# US 10,119,429 B2 · Systems, methods, and devices for valve stem position sensing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,119,429 B2 - Document ID: US10119429B2 - Status: Granted - Kind: B2 - Application number: 14/980,870 - Filed: 2015-12-28 - Published: 2016-05-19 - Granted: 2018-11-06 - Earliest claimed: 2010-03-19 - Assignees: Eaton Corporation - Applicants: Eaton Corporation - Inventors: Douglas John Nielsen; Mark William Hildebrandt - Web page: https://patentgrep.com/patent/US10119429B2 ## CPC - F01L 1/2405: {by means of a hydraulic adjusting device located between the cylinder head and rocker arm} - F01L 1/18: Rocking arms or levers - F01L 1/185: {Overhead end-pivot rocking arms} - F01L 3/08: Valves guides; Sealing of valve stem, e.g. sealing by lubricant - F01L 13/0005: {Deactivating valves} - F01L 13/0036: {the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction} - F02D 13/023: {the change of valve timing is caused by the change in valve lift, i.e. both valve lift and timing are functionally related} - F01L 2001/186: {Split rocking arms, e.g. rocker arms having two articulated parts and means for varying the relative position of these parts or for selectively connecting the parts to move in unison} - F01L 2301/00: Using particular materials - F01L 2305/00: Valve arrangements comprising rollers - F01L 2800/18: Testing or simulation - F01L 2820/01: Absolute values - F01L 2820/033: Hydraulic engines - F01L 2820/045: Valve lift - Y02T 10/12: Improving ICE efficiencies - F01L: CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A linear variable differential transformer (LVDT) for monitoring engine valve position is disclosed. The system includes a valve guide having an elongated recess through it. The engine valve has a valve head and a valve stem with two adjacent materials having different magnetic properties meeting at an interface. The valve stem fits and moves linearly within the valve guide, and the valve head closes an engine combustion chamber. It also includes monitoring coils within the valve guide that create a signal related to the position of the interface within the valve guide. An engine control unit (ECU) is coupled to the monitoring coils and receives and analyzes the signal from the monitoring coils to determine operation of the valve. ## Claims ### Claim 1 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. ### Claim 2 (depends on 1) The system of claim 1, wherein the first section comprises an armature. ### Claim 3 (depends on 1) The system of claim 1 wherein a location of the interface on the valve stem is selected and the LVDT position is selected to surround the interface of the valve stem when the valve stem is at a maximum linear movement position. ### Claim 4 (depends on 1) The system of claim 1, wherein the valve stem has a constant cross section along a length of the valve stem, a diameter of the constant cross section less than an inner diameter of the valve guide. ### Claim 5 (depends on 1) The system of claim 1 further comprising: a control unit coupled to the LVDT for determining an extent of linear motion of the valve stem. ### Claim 6 (depends on 5) The system of claim 5 wherein the control unit indicates whether the extent of linear motion is closer to one of a predetermined first lift height or a predetermined second lift height. ### Claim 7 (depends on 5) The system of claim 5 wherein the control unit is adapted to receive the signal from the LVDT to determine whether the rocker arm assembly is operating in a high-lift mode or a low-lift mode based on the signal. ### Claim 8 (depends on 1) The system of claim 1 further comprising: a switching rocker arm assembly 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. ### Claim 9 (depends on 1) The system of claim 1, wherein the LVDT further comprises a powered coil surrounding the central recess of the valve guide. ### Claim 10 (depends on 9) The system of claim 9, wherein the LVDT further comprises a sensor coil also surrounding the central recess of the valve guide, the sensor coil adjacent the powered coil. ### Claim 11 (depends on 10) The system of claim 10, 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. ### Claim 12 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. ### Claim 13 (depends on 12) The system of claim 12, wherein the powered coil creates an alternating magnetic field. ### Claim 14 (depends on 12) The system of claim 12, further comprising a switching rocker arm assembly adapted to drive the valve in one of a high lift mode and a low lift mode, wherein the high-lift mode causes the valve stem interface to move through a first linear distance and the low-lift mode causes the valve to move through a second linear distance smaller than the first distance. ### Claim 15 (depends on 12) The system of claim 12, wherein the powered coil, the sensor coil and the armature comprise a linear variable differential transformer (LVDT). ### Claim 16 (depends on 15) The system of claim 15, wherein the LVDT is adapted to track movement of the valve during operation of the internal combustion engine, the movement caused by a camshaft and the switching rocker arm assembly. ### Claim 17 (depends on 15) The system of claim 15, wherein the LVDT is adapted to determine whether the valve is failing to close. ### Claim 18 (depends on 12) The system of claim 12, wherein the interface comprises a portion of the first section and a portion of the second section, the portions each having a same diameter. ### Claim 19 (depends on 12) The system of claim 12, wherein at the interface, one of the first section and the second section has a diameter smaller than a diameter of the other of the first section and the second section. ### Claim 20 (depends on 12) The system of claim 12, further comprising a control unit coupled to the LVDT for determining an extent of linear motion of the first section, wherein the control unit indicates whether the extent of linear motion is closer to one of a predetermined first lift height or a predetermined second lift height. ### Claim 21 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. ### Claim 22 (depends on 21) The system of claim 21, wherein the first section comprises an armature of the LVDT. ### Claim 23 (depends on 21) The system of claim 21, wherein the interface comprises a portion of the first section and a portion of the second section, the portions each having a same diameter. ### Claim 24 (depends on 21) The system of claim 21, wherein at the interface, one of the first section and the second section has a diameter smaller than a diameter of the other of the first section and the second section. ### Claim 25 (depends on 21) The system of claim 21, further comprising a control unit coupled to the LVDT for determining an extent of linear motion of the first section, wherein the control unit indicates whether the extent of linear motion is closer to one of a predetermined first lift height or a predetermined second lift height. ### Claim 26 (depends on 25) The system of claim 25 wherein the control unit is adapted to receive the signal from the LVDT to determine whether the rocker arm assembly is operating in a high-lift mode or a low-lift mode based on the signal.