Patent Grant
11008900
The present teachings relate to valvetrains, particularly valvetrains providing variable valve lift (VVL) or cylinder deactivation (CDA).
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.
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.
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. The present teachings provide 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.
According to some aspects of the present teachings, an electrical circuit that of which the electrical device is a part includes a connection formed by abutment between the 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. The abutting surfaces of the two distinct parts may be electrically isolated from ground, whereby 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.
According to some aspects of the present teachings, one of the two distinct parts forming the electrical connection is mounted to the rocker arm assembly and the other is not. In some of these teachings the part mounted to the rocker arm assembly is mounted to the rocker arm on which the electrical device is mounted. In some of these teachings, the part not mounted to the rocker arm assembly is mounted to a frame that has a base that fits against a pivot that provides a fulcrum for the rocker arm assembly. In some of these teachings, the frame fits around a pivot that provides a fulcrum for the rocker arm assembly. In some of these teachings, the frame also rests against a cylinder head in which the combustion chamber is formed. In some of these teachings, the frame rests against the cylinder head at a point on the cylinder head that is higher above the combustion chamber than the rocker arm assembly and at a point on the cylinder head that is less high above the combustion chamber than the rocker arm assembly. In some of these teachings, the part not mounted to the rocker arm assembly is mounted to a frame that has a base that abuts two or more pivots that provide fulcrums for rocker arm assemblies of the valvetrain.
In some of these teachings, one of the two distinct parts that forms the electrical connection is mounted to the 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 or in abutment with 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.
According to some aspects of the present teachings, a load-bearing member of the valvetrain forms part of the electrical circuit. In some of these teachings, the portion of the load-bearing structure that forms a portion of the electrical circuit is isolated from ground. In some of these teachings, the load-bearing structure is a pivot. In some of these teachings, the load-bearing structure is a cam. In some of these teachings, the load-bearing structure is a cam follower. In some of these teachings, the electrical connection is formed at a load-bearing interface between two structures of the valvetrain.
In some of these teachings, the electrical device is powered through the electrical circuit. In some of these teachings, the electrical device is an electromagnetic latch assembly. 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 a sensor.
According to some aspects of the present 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. In some of these teachings, the electrical connection is made proximate the axis of pivoting. Forming the connection near the axis of pivoting keeps motion between the two distinct parts comparatively small. In some of these teachings, one of the parts forming the electrical connection is mounted over a spring post on the rocker arm. The spring post may be located proximate the axis of pivoting.
In some of these teachings, one of the surfaces forming the electrical connection is oriented parallel to a plane to which the axis of pivoting is perpendicular. 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 a lash adjuster extends to adjust lash.
In some others of these teachings, one of the two part surfaces has a surface normal vector that points approximately toward or directly away from the axis about which the pivoting occurs. In some of these other 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. The foregoing structures 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.
According to some aspects of the present teachings, one of the two distinct parts is a contact held to a side of the rocker arm by a contact frame that is supported within an opening at the back of the rocker arm. In some of these teaching, the contact frame is secured to the sides of the rocker arm as well.
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.
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. Brushes 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.
According to some aspects of the present teachings, a lash adjuster provides a fulcrum on which the rocker arm assembly pivots. In some of these teachings, one of the surfaces forming the electrical connection runs parallel to a direction in which the lash adjuster extends to adjust lash. In some of these teachings, the surfaces of the two distinct parts forming the electrical connection are configured to slide one past the other while remaining in contact as the lash adjuster extends and retracts to adjust lash. In some of these teachings, the lash adjuster is a hydraulic lash adjuster and the surfaces of the two distinct parts forming the electrical connection are configured to maintain the electrical connection as the lash adjuster extends and retracts between pumped up and depressurized states. 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.
According to some aspects of the present teachings, the valvetrain 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. In some of these teachings, the spring is a leaf spring. In some of these teachings, an end of the leaf spring is held stationary relative to the combustion chamber.
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, the electrical circuit is completed by a mechanical interface between two load bearing structures of the valvetrain. In some of these teachings, one of the two parts 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.
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. In some of these teachings, the load-bearing member is a pivot.
In some of these teachings, the electrical device is an electromagnetic 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).
In some of these teachings, the electromagnetic latch assembly include a coil operable to actuate the latch pin between the first and second positions. In some of these teachings the electromagnetic latch assembly provides the latch pin with positional stability independently from the coil 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.
According to some other aspects of the present teachings, the coil or a permanent magnet forming part of the electromagnetic latch assembly is rigidly mounted to the rocker arm and the electromagnetic latch assembly provides the latch pin with positional stability independently from the coil when the latch pin is in the first position and when the latch pin is in the second position. This dual positional stability enables the latch to retain both latched and unlatched states without reliance on the coil. The coil then does not need to be powered and need not be operative on the latch pin except for latch pin actuation, which may be limited to times at which the cam is on base circle. This can facilitate the implementation of an electromagnetic latch assembly a portion which is mounted on a rocker arm that moves rapidly at times over the course of its operating cycle. Installing a significant portion of an electromagnetic latch assembly, including at least the coil or a permanent magnet, on the rocker arm can provide a more compact design as compared to one in which an electromagnetic latch assembly is mounted off the rocker arm.
According to some aspects of the present teachings, a permanent magnet contributes to the positional stability of the latch pin both when the latch pin is in the first position and when the latch pin is in the second position. According to some further aspects of these teachings, the electromagnetic latch assembly is structured to operate through a magnetic circuit shifting mechanism. In some of these teachings, absent any magnetic fields generated by the electromagnet or other external sources, when the latch pin is in the first position, an operative portion of the magnetic flux from the permanent magnet follows a first magnetic circuit and when the latch pin is in the second position, an operative portion of the magnetic flux from the permanent magnet follows a second magnetic circuit distinct from the first magnetic circuit. The coil may be operative to redirect the permanent magnet's flux away or toward one or the other of these magnetic circuits and thereby cause the latch pin to actuate. In some of these teachings redirecting the magnetic flux includes reversing the magnetic polarity in a low coercivity ferromagnetic element forming part of both the first and second magnetic circuits. An electromagnetic latch assembly structured to be operable through a magnetic circuit shifting mechanism may be smaller than one that is not so structured. In some of these teachings, the permanent magnet is fixedly mounted to the rocker arm. Fixing the permanent magnet to the rocker arm means not fixing the permanent magnet to the latch pin. Taking the weight of the permanent magnet off the latch pin may increase actuation speed and allow the use of a smaller coil.
In some of these teaching, the coil encircles a volume within which a portion of the latch pin comprising low coercivity ferromagnetic material translates and the electromagnetic latch assembly comprises one or more sections of low coercivity ferromagnetic material outside the volume encircled by the coil. Both the first and the second magnetic circuits pass through the latch pin portion formed of low coercivity ferromagnetic material. In some of these teachings, the first magnetic circuit passes around the outside of the coil via the one or more sections of low coercivity ferromagnetic material while the second magnetic circuit does not pass around the outside of the coil. This characteristic of the second magnetic circuit reduces magnetic flux leakage and increases the holding force per unit mass provided by the permanent magnet when the latch pin is in the second position.
In some of these teachings, the electromagnetic latch assembly includes a second permanent magnet distal from the first and fulfilling a complimentary role. The electromagnetic latch assembly may provide two distinct magnetic circuits for the second permanent magnet, one or the other of which is the path taken by an operative portion of the magnet flux from the second permanent magnet depending on the whether the latch pin is in the first position or the second position. The path taken when the latch pin is in the second position may pass around the outside of the coil via the one or more sections of low coercivity ferromagnetic material. The path taken when the latch pin is in the first position may be a shorter path that does not pass around the outside of the coil. One or the other of the permanent magnets may then provide a high holding force depending on whether the latch pin is in the first or second positions. In some of these teachings, both permanent magnets contribute to the positional stability of the latch pin in both the first and the second latch pin positions. In some of these teachings, the two magnets are arranged with confronting polarities. In some of these teachings, the two magnets are located at distal ends of the volume encircled by the coil. In some of these teachings, the permanent magnets are annular in shape and polarized along the directions of the axes. These structures may be conducive to providing a compact and efficient design.
In some of these teachings, the electromagnetic latch assembly includes two permanent magnets arranged with confronting polarities and with a pole piece of magnetically susceptible material between them. In some of these teachings, the magnetically susceptible material is a low coercivity ferromagnetic material. The magnets and the pole piece are fixed to the rocker arm and arranged about an opening through which the latch pin translates. In some of these teaching, the pole piece bounds the opening. The permanent magnets may also bound the opening. In some of these teachings, the pole piece bounds the opening more narrowly than the magnets, whereby the latch pin contacts the pole piece but does not contact either of the magnets. In this configuration, the pole piece helps secure the latch pin against rocking while the permanent magnets are relieved of stress.
A shell surrounding the coil may have an opening through which the latch pin extends. In accordance with some aspects of the present teachings, the latch pin has a non-circular profile where it passes through that opening. The shape of the opening cooperates with the latch pin profile to restrict rotation of the latch pin. This structure provides an anti-rotation function and facilitates smooth operation of the latch pin, particularly when the latch pin is supported within the coil.
In some of the present teaching, the electromagnetic latch assembly includes at least one permanent magnet and the internal combustion engine has circuitry operable to energize the coil with a current in either a first direction or a second direction, which is the reverse of the first direction. A latch having dual positional stability may require the coil current to be in one direction for latching and the opposite direction for unlatching. The coil powered with current in the first direction may be operative to actuate the latch pin from the first position to the second position. The coil powered with current in the second direction may be operative to actuate the latch pin from the second position to the first position. In some others of these teachings, the electromagnetic latch assembly include two coils, one for latching and the other for unlatching. The two coils may have windings in opposite directions. Employing two coil may allow for the control circuitry to be more robust. Employing only one coil may provide the most compact design.
According to some aspects of the present teachings, the rocker arm assembly is operative to cyclically break or vary the resistance of 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, a surface of one of the parts forming the electrical connection is partially coated with a material that increases electrical resistance and the valvetrain is operable to move the area of contact between the two distinct parts between the coated surface and an uncoated surface, whereby the resistance of the connection varies in conjunction with rocker arm motion. 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 onboard 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.
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.
In some aspects of the present teachings, the rocker arm has external wiring that runs from the side of the rocker arm to the back of the rocker arm. A portion o an electromagnetic latch assembly including a coil may be installed in the rocker arm through the opening at the back. A latch pin may extend out of the rocker arm at the opposite side from the opening. In some of these teachings, wiring to the coil passes through the opening in the back of the rocker arm. In some of these teachings, external wiring running from the back of the rocker arm to the side of the rocker arm is supported by a part that is mounted within the opening in the back of the rocker arm. In some of these teachings, the part is press fit within that opening. In some of these teachings, the part is formed by over-molding the wiring. In some of these teachings, the part holds contact pads to the sides of the rocker arm. An electrical connection to the rocker arm may be made through the contact pads. The contact pads may have contact surfaces oriented in a plane. Rocker arm motion may be limited to directions all of which lie in a plane parallel to the plane in which the contact pads are oriented.
According to some aspects of the present teachings, the rocker arm assembly includes a pivot and a wiring connection to the rocker arm is made from a wiring harness that abuts the pivot. The pivot may be a hydraulic lash adjuster. Abutment with the pivot facilitates correct positioning of the wiring harness and connectors between the wiring harness and the rocker arm. In some of these teachings, the wiring harness abuts a plurality of pivots and provides connections to rocker arms associated with each of those pivots.
According to some aspects of the present teachings, the valvetrain includes a wiring harness providing power to the valvetrain. In some of these teachings the wiring harness connects to the power system of a vehicle. In some of these teachings the wiring harness connects to a vehicle control system. In some of these teachings, a wiring connection to the vehicle is made proximate a spark plug tower. In some of these teachings, the wiring runs through the valve cover proximate the spark plug tower. In some of these teachings, the wiring runs into the spark plug tower below the valve cover and out of the spark plug tower above the valve cover.
In some of these teachings, the wiring harness is supported by a frame. In some of these teachings, the frame is plastic. In some of these teachings, the wiring harness include wires that are fully enclose in the plastic frame. In some of these teachings, wires fully enclosed in the plastic frame are formed by strips of metal. The plastic frame may protect the wiring from the surrounding environment, prevent the wiring from contacting moving parts, and prevent the wiring from being damaged during maintenance.
In some of these teachings, the frame rests on the cylinder head. In some of these teachings, the frame is secured to the cylinder head. The frame may maintain the wiring in proximity to the cylinder head, where the wiring is out of the way. In some of these teachings, the frame supports or incorporates towers that include spring loaded connectors that slide over contacts on the rocker arms to complete electrical circuits that power the electromagnetic latch assemblies.
In some of these teachings, the frame abuts a spark plug tower. In some of these teachings, the frame has a circular opening that fits around a spark plug tower. In some of these teachings, the frame fits closely around a spark plug tower. These features may be provided to help locate the frame.
In some of these teachings, the frame abuts a pivot that provides a fulcrum for a rocker arm assembly. In some of these teachings, the pivot is a lash adjuster. The lash adjuster may be a hydraulic lash adjuster. The frame may mount against the pivot. In some of these teachings, the location of the frame is secured by the pivot. In some of these teachings, the location of the frame is secured by both a pivot and a spark plug tower. The frame may be braced against the pivot and the spark plug tower. Locating the frame against a pivot may facilitate properly positioning wiring and contacts that complete circuits with electronic devices mounted to the pivot or the rocker arm assembly.
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.
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.
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 therefore 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.
With reference to
Electromagnetic latch assembly 122 includes a coil 119. Coil 119 may be rigidly mounted with respect to outer arm 103A. Electromagnetic latch assembly 122 may include permanent magnets 120A and 120B, a latch pin 115, and a shell 116. 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 118 and a low coercivity ferromagnetic portion 123. Low coercivity ferromagnetic portion 123 may be a sleeve on an otherwise paramagnetic latch pin 115. Latch pin 115 may be translatable between extended and retracted positions.
If cam 107 is rotated while latch pin 115 is in the non-engaging position as shown in
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.
Shell 116 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 electromagnetic 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 or part of this same function. Shell 116 may wrap around the outside coil 119 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 119 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 115 is actuated.
Electromagnetic 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 115 to remain in and return to a particular position. Stability is provided by restorative forces that act against small perturbations of latch pin 115 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 115 from a stable position. Alternatively, or in addition, one or more springs may be positioned to provide positional stability.
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 electromagnetic 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 119.
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 119 may reverse the magnetic polarity in low coercivity ferromagnetic elements such as shell 116, ring 121, and sleeve 123 that form low reluctance magnetic pathways through which permanent magnets 120 stabilize latch pin 115 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 115 may drive it to the retracted position.
While permanent magnets 120 may initially hold latch pin 115 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 that point, the pathways for magnetic flux from permanent magnets 120 have shifted. Beyond that point, coil 119 may be disconnected from its power source and latch pin 115 may still complete its travel to the retracted position.
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 115 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 115 may drive it to the extended position. At some point during latch pin 115's progress toward the extended position, permanent magnets 120 begin to attract latch pin 115 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.
As used herein, a permanent magnet is a high coercivity ferromagnetic material with residual magnetism. A high coercivity means that the polarities of permanent magnets 120 remain unchanged through hundreds of operations through which electromagnetic latch assembly 122 is operated to switch latch pin 115 between the extended and retracted positions. Examples of high coercivity ferromagnetic materials include compositions of AlNiCo and NdFeB.
Coil 119 may be powered through an electrical circuit 105A that includes one or more electrical connections 108A formed by contact between pogo pins 110A and contact pads 175A.
In some alternative embodiments, electromagnetic latch assembly 122 includes two coils 119 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 electromagnetic latch assembly 122. One of the circuits 105A may be closed to actuate latch pin 115 in a first direction and the other to actuate latch pin 115 in the reverse direction.
The portion of circuit 105A that includes electrical connection 108A is electrically isolated from ground 172 and cylinder head 102, which may be at the same potential. Electrical connection 108A may be made by surface contact between pogo pin 110A 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 110A 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 110A.
With reference to
Rocker arm 103A is operative to pivot on HLA 140, which provides a fulcrum. The motion of rocker arm 103A is substantially constrained to 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 110A 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 110A may be fit with a roller and roll over contact pad 175A as rocker arm 103A pivots.
Contact pad 175A may be mounted over 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
In engine 100K, an electrical connection 108K may be formed between contact pins 175K mounted to rocker arm 103A and motor brushes 110K mounted to a part distinct from rocker arm 103A. Motor brushes 110K may be held by a mounting frame 132K in a position where they are biased against and slide over contact pins 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 held by frame 132K. Wiring harness 168 may include a plurality of wires 173 that connect to motor brushes 110K, whereby wiring harness 168 may carry power or communication signals for coil 119 or other electrical devices on a plurality of rocker arm assemblies 106K.
With reference to
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.
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 191B 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 valvetrain 104B 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.
Valvetrain 104B may be operative to move rocker arm 103A through a range of motion. That 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 110B may be of a type used in motors.
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.
A current measuring device 193 may be provided to detect the forming and breaking of electrical connection 1086. As illustrated in
In some aspects of the present teachings, a second contact pad 175C is also mounted to rocker arm 103A. As shown in
A voltage may be applied to circuit 105C at a time when actuation of latch pin 115 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 115 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.
Contact pads 175B and 175C are mounted to rocker arm 103A on a projecting structure 151. Projecting structure 151 supports contacts pads 1756 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 1106 and surface 150 remains nearly constant as rocker arm 103A pivots through it range of motion. This structure facilitates motor brushes 1106 making contact first with contact pad 1756 and then with contact pad 175C as rocker arm 103A pivots through it range of motion. If contact pad 1756 were extended along surface 150, this same structure could be used to maintain contact between motor brushes 1106 and contact pad 1756 throughout the range of motion of rocker arm 103A.
Electrical connections 108D may be formed by surface contact between first parts 110D mounted to HLA 140 and second parts 175D mounted to rocker arm 103A. Parts 110D 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 110D may include sprung members biasing them into contact. Insulating layer 171 may be formed from any suitable material.
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 electromagnetic 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.
Engine 100D is an example in which an electrical connection 108 is formed by abutment between a first part 110 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
Hydraulic lash adjuster 140G may be insulated from cylinder head 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.
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
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 110L 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.
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 110 and 175 may then be configured to abut and form electrical connection 108. Engine 100M of
With reference to
With reference to
Referring to
As shown in
Electrical circuit 105F includes three connections formed by abutting surfaces of distinct parts that undergo relative motion in connection with actuation of cam follower 111. These are electrical connection 108F formed between camshaft 109 and brushes 110F, electrical connection 108H formed between cam 107 and cam roller 111, and electrical connection 108G formed between cam roller 111 and motor brushes 110G, which may be mounted to inner arm 103D.
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.
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.
Valvetrain 400 further includes a framework 420A that holds spring loaded pins 407A and 407B against contact pads 404A and 404B respectively, at least when rocker arm 103A is on base circle. As shown in
With reference to
In some of these teachings, spring loaded pin 407B remains in abutment with contact surface 405B throughout rocker arm 103A's range of motion. In some of these teachings, spring loaded pin 407A remains in abutment with contact surface 405A through only a portion of rocker arm 103A's range of motion. Contact pad 404A may be structured and positioned such that as rocker arm 103A is lifted off base circle, spring loaded pin 407A moved from abutment with contact surface 405A to abutment with contact surface 405C. Connection through contact surface 405C may present a distinctly higher resistance than connection through contact surface 405A. The higher resistance may be provided by a coating on contact surface 405C that is not present on contact surface 405A. In some of these teachings, that coating is a diamond-like carbon (DLC) coating. The difference in resistance may be used to detect the position of rocker arm 103A.
Latch pin 115 may be installed in rocker arm 103A through opening 408 at the back of rocker arms 103A. Coil 119 is also installed in rocker arm 103A through opening 408. Wires 413, which couple coil 119 to contact pads 404, run out of rocker arm 103A through opening 408. Wires 413 continue around the side of rocker arm 103A to connect with contact pads 404. In some of these teachings, wires 413 and contact pads 404 are supported by a bracket 409 that mounts to rocker arm 103A within opening 408.
As shown in
As shown in
As shown in
As shown in
Rocker arm assemblies 1060 each include two pivotally connected rocker arms 103E and 103F. As shown in
Power transfer module 223 includes leaf springs 215. Leaf springs 215 are electrical conductors. Power transfer module 223 is designed to hold leaf springs 215 in abutment with contact pins 212. Electrical connections through which coil 119 may be powered are made between contact pins 212 and leaf springs 215. There may be two electrical connection to each rocker arm 103E, the two connections being made on opposite sides of the rocker arm 103E. Electrical contact may be maintained even as contact pins 212 slide over the surfaces of leaf springs 215 in connection with normal operation of rocker arm assemblies 1060.
Rocker arm assemblies 1060 are configured to undergo a pivoting motion as they are actuated by cams 107 (see
On the other hand, in some of these teachings, a certain range of motion between contact pins 212 and leaf springs 215 is desirable. A portion of the surface of a leaf spring 215 may be coated with a material that significantly increase the resistance of an electrical circuit comprising a connection between contact pin 212 and leaf spring 215. Contact pin 212 may move to that high resistance surface only when cam 107 is lifting rocker arm 103E. The increase in resistance may be detected and used to provide rocker arm position information, which in turn may be used in diagnostic or control operations.
As can be seen in
A connection plug 219 may be positioned at the top of power transfer module 223. Connection plug 219 may be used to couple power transfer module 223 to a vehicle's electrical system. An elevated location such as this, which may be above the heights of rocker arm assemblies 1060, facilitates the coupling with the vehicle's electrical system in that wires connecting to connection plug 219 have a short distance to travel before passing through the valve cover (not shown). The wires may pass through the valve cover adjacent a spark plug tower. One option is to run the wires into and out of a spark plug tower in order that they pass through the valve cover within a spark plug tower.
Power transfer module 223 has a lower portion 241 that rests against cylinder head 102 adjacent pivot 140 and an upper portion 243 that fits over and may rest on a raised portion 245 of cylinder head 102. Raised portion 245 may be above rocker arm assembly 106. “Above” is used in the sense that rocker arm assembly 1060 is “above” a combustion chamber formed within cylinder head 102. Power transfer module 223 has openings 239 that fit around pivots 140. Openings 239 abut pivots 140 and help locate power transfer module 223. Openings 239 may fit tightly around pivots 140, whereby pivots 140 may by joined to power transfer module 223 prior to installation. Openings 233 may be formed in lower portion 241 of power transfer module 223 and used to bolt power transfer module 223 to cylinder head 102.
Contact frame 224 may be press fit with an opening 226 through which electromagnetic latch assembly 122 is installed within rocker arm 103E. Contact frame 224 may also be held to the sides of rocker arm 103E. In this example, contact frame 224 is bolted to the sides of rocker arm 103E. Alternatively, support at the sides of rocker arm 103E may be provided by piloting contact pins 212 to the sides of rocker arm 103E. Insulation may prevent short circuiting between a contact pin 212 and rocker arm 103E although this structure without insulation could be used to form a connection to ground.
Method 900 continues with action 903, energizing coil 119 with a current in a forward direction to alter the circuit taken by flux from first permanent magnet 200A and cause latch pin 115 to translate to a second position. Energizing coil 119 with a current in a forward direction may also alter the circuit taken by flux from a second permanent magnet 200B. Action 903 may be initiated by an automatic controller. In some of these teachings, the controller is an ECU.
Following translation of latch pin 115 to the second position through action 903, coil 119 may be disconnected from its power source with action 905. Method 900 then continues with action 907, holding latch pin 115 in the second position using a magnetic field generated by a first permanent magnet 200A and following a magnetic circuit 162 that does not encircles the windings of coil 119. This may be a short magnetic circuit with low magnetic flux leakage. In some of these teachings, action 907 further includes holding latch pin 115 in the second position using a magnetic field generated by a second permanent magnet 200B and following a magnetic circuit 164 that encircles the windings of coil 119.
Method 900 may continue with action 909, energizing coil 119 with a current in a reverse direction to again alter the circuit taken by flux from first permanent magnet 200A. Action 909 causes latch pin 115 to translate back to the first position. Energizing coil 119 with a current in a reverse direction may also alter the circuit taken by flux from a second permanent magnet 1906. Action 909 also may be initiated by an automatic controller, such as an ECU. Action 911 may then be carried out, which is again de-energizing coil 119. The actions of method 900 may subsequently repeat.
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.
The present application is a divisional of U.S. patent application Ser. No. 16/460,886 filed Jul. 19, 2019, which is a divisional of U.S. patent application Ser. No. 15/863,901 filed Jan. 6, 2018, which claims priority from U.S. Provisional Patent Application No. 62/259,764 filed Nov. 25, 2015, U.S. Provisional Patent Application No. 62/305,612 filed Mar. 9, 2016, PCT Application PCT/US16/63730, filed Nov. 24, 2016, U.S. Provisional Patent Application No. 62/449,174, filed Jan. 23, 2017, U.S. patent application Ser. No. 15/503,458, filed Feb. 13, 2017, U.S. Provisional Patent Application No. 62/488,747, filed Apr. 22, 2017, and U.S. Provisional Patent Application No. 62/503,303, filed May 8, 2017, which applications are incorporated by reference in their entireties.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5544626 | Diggs | Aug 1996 | A |
| 20080127917 | Riley | Jun 2008 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20200300129 A1 | Sep 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62503303 | May 2017 | US | |
| 62488747 | Apr 2017 | US | |
| 62449174 | Jan 2017 | US | |
| 62305612 | Mar 2016 | US | |
| 62259764 | Nov 2015 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16460886 | Jul 2019 | US |
| Child | 16893823 | US | |
| Parent | 15863901 | Jan 2018 | US |
| Child | 16460886 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15503458 | Feb 2017 | US |
| Child | 15863901 | US | |
| Parent | PCT/US2016/063730 | Nov 2016 | US |
| Child | 15503458 | US |
