Systems, methods, and devices for valve stem position sensing

Patent metadata

Field	Value
Publication number	US-10119429-B2
Application number	US-201514980870-A
Country	US
Kind code	B2
Filing date	Dec 28, 2015
Priority date	Mar 19, 2010
Publication date	Nov 6, 2018
Grant date	Nov 6, 2018

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.

First claim

What is claimed is:

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.

2. The system of claim 1 , wherein the first section comprises an armature.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. The system of claim 1 , wherein the LVDT further comprises a powered coil surrounding the central recess of the valve guide.

10. 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.

11. 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.

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.

13. The system of claim 12 , wherein the powered coil creates an alternating magnetic field.

14. 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.

15. The system of claim 12 , wherein the powered coil, the sensor coil and the armature comprise a linear variable differential transformer (LVDT).

16. 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.

17. The system of claim 15 , wherein the LVDT is adapted to determine whether the valve is failing to close.

18. 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.

19. 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.

20. 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.

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 fir

Assignees

• Eaton Corp

Inventors

• Nielsen Douglas John
• Hildebrandt Mark William

Classifications

• F01L13/0036

  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 · CPC title

• F01L2305/00

  Valve arrangements comprising rollers · CPC title

• F01L2800/18

  Testing or simulation · CPC title

• F01L1/2405 Primary

  by means of a hydraulic adjusting device located between the cylinder head and rocker arm · CPC title

• F01L1/185

  Overhead end-pivot rocking arms · CPC title