A method of providing diagnostic information for an electromagnetic latch assembly (122) includes providing a pulse to a circuit (200) that include one or more electromagnetic latch assemblies. The circuit (200) includes coils (199) of the electromagnetic latch assemblies. Each coil is inductively coupled with an armature (131) that is mechanically coupled to a latch pin (118). The circuit (200) is pulsed and a DC current in the circuit (200) that results from the pulse is measured over a first interval to determine a primary response. The current in the circuit (200) over a second interval is measured to determine a reference response. A second pulse may be used to generate the current for the reference response. The primary response and the reference response are compared to provide diagnostic information relating to position or movement of one or more of the latch pins (118).

A method of providing diagnostic information for an electromagnetic latch assembly (122) includes providing a pulse to a circuit (200) that include one or more electromagnetic latch assemblies. The circuit (200) includes coils (199) of the electromagnetic latch assemblies. Each coil is inductively coupled with an armature (131) that is mechanically coupled to a latch pin (118). The circuit (200) is pulsed and a DC current in the circuit (200) that results from the pulse is measured over a first interval to determine a primary response. The current in the circuit (200) over a second interval is measured to determine a reference response. A second pulse may be used to generate the current for the reference response. The primary response and the reference response are compared to provide diagnostic information relating to position or movement of one or more of the latch pins (118).

A valvetrain includes a rocker arm assembly having a rocker arm and an electromagnetic latch assembly. An electromagnet of the latch assembly is housed within a chamber formed by the rocker arm. Passageways suitable for oil cooling of the electromagnet are formed through and inside the rocker arm. In some embodiments, oil for cooling is supplied through a pivot. In some embodiments, oil for cooling is obtained from oil splash. Oil cooling may allow modes of operation such as of dynamic cylinder deactivation and dynamic variable valve actuation to be used without overheating the electromagnet.

A valvetrain includes a rocker arm assembly having a rocker arm and an electromagnetic latch assembly. An electromagnet of the latch assembly is housed within a chamber formed by the rocker arm. Passageways suitable for oil cooling of the electromagnet are formed through and inside the rocker arm. In some embodiments, oil for cooling is supplied through a pivot. In some embodiments, oil for cooling is obtained from oil splash. Oil cooling may allow modes of operation such as of dynamic cylinder deactivation and dynamic variable valve actuation to be used without overheating the electromagnet.

A variable valve mechanism includes an input arm that axially supports a roller pressed by a cam, via a roller pin, an output arm that drives a valve when swinging, a switch device that switches the variable valve mechanism between a coupled state where the both arms are coupled and an uncoupled state where the arms are uncoupled from each other, and a lost motion spring that biases the roller against the cam when in the uncoupled state. The lost motion spring includes an extended portion extending in an inter-arm clearance between the input arm and the output arm. An end of the roller pin projects from the input arm into the inter-arm clearance by such a length that the end is accommodated in the inter-arm clearance and that allows a spring retaining portion to be formed in the end. The spring retaining portion is formed in the end.

A lost motion mechanism can comprise a castellation device, comprising a casing, an upper castellation, and a lower castellation. The casing can comprise a first linear slot and a second linear slot perpendicular to the first linear slot. Upper castellation can comprise an upper body, spaced upper teeth extending from the upper body, the spaced upper teeth forming spaced upper gaps therebetween, and an actuation peg extending from the upper body into the first linear slot. Lower castellation can comprise a lower body, spaced lower teeth extending from the lower body, the spaced lower teeth forming spaced lower gaps therebetween, and an anti-rotation peg extending from the lower body into the second linear slot. An actuator can be configured with the lost motion mechanism so that a movable arm comprises a forked end configured to move on the actuation peg as the movable arm swivels.

A lost motion mechanism can comprise a castellation device, comprising a casing, an upper castellation, and a lower castellation. The casing can comprise a first linear slot and a second linear slot perpendicular to the first linear slot. Upper castellation can comprise an upper body, spaced upper teeth extending from the upper body, the spaced upper teeth forming spaced upper gaps therebetween, and an actuation peg extending from the upper body into the first linear slot. Lower castellation can comprise a lower body, spaced lower teeth extending from the lower body, the spaced lower teeth forming spaced lower gaps therebetween, and an anti-rotation peg extending from the lower body into the second linear slot. An actuator can be configured with the lost motion mechanism so that a movable arm comprises a forked end configured to move on the actuation peg as the movable arm swivels.

A high-pressure oil pump roller tappet, used for automobile fuel injection system, mounted between the driving cam and the tappet. The roller tappet includes a shell, a holder, a roller, and a pin. Planes A are arranged on both sides of the seam on lateral sides of the shell. Holes I are arranged at symmetrical positions on two planes A. Holes II are arranged on symmetrical positions on vertical plates. The roller is located in the middle of the pin. Welding has no requirement on the thickness of the plate. The weight can be controlled effectively, reducing inertia force, friction, and wear, improving engine efficiency. The shell and holder are designed as being separate, ensuring that the shell subjects to lateral force as little as possible when the holder subjects to a force, such that the shell is less likely to vibrate. Thus, the shell avoids the abrasion.

A high-pressure oil pump roller tappet, used for automobile fuel injection system, mounted between the driving cam and the tappet. The roller tappet includes a shell, a holder, a roller, and a pin. Planes A are arranged on both sides of the seam on lateral sides of the shell. Holes I are arranged at symmetrical positions on two planes A. Holes II are arranged on symmetrical positions on vertical plates. The roller is located in the middle of the pin. Welding has no requirement on the thickness of the plate. The weight can be controlled effectively, reducing inertia force, friction, and wear, improving engine efficiency. The shell and holder are designed as being separate, ensuring that the shell subjects to lateral force as little as possible when the holder subjects to a force, such that the shell is less likely to vibrate. Thus, the shell avoids the abrasion.

Systems and methods for operating exhaust valves of an internal combustion engine with poppet exhaust valves are described. The systems and methods provide for locking exhaust valves in a closed state when the exhaust valves are in mechanical communication with a base circle of a camshaft lobe. Locking the exhaust valves in a closed state may reduce the possibility of exhaust pressures opening the exhaust valves at times they may not be desired to be open.