 103A. Outer arm 103A is mobile relative to cylinder head 102.

[0055] Electromechanical latch assembly 122 includes a coil 1 19. Coil 119 may be rigidly mounted with respect to outer arm 103A. Electromechanical latch assembly 122 may include permanent magnets 120A and 120B, a latch pin 1 15, and a shell 1 16. Shell 116 may be made of a low coercivity ferromagnetic material such as soft iron. Permanent magnets 120A and 120B may be annular and arranged with confronting polarities and with a ring 121 of low coercivity ferromagnetic material between them. Latch pin 115 may include a latch head 1 18 and a low coercivity ferromagnetic portion 123. Low coercivity ferromagnetic portion 123 may be a sleeve on an otherwise paramagnetic latch pin 1 15. Latch pin 1 15 may be translatable between extended and retracted positions.

[0056] Figs. 2 and 3 show latch pin 115 in the extended position. The extended position for latch pin 1 15 may be described as an engaging position and provides an engaging configuration for rocker arm assembly 106A. If cam 107 is rotated while latch pin 1 15 is in the engaging position, head 1 18 of latch pin 1 15 may engage lip 113 of inner arm 103B. The force of cam 107 on cam follower 1 11 may actuate cam follower 11 1 causing both inner arm 103B and outer arm 103A to pivot together on hydraulic lash adjuster 140, bearing down on valve 152 and compressing valve spring 153. Valve 152 may be lifted off its seat 156 as shown in Fig. 3 with a valve lift profile determined by the shape of cam 107. The valve lift profile is the shape of a plot showing the height by which valve 152 is lifted of its seat 156 as a function of angular position of camshaft 109. In the engaging configuration, camshaft 109 may do work on rocker arm assembly 106 as cam 107 rises off base circle. Much of the resulting energy may be taken up by valve spring 153 and returned to camshaft 109 as cam 107 descends back toward base circle.

[0057] If cam 107 is rotated while latch pin 1 15 is in the non-engaging position as shown in Fig. 4, the downward force on cam follower 11 1 may be distributed between valve 152 and torsion springs 159. Torsions springs 159 may be tuned relative to valve spring 153 such that torsion springs 159 yield in the non-engaging configuration while valve spring 153 does not. Inner arm 103B may descend as torsion springs 159 wind and outer arm 103A may remain in place. As a result, valve 152 may remain on its seat 156 even as cam 107 rotates. In the non- engaging configuration, camshaft 109 still does work on rocker arm assembly 106 as cam 107 rises off base circle. But in this case, most of the resulting energy is taken up by torsions springs 159, which act as lost motion springs.

[0058] Hydraulic lash adjuster 140 may be replaced by another type of lash adjuster or by a static pivot. Lash adjustment may be implemented using a hydraulic chamber 144 that is configured to vary in volume as hydraulic lash adjuster 140 extends or contracts through relative motion of inner sleeve 145 and outer sleeve 143. A supply port 146 in outer sleeve 143 may allow a reservoir chamber 142 to be filled from an oil gallery 128 in cylinder head 102. The fluid may be engine oil, which may be supplied at a pressure of about 2 atm. When cam 107 is on base circle, this pressure may be sufficient to open check valve 141 , which admits oil into hydraulic chamber 144. The oil may fill hydraulic chamber 144, extending hydraulic lash adjuster 140 until there is no lash between cam 107 and roller follower 111. As cam 107 rises off base circle, hydraulic lash adjuster 140 may be compressed, pressure in hydraulic chamber 144 may rise, and check valve 141 may consequently close.

[0059] Shell 1 16 may be formed by a plurality of pieces of low coercivity ferromagnetic material, which may be described as pole pieces in that they are operative within

electromechanical latch assembly 122 to guide magnetic flux from the poles of permanent magnets 120 or coil 119. Rocker arm 103A may be formed of low coercivity ferromagnetic material and that may perform all part of this same function. Shell 116 may wrap around the outside coil 1 19 and may also wrap partially inside to provide stepped edges 129. Low coercivity ferromagnetic portion 123 of latch pin 115 may be shaped to mate with stepped edges 129. During actuation, magnetic flux from coil 1 19 may follow a circuit that crosses an air gap between a stepped edge 129 and latch pin 115, in which case the stepped edge 129 may be operative to increase the magnetic forces through which latch pin 1 15 is actuated.

[0060] Electromechanical latch assembly 122 may provide both extended and retracted positions in which latch pin 115 is stable. As a consequence, either the latched or unlatched configuration can be reliably maintained without coil 119 being powered. This may be advantageous when an electrical connection 108 is subject to interruption. Positional stability refers to the tendency of latch pin 1 15 to remain in and return to a particular position. Stability is provided by restorative forces that act against small perturbations of latch pin 1 15 from a stable position. Stabilizing forces may be provided by permanent magnets 120. Each of the extended and retracted positions may provide low reluctance pathways for magnetic flux from each of the permanent magnets 120. The reluctance of these pathways may be increased by small perturbations of latch pin 1 15 from a stable position. Alternatively, or in addition, one or more springs may be positioned to provide positional stability.

[0061] A conventional solenoid switch forms a magnetic circuit that includes an air gap, a spring that tends to enlarge the air gap, and an armature moveable to reduce the air gap.

Moving the armature to reduce the air gap reduces the magnetic reluctance of that circuit. As a consequence, energizing a conventional solenoid switch causes the armature to move in the direction that reduces the air gap regardless of the direction of the current through the solenoid or the polarity of the resulting magnetic field. With electromechanical latch assembly 122, however, latch pin 115 may be moved in either one direction or another depending on the polarity of the magnetic field generated by coil 1 19.

[0062] If coil 119 is energized with a direct current (DC) in a first direction, it may induce latch pin 115 to actuate from the extended position to the retracted position. The magnetic flux from coil 1 19 may reverse the magnetic polarity in low coercivity ferromagnetic elements such as shell 1 16, ring 121 , and sleeve 123 that form low reluctance magnetic pathways through which permanent magnets 120 stabilize latch pin 1 15 in the extended position. That may greatly increase the reluctance of those magnetic circuits and cause magnetic flux from permanent magnets 120 to shift. The net magnetic forces on latch pin 1 15 may drive it to the retracted position.

[0063] While permanent magnets 120 may initially hold latch pin 1 15 in the extended position, at some point during latch pin 115's progress toward the retracted position, permanent magnets 120 begins to attract latch pin 115 toward the retracted position. At this point, the pathways for magnetic flux from permanent magnets 120 have shifted. Beyond this point, coil 119 may be disconnected from its power source and latch pin 1 15 may still complete its travel to the retracted position.

[0064] If coil 119 is energized with a current in a second direction, which is the reverse of the first direction, it may induce latch pin 1 15 to actuate from the retracted position to the extended position. The magnetic flux from coil 119 may reverse the magnetic polarity in low coercivity ferromagnetic elements forming magnetic circuits through which permanent magnets 120 stabilized latch pin 115 in the retracted position. That may greatly increase the reluctance of those magnetic circuits and cause magnetic flux from permanent magnets 120 to shift again. The net magnetic forces on latch pin 1 15 may drive it to the extended position. At some point during latch pin 1 15's progress toward the extended position, permanent magnets 120 begin to attract latch pin 1 15 toward the extended position. Accordingly, at some point during latch pin 115's progress, coil 119 may be disconnected from its power source and latch pin 115 may still complete its travel to the extended position.

[0065] As used herein, a permanent magnet is a high coercivity ferromagnetic material with residual magnetism. A high coercivity means that the polarity of permanent magnets 120 remains unchanged through hundreds of operations through which electromechanical latch assembly 122 is operated to switch latch pin 1 15 between the extended and retracted positions. Examples of high coercivity ferromagnetic materials include compositions of AINiCo and NdFeB.

[0066] Coil 1 19 may be powered through an electrical circuit 105A that includes one or more electrical connections 108A formed by contact between pogo pins 11 OA and contact pads 175A. Fig. 8 provides a schematic diagram for an example electrical circuit 105A that also includes an H-bridge 177. H-bridge 177 may include diodes 190 and switches 191 that can be operated through signals 192 to selectively apply voltage from a power source 176 to coil 119 with current flowing in either a first or a second direction. One polarity may be used when it is desired to actuate latch pin 115 to the extended position and the other polarity may be used when it is desired to actuate latch pin 1 15 to the retracted position. The potential of ground 172 may be the potential of cylinder head 102. An alternative circuit 105A could be made operative to selectively couple coil 1 19 with one of two power sources, one source having a potential above ground 172 and the other below ground 172. In this alternative circuit structure, a single electrical connection 108A may be used to provide coil 119 with power for current in either direction while a connection to ground 172 may be formed through the structure of rocker arm assembly 106A.

[0067] In some alternative embodiments, electromechanical latch assembly 122 includes two coil 1 19 isolated from one-another, one with coils wound in a first direction and the other with coils wound in the opposite direction. Two circuits 105A with electrical connections 108 may then be used to power electromechanical latch assembly 122. One of the circuits 105A may be closed to actuate latch pin 1 15 in a first direction and the other to actuate latch pin 115 in the reverse direction.

[0068] The portion of circuit 105A that includes electrical connection 108A is electrically isolated from ground 172 and cylinder head 102. Electrical connection 108A may be made by surface contact between pogo pin 1 10A and contact pad 175A. Contact pad 175A may be mounted to but insulated from rocker arm 103A. Contact pad 175A may at times move in response to rotation of cam 107 by virtue of contact pad 175A being mounted to outer arm 103A. Accordingly, rocker arm assembly 106A is operative to cause the abutting surfaces of pogo pin connector 1 10A and contact pad 175A that form electrical connection 108A to shift and move relative to one another as cam 107 rotates. Different types of abutting structures could replace contact pad 175A and pogo pin connector 1 10A.

[0069] With reference to Fig. 6, pogo pin connector 110A may include a spring 178, an extending member 179, and a housing member 180. Spring 178 may be configured to bias extending member 179 outward from housing member 180 with the effect of providing a force that tends to lengthen pogo pin connector 11 OA and maintain extending member 179 in contact with an opposing surface such as a surface of contact pad 175A. Extending member 179 is conductive. Housing member 180 may be conductive. Spring 178 may also be conductive. Accordingly, current through extending member 179 may flow though spring 178, housing member 180, or both.

[0070] Rocker arm 103A is operative to pivot on HLA 140, which provide a fulcrum. The motion of rocker arm 103A is substantially constrained to movement in a plane parallel to an axis on which rocker arm 103A pivots. Contact pad 175A may provide a relatively flat surface having a surface normal vector that is substantially parallel to that pivot axis. That geometry allows pogo pin connector 1 10A to remain substantially stationary while sliding over and continuously abutting contact pad 175A even as rocker arm 103A undergoes the pivoting movement. Pogo pin connector 1 10A may be fit with a roller and roll over contact pad 175A as rocker arm 103A pivots.

[0071] Contact pad 175A may be mounted proximate or directly to a spring post of rocker arm 103A. A spring post is a part of rocker arm 103A around which torsion spring 159 winds. With reference to Fig. 5, torsion springs 159 are mounted on hubs 149, which fit over the spring posts 157 (shown in the example of Fig. 23, but not in the example Fig 5). Mounting frame 132A may hold pogo pin connector 11 OA in a substantially fixed position relative to cylinder head 102. Pogo pin connector 11 OA could be otherwise held in a substantially fixed position relative to cylinder head 102. Alternatively, pogo pin connector 1 10A could be mounted to outer arm 103A and contact pad 175A could be mounted to mounting frame 132A.

[0072] Figs. 22-23 illustrate an internal combustion engine 100K including a rocker arm assembly 106K that like the rocker arm assembly 106A of engine 100A has an electrical connection 108 formed by abutment between a part 1 10 mounted to a rocker arm 103 and a part 175 mounted off that rocker arm 103. In both of these example, the part 1 10 mounted to the rocker arm 103 may be mounted to a spring post 157 of the rocker arm 103. [0073] In engine 1 10K, an electrical connection 108K may be formed between contact pin 175K mounted to rocker arm 103A and motor brushes 110K mounted off rocker arm 103A. Motor brushes 1 10K may be held by a mounting frame 132K in a position where they are biased against and slide over contact pin 175K. Frame 132K is itself mounted to HLA 140. Frame 132K may extend to encompass a plurality of HLAs 140, which may facilitate holding mounting frame 132K in a fixed position. A wiring harness 168 may be mounted to frame 132K. Wiring harness 168 may include a plurality of wires 173 that connect to motor brushes 1 1 OK, whereby wiring harness 11 OK may carry power or communication signals for coil 119 or other electrical devices on a plurality of rocker arm assemblies 106K.

[0074] With reference to Figs. 22 and 23, mounting a part 175 to a spring post 157 may place that part proximate a pivot axis 169 of rocker arm 103A. As a consequence of that proximity, the parts 110K and 175K that form electrical connection 108K undergo relatively little relative motion as rocker arm 103A moves through its range of motion. That may facilitate maintaining electrical connection 108K continuously.

[0075] While the top of HLA 140 may be approximately hemispherical or cylindrical and the mating surface of rocker arm 103A may have an approximately corresponding shape, either of these surfaces may deviate to some degree from any such idealized shape or perfect correspondence. As a result, the movement of rocker arm 103A may not be precisely restricted to a simple pivoting motion and the location of pivot axis 169 may not be exactly and uniquely determined. These types of variations from the ideal that are common in rocker arm assemblies and the resulting uncertainties in location of pivot axis 169 are negligible for purposes of the present disclosure.

[0076] Figs. 9-10 illustrate an internal combustion engine 100B that includes a valvetrain 104B having a rocker arm assembly 106B. Coil 1 19 of rocker arm assembly 106B may be powered through an electrical circuit 105B for which Fig. 11 provides an example. Electrical circuit 105B may include an electrical connection 108B formed between brushes 110B and contact pad 175B. Contact pad 175B may be mounted to rocker arm 103A.

[0077] Electrical circuit 105B may include power sources 176A and 176B. One of these sources may provide a voltage above the potential of cylinder head 102 while the other provides a voltage below the potential of cylinder head 102. Cylinder head 102 may be operative as a ground. Switches 191A and 191 B may be operated through control signals 192A and 192B to selectively couple one or the other of sources 176A and 176B to a first pole of coil 119. Wire 196 may connect a second pole of coil 119 to rocker arm 103A, which may be electrically coupled to cylinder head 102 through the structure of rocker arm assembly 106B including outer arm 103A and HLA 140. Alternatively, rocker arm assembly 106B may be provided with two electrical connections 108B and coil 119 may be powered through a circuit like electrical circuit 105A. [0078] Valvetrain 104B may be operative to move rocker arm 103A through a range of motion. The range of motion may include a first portion over which connection 108B is closed and a second portion over which electrical connection 108B is open. Within at least the portion of the range of motion over which connection 108B is closed, the motion of rocker arm 103B may move contact pads 175B in a direction that is substantially perpendicular to the orientation of brushes 110B. Brushes 110B may therefore bend and slide over the surfaces of contact pads 175B. Brushes 1 10B may be of a type used in motors.

[0079] Surfaces adjacent the conducting surface of contact pad 175B may be insulated so that electrical circuit 105B is opened and closed as electrical connection 108B is opened and closed. Electrical circuit 105B may be monitored to detect the forming and breaking of electrical connection 108B. This information may be used to monitor the motion of rocker arm 103A. That information may be useful in making diagnostic determinations, which may be reported. Alternatively, that information may be used for engine management.

[0080] A current measuring device 193 may be provided to detect the forming and breaking of electrical connection 108B. As illustrated in Fig. 1 1 , current measuring device 193 may include a shunt resistor 194 configured within electrical circuit 105B and a voltage measuring device 195 connected across shunt resistor 194. Another alternative for current measuring device 193 is an inductive coil configured to measure current in circuit 105B.

[0081] In some aspects of the present teachings, a second contact pad 175C is also mounted to rocker arm 103A. As shown in Fig. 10, over a portion of rocker arm 103A's range of motion, brushes 1 10B may make contact with contact pad 175C to form an electrical connection 108C, completing a circuit 105C for which Fig. 12 provides an example. The portion of rocker arm 103A's range of motion over which brushes 110B make contact with second contact pad 175C to form electrical connection 108C may be disjoint from that portion over which brushes 110B make contact with contact pad 175B to form electrical connection 108B. A resistor 182 may be positioned to connect between second contact pad 175C and a ground, such as cylinder head 102. Resistor 182 may be selected to be the principal source of resistance in circuit 105C.

[0082] A voltage may be applied to circuit 105C at a time when actuation of latch pin 1 15 is not desired. The voltage may be from source 176A, source 176B, or some other source. In some of these teaching, that voltage is selected to be of the wrong polarity to induce motion of latch pin 1 15 from its current position. In some of these teaching, that voltage is less than a voltage required to actuate latch pin 115. Given the resistance of circuit 105C and the magnitude of the applied voltage, a current of predictable magnitude may flow through circuit 105C but only at such times that electrical connection 108C is closed. The presence or absence of that current may be detected by current measuring device 193 and that detection used to monitor the motion of rocker arm 103A and make diagnostic determinations on the basis thereof.

[0083] Contact pads 175B and 175C are mounted to rocker arm 103A on a projecting structure 151. Projecting structure 151 supports contacts pads 175B and 175C on a surface 150 that has a normal vector 136 that points approximately directly away from the approximate axis 169 about which rocker arm 103A pivots. "Points approximately directly away" means that a line through normal vector 136 would come close to intersecting axis 169. The radius of curvature of surface 150 is approximately equal to its distance from pivot axis 169. As a result of these two conditions, the distance from the base of motor brushes 110B and surface 150 remains nearly constant as rocker arm 103A pivots through it range of motion. This structure facilitates motor brushes 110B making contact first with contact pad 175B and then with contact pad 175C as rocker arm 103A pivots through it range of motion. If contact pad 175B were extended along surface 150, this same structure could be used to maintain contact between motor brushes 1 10B and contact pad 175B throughout the range of motion of rocker arm 103A.

[0084] Fig. 24 illustrates an internal combustion 100J that uses a similar structure to maintain a connection 108J between a roller 175J mounted to rocker arm assembly 106J and a contact pad 1 10J. Contact pad 110J may be held by frame 211 to a cam carrier 1 17. Contact pad 1 10J has a surface with a radius of curvature approximately equal to its distance from pivot axis 169 and a surface normal vector 136B oriented approximately in the direction of pivot axis 169. This direction need not be the shortest distance to pivot axis 169, but may approximately intersect pivot axis 169 with some angle of incidence. This structure allows roller 175J to remain in abutment with contact pad 110J even as rocker arm 103A moves through its range of motion. Roller 175J may be biased against contact pad 1 10J by a spring (not shown) to maintain contact while allowing some upward and downward motion of rocker arm 103A for lash adjustment.

[0085] Fig. 13 illustrates an internal combustion engine 100D that includes a valvetrain 104D having a rocker arm assembly 106D. Rocker arm assembly 106D includes a rocker arm 103A on which may be mounted an electromechanical latch assembly 122 that includes coil 119. Coil 1 19 may be powered through an electrical connection 108D that may be formed within an interface region 154 where rocker arm 103A contacts and pivots on H LA 140. A pair of electrical connections 108D may be provided side-by-side at this location to form an electrical circuit 105D as illustrated in Fig. 14. Rocker arm 103A and H LA 140 are (mechanical) load- bearing members of rocker arm assembly 106D. Other examples of load-bearing members of rocker arm assembly 106D include elephant's foot 101 , roller follower 1 11 , roller bearings 1 14 and their bearing races, latch pin 115, poppet valve 152, axle 155, and torsion springs 159.

[0086] Electrical connections 108D may be formed by surface contact between first parts 110D mounted to H LA 140 and second parts 175D mounted to rocker arm 103A. Parts 1 10D may be insulated from surrounding areas of HLA 140. An insulating layer 171 may insulate part 175D from surrounding areas of rocker arm 103A. One or both of parts 110D and 175D may be sprung to bias them into contact. In one example, parts 175D are spring clips. In another example, parts 110D are pogo pin connectors. Both parts 175D and 1 10D may include sprung members biasing them into contact. Insulating layer 171 may be formed from any suitable material.

[0087] Engine 100D has wires 173 that form part of electrical circuit 105D entering HLA 140 through a port 183 and running upward to rocker arm 103A through a passage 184 within HLA 140. Wires 197, which form another part of circuit 105D, run through a hydraulic passage 189 in rocker arm 103A. Port 183 may be a port designed to admit hydraulic fluid from cylinder head 102 into HLA 140. The chamber within rocker arm 103A that houses electromechanical latch assembly 122 may have been designed as a hydraulic chamber for a hydraulic latch. The interface 154 between HLA 140 and rocker arm 103A may have been designed to form a seal and allow the transfer of hydraulic fluid from passage 184 to passage 189. Running wires in these locations can be useful even if sliding electrical connection 108D is replaced by a fixed connection or a continuous run of wire.

[0088] Engine 100D is an example in which an electrical connection 108 is formed by abutment between a first part 1 10 mounted to or forming part of a hydraulic lash adjuster 140 and another part 175 mounted to of forming part of a rocker arm 103. Engine 100G of Fig. 25 provides another example. Engine 100G is also an example in which a rocker arm assembly 106G includes a hydraulic lash adjuster 140G that may be electrically isolated from cylinder head 102 and form part of a circuit 105L through which an electrical device, such as solenoid 122, mounted to a rocker arm 103A may be powered. Fig. 26 provides a diagram for an example circuit 105L.

[0089] Hydraulic lash adjuster 140G may be insulated from cylinder heard 102 by an insulating sleeve 201. Alternatively, a non-conductive coating may be used in place of sleeve 201. Hydraulic lash adjuster 140G may be insulated from rocker arm 103A by insulating cup 199. Insulating cup 199 may be load-bearing and constructed of any suitable material. A suitable material may be, for example, a ceramic such as SiC or a polymer such as an epoxy. Insulating cup 199 may be replaced by a similar structure formed into HLA 140G. An electrically insulating coating may be used in place of either of these structures.

[0090] Inner sleeve 145 and or outer sleeve 143 of HLA 140G may be left free to rotate within the bore 138 in cylinder head 102 to reduce wear at the interface with rocker arm 103A. On the other hand, it may be desirable to restrict rotation of insulating sleeve 201 so that it may provide a stationary support for a wire 173. A conductive ring 203 may be used to form an electrical connection between wire 173 and outer sleeve 143 while permitting relative rotation between outer sleeve 143 and insulating sleeve 201. Besides electrical connection 108L, circuit 105L includes sliding contact between conductive ring 203 and outer sleeve 143 and sliding contact between outer sleeve 143 and inner sleeve 145

[0091] A leaf spring 175L formed of one or more ribbons of metal may be mounted to outer arm 103A and form electrical connection 108L by sliding contact with inner sleeve 145, also referred to as part 1 10L in this example. Brushes or another type of structure could be used in place of leaf spring 175L to make contact between the portion of circuit 105L that is mounted to rocker arm 103A and the portion of circuit 105L that is mounted to or part of HLA 140G. In some of these teachings, the contact is made with the top of inner sleeve 145. Such a contact could be placed underneath the insulating cup 199. Alternatively, rocker arm 103A could be electrically isolated from cylinder head 102 and electrical connection 108L could be made by direct contact between HLA 140G and rocker arm 103A. Another connection 108 formed by abutment could be used for a ground connection.

[0092] Mounting wires 173 to HLA 140 may provide several advantages. One advantage is that HLA 140 may provide a relatively stationary location to mount wires, particularly an HLA 140G fit with a sleeve 201 that is prevented from rotating. Another advantage is that HLA 140 provides a location to mount a part 110 in which it has a well-controlled spatial relationship to another part 175 that may be mounted to a rocker arm 103. The parts 1 10 and 175 may then be configured to abut and form electrical connection 108. Engine 100M of Fig. 27 and engine 100N of Fig. 28 provide additional examples demonstrating this concept.

[0093] With reference to Fig. 27, an electrical connection 108M is formed by abutment between part 110M mounted to HLA 140G and part 175M mounted to rocker arm 103A. Part 110M is a spring, brush or other structure with sufficient resilience to bend when deformed by movement of rocker arm 103A but spring back to maintain contact with part 175M when the movement is reversed.

[0094] With reference to Fig. 28, a spring, brush or other structure 175N that is mounted to rocker arm 103A is biased against a conductive ring 1 10N mounted to the outside of insulating sleeve 201 in order to form the connection 110N. A rod 209 or other structure may extend from rocker arm 103A to support structure 175N in proximity to HLA 140G. Structure 175N may have sufficient resilience to maintain electrical connection 11 ON throughout the motion of rocker arm 103A.

[0095] Figs. 16-17 illustrate an internal combustion engine 100E that includes a valvetrain 104E having a rocker arm assembly 106E. Fig. 15 provides a prospective view of rocker arm assembly 106E. Rocker arm assembly 106E may be a switch rocker arm including an inner arm 103D and an outer arm 103C. A cam follower 1 11 mounted to inner arm 103C may be configured to engage cam 107. Cam followers 198, which may be sliders, may be configured to engage additional cams (not shown) to provide an alternate valve lift profile from the one provided by cam 107. An electromechanical latch assembly 122 having a coil 1 19 may be mounted to inner arm 103D.

[0096] Referring to Figs. 16-18, coil 1 19 may be powered through an electrical circuit 105E that includes an electrical connection 108E that is formed between a conductive inlay 175E in valve 152 and pogo pin 110E mounted to cylinder head 102. Valve 152 is a load-bearing member of valvetrain 104E. Valve 152 transmits force between rocker arm 103D and valve spring 153.

[0097] Fig. 18 provides a schematic diagram for an example electrical circuit 105E. A part of electrical circuit 105E may be formed by a ribbon or coil of metal 188 making a connection between conductive inlay 187 and coil 1 19 mounted to inner arm 103D. Ribbon or coil of metal 188 may be relatively stiff. Coil 1 19 may be grounded to inner arm 103D.

[0098] As shown in Figs. 16 and 17, as valve 152 opens and closes, pogo pin 1 10E may slide up and down valve 152 while remaining in contact with conductive inlay 175E and keeping electrical connection 108E closed. Pogo pin 1 10E may be replaced by another type of part suitable for sliding along conductive inlay 175E while maintaining an electrical connection. Alternatives include, without limitation, motor brushes and spring clips. An alternative to conductive inlay 175E is a conductive trace on the surface of valve 152. Another alternative is to insulate valve 152 where it makes contact with other metal parts, whereby the body of valve 152 may be part of electrical circuit 105E. In each of these examples, a portion of electrical circuit 108E is rigidly coupled to and disposed along the length of the stem of valve 152.

[0099] Fig. 19 illustrates an internal combustion engine 100F that includes a valvetrain 104F having a rocker arm assembly 106F. An electromechanical latch assembly 122 including coil 119 may be mounted to inner arm 103D of rocker arm assembly 106F. Coil 1 19 may be powered through an electrical circuit 105F, for which Fig. 20 provides an example schematic diagram. Camshaft 109 may be mounted on dielectric bearings (not shown). Cam roller 1 11 may be mounted on dielectric bearings 114E. Circuit 105F connects coil 1 19 to power source 176 through brushes 11 OF, camshaft 109, cam 107, cam roller 11 1 , and brushes 110G. Circuit 105E includes camshaft 109, cam 107, and cam roller 1 11 , which may be maintained at potentials above or below that of cylinder head 102.

[0100] Electrical circuit 105F includes three connections formed by abutting surfaces of distinct parts that undergo relative motion in connection with actuation of cam follower 11 1. These are electrical connection 108F formed between camshaft 109 and brushes 1 1 OF, electrical connection 108H formed between cam 107 and cam roller 11 1 , and electrical connection 108G formed between cam roller 1 11 and motor brushes 110G, which may be mounted to inner arm 103D.

[0101] The internal combustion engines 100 all have end pivot overhead cam (OHC) type valvetrains 104. But the present teaching are generally applicable to internal combustion engines having other types of valvetrains 104 including, for example, other types of OHC valvetrains and overhead valve (OHV) valvetrains. As used in the present disclosure, the term "rocker arm assembly" may refer to any assembly of components that is structured and positioned to actuate a valve 152 in response to rotation of a camshaft 109.

[0102] Electrical circuits 105 formed with electrical connections 108 may be used to power or communicate with any suitable type of electronic device mounted to a rocker arm assembly 106. Fig. 21 provide a diagram for an example electrical circuit 105H including an electrical connection 108 through which a sensor 185 mounted to a mobile portion of a rocker arm assembly 106 may communicate with a device mounted off rocker arm assembly 106, such as an engine control unit (ECU) 186. That information may be used for diagnostics or control. In some of these teachings, sensor 185 is a device that does not require external power. Sensor 185 may be, for example, an accelerometer.

[0103] The components and features of the present disclosure have been shown and/or described in terms of certain embodiments and examples. While a particular component or feature, or a broad or narrow formulation of that component or feature, may have been described in relation to only one embodiment or one example, all components and features in either their broad or narrow formulations may be combined with other components or features to the extent such combinations would be recognized as logical by one of ordinary skill in the art.

Claims

The claims are:

1. A valvetrain for an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, and a camshaft, the valvetrain comprising:

a rocker arm assembly comprising a rocker arm and a cam follower configured to engage a cam mounted on a camshaft as the camshaft rotates;

an electrical circuit comprising an electrical device mounted to the rocker arm; wherein the electrical circuit includes an electrical connection made by abutment between surfaces of two distinct parts; and

the rocker arm assembly is operative to move one of the two abutting surfaces relative to the other in response to actuation of the cam follower.

2. A valvetrain according to claim 1 , wherein the electrical connection is isolated from ground.

3. A valvetrain according to any one of claims 1 to 2, wherein:

the rocker arm assembly is operative to form a force transmission pathway between a cam and a moveable valve; and

the force transmission pathway includes the rocker arm.

4. A valvetrain according to any one of claims 1 to 3, wherein one of the two distinct parts is mounted to the rocker arm assembly and the other is not.

5. A valvetrain according to any one of claims 1 to 3, wherein each of the two distinct parts is mounted to the rocker arm assembly.

6. A valvetrain according to any one of claims 1 to 5, wherein all or part of a load- bearing member of the valvetrain forms a part of the electrical circuit that is electrically isolated from ground.

7. A valvetrain according to claim 6, wherein the load-bearing member is a pivot providing a fulcrum for the rocker arm.

8. A valvetrain according to claim 7, wherein the pivot is a hydraulic lash adjuster.

9. A valvetrain according to any one of claims 1 to 8, wherein the electrical connection is formed across a load-bearing interface between two load-bearing members of the valvetrain.

10. A valvetrain according to any one of claims 1 to 8, wherein:

one of the two distinct parts is mounted to the rocker arm; and

the rocker arm is operative to pivot in response to actuation of the cam follower by a camshaft-mounted cam; and

the pivoting is operative to cause one of the two distinct parts to move relative to the other.

11. A valvetrain according to claim 10, wherein at least one of the surfaces forming the electrical connection is approximately perpendicular to an axis of the pivoting or rotation.

12. A valvetrain according to claim 10 or 11 , further comprising:

a lash adjuster providing a fulcrum for the rocker arm;

wherein at least one of the surfaces forming the electrical connection is approximately parallel to a direction in which the lash adjuster extends to provide lash adjustment.

13. A valvetrain according to claim 10, wherein:

at least one of the surfaces forming the electrical connection has a radius of curvature approximately equal to the surface's distance from the axis about which the pivoting occurs; and

the surface is oriented such that a line through a vector normal to the surface intersects or nearly intersects the axis.

14. A valvetrain according to any one of claims 1 to 9, wherein the rocker arm assembly is operative to cause one of the two distinct parts to roll across the other.

15. A valvetrain according to any one of claims 1 to 9, further comprising a spring biasing one of the two distinct parts against the other.

16. A valvetrain according to any one of claims 1 to 9, wherein one of the two distinct parts is mounted to a pivot that provides a fulcrum for the rocker arm.

17. A valvetrain according to any one of claims 1 to 16, further comprising a processor operatively coupled to communicate with the electrical device through the electrical connection.

18. A valvetrain according to any one of claims 1 to 16, wherein the electrical connection couples the electrical device with a power source.

19. A valvetrain according to claim 18, wherein the electrical device is an

electromechanical latch assembly.

20. A valvetrain according to claim 19, wherein:

the electromechanical latch assembly comprises a latch pin moveable between first and second positions;

the first latch pin position provides a configuration in which the rocker arm assembly is operative to actuate a moveable valve in response to actuation of the cam follower by a camshaft-mounted cam to produce a first valve lift profile; and

in the second latch pin position provides a configuration in which the rocker arm assembly is operative to actuate the moveable valve in response to actuation of the cam follower by the camshaft-mounted cam to produce a second valve lift profile, which is distinct from the first valve lift profile, or the moveable valve is deactivated.

21. A valvetrain according to claim 20, wherein:

the electromagnetic latch assembly comprises a coil operable to actuate the latch pin between the first and the second positions; and

the electromagnetic latch assembly provides the latch pin with positional stability independently from the solenoid when the latch pin is in the first position and when the latch pin is in the second position.

22. A valvetrain according to claim 21 , wherein:

the electromagnetic latch assembly is operable with a DC current in a first direction to actuate the latch pin from the first position to the second positions; and the electromagnetic latch assembly is operable with a DC current in a second direction, which is a reverse of the first, to actuate the latch pin from the second position to the first position.

23. A valvetrain according to any one of claims 1 to 22, wherein the rocker arm assembly is operative to cyclically break the electrical connection in relation to actuation of the cam follower.

24. A valvetrain according to claim 23, wherein one of the two distinct parts is operative to form a second electrical connection over a period when it is not forming the first electrical connection.

25. A method of operating an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, a camshaft on which a cam is mounted, and a valvetrain according to any one of claims 1 to 23, the method comprising:

determining the status of the electrical connection; and

performing an engine management or diagnostic operation based on one or more of the status determinations.

26. A method of operating an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, a camshaft on which a cam is mounted, and a valvetrain according to claim 24, the method comprising:

determining the status of the second electrical connection; and

27. A method of operating an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, a camshaft on which a cam is mounted, and a valvetrain according to claim 24, the method comprising:

determining the status of the first electrical connection;

determining the status of the second electrical connection; and performing an engine management or diagnostic operation based on one or more of the status determinations.

28. A method of operating an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, a camshaft on which a cam is mounted, and a valvetrain according to claim 24, the method comprising:

determining the statuses of the first and second electrical connection; and using the information to perform an engine management or diagnostic operation.

29. A method according to claim 25 or claim 26, wherein using the information to perform an engine management or diagnostic operation affects management of the engine.

30. A method according to claim 25 or claim 26, wherein using the information to perform an engine management or diagnostic operation comprises providing a diagnostic report based on the information.

31. An internal combustion engine comprising:

a combustion chamber;

a moveable valve having a seat formed in the combustion chamber;

a camshaft; and

a valvetrain according to any one of claims 1 to 24;

wherein the abutting surfaces of the two distinct parts are electrically isolated from the combustion chamber.