Systems, methods, and devices for valve stem position sensing

A system for measuring a position of a valve in an internal combustion engine, the system comprising:

• a valve guide having a central recess with a constant diameter passing through a length of the valve guide,
• wherein the valve of the internal combustion engine comprises:
• a valve stem including a first section comprising an armature with a first magnetic property adjacent to a second section with a second magnetic property and an interface between the first section and the second section, the first section, the second section and the interface comprising a single outer diameter less than the constant diameter of the valve guide,
• wherein the valve stem is received by the central recess and the valve stem is adapted to move linearly through the central recess;
• a powered coil surrounding the central recess of the valve guide;
• and
• a sensor coil also surrounding the central recess of the valve guide, the sensor coil adjacent the powered coil, wherein the valve stem is adapted to change a coupling between the sensor coil and the powered coil as the valve stem moves relative to the sensor coil and the powered coil, thereby generating a signal within the sensor coil that is directly related to a position of the valve stem relative to the sensor coil and the powered coils.

A system for measuring a position of a valve in an internal combustion engine, the system comprising:

• a valve guide having a central recess with a constant diameter passing through a length of the valve guide,
• wherein the valve of the internal combustion engine comprises:
• a valve stem including a first section having a first magnetic property adjacent to a second section having a second magnetic property and an interface between the first section and the second section, the first section, the second section and the interface comprising a single outer diameter less than the constant diameter of the valve guide,
• wherein the valve stem is received by the central recess and the valve stem is adapted to move linearly through the central recess;
• and
• a linear variable differential transformer (LVDT) located around the valve stem and adapted to generate a signal indicating motion of the valve stem,
• wherein the valve guide has an external recess and wherein windings of the LVDT are positioned within the external recess of the valve guide,
• wherein the valve further comprises a switching rocker arm assembly adapted to drive the valve, wherein the switching rocker arm assembly of the valve is adapted to drive the valve in a high lift mode or a low lift mode, wherein the high lift mode causes the valve stem interface to move through a first distance, and the low-lift mode causes the valve stem interface to move through a second distance smaller than the first distance.