Valve Lash Setting Process

• US 20110061621A1
• Filed: 09/13/2010
• Published: 03/17/2011
• Est. Priority Date: 09/14/2009
• Status: Active Grant

• Current Assignee: Atlas Copco Industrial Technique Ab (Atlas Copco AB)
• Original Assignee: Atlas Copco Tools & Assembly Systems, LLC (Atlas Copco AB)
• Inventors: Finkenbiner, Mark Allen
• Granted Patent: US 8,646,426 B2
• Time in Patent Office: Days
• US Class Current: 123/90.45
• CPC Class Codes: F01L 1/20 Adjusting or compensating clearance

Abstract

A valve lash setting method for setting a predetermined lash in a valve assembly for internal combustion engines. The method includes generating a torque curve and using a linear regression calculation to define a zero crossing point from which a predetermined final lash position of an adjusting screw can be set and secured.

Claims

1. A method of setting valve lash for use on an internal combustion engine valve assembly having a rocker arm, a spring body, an adjuster fastener engaged with the rocker arm, and a locking fastener, the method comprising the steps of:

engaging the adjuster fastener and locking fastener with a displacement tool;

linearly displacing the adjusting fastener into contact with the spring body generating a resistance curve;

calculating a zero crossing point position of the adjuster fastener with respect to the spring body;

linearly displacing the adjuster fastener away from the spring body to a predetermined axial final valve lash position with respect to the spring body; and

securing the locking fastener to affix the axial position of the adjuster fastener with respect to the rocker arm.

2. The method of claim 1 within the step of calculating the zero crossing point further comprises the step of:

calculating a linear regression from the resistance curve.

3. The method of claim 2 wherein the step of calculating a linear regression further comprises the steps of:

recording at least two values along a substantially linear portion of the resistance curve; and

calculating a Y-intercept of the linear regression with a zero resistance baseline value to define the zero crossing point.

4. The method of claim 1 wherein the steps of linearly displacing the adjuster fastener further comprise the step of rotatably driving the adjuster fastener about an axis of rotation with a torque tool.

5. The method of claim 4 further comprising the step of:

calculating the adjusting fastener predetermined final lash position with respect to the zero crossing point.

6. The method of claim 5 wherein the step of calculating the fastener predetermined final lash position further comprises the step of calculating the corresponding angular rotational displacement of the adjuster fastener between the zero crossing point and predetermined final axial lash position.

7. The method of claim 6 wherein the step of calculating the angular rotational displacement of the adjusting fastener further comprises the step of identifying the thread pitch of the adjusting fastener.

8. The method of claim 1 further comprises step of:

measuring the backlash of the displacement tool with respect to the adjusting fastener.

9. The method of claim 1 wherein the step of tightening the locking fastener further comprises steps of:

positionally locking the adjusting fastener in place; and

independently securing the locking fastener against the rocker arm preventing axial movement of the adjusting fastener with respect to the rocker arm.

10. A method of setting valve lash for use on an internal combustion engine valve assembly with a rotary torque tool having a first rotating spindle and an independently rotating second spindle, the valve assembly having a rocker arm, a spring body, a threaded adjuster fastener engaged with the rocker arm, and a locking nut, the method comprising the steps of:

independently engaging the adjuster fastener with the tool first spindle and the locking nut with the tool second spindle;

rotating the adjusting fastener about an axis into linear contact with the valve spring body generating a torque resistance curve;

recording at least two values along a substantially linear portion of the torque curve;

calculating a linear regression using the two values along the linear portion of the torque curve;

calculating a zero crossing point position of the adjuster fastener with respect to the spring body;

rotating the adjuster fastener away from the spring body to a predetermined axial final valve lash position with respect to the spring body; and

rotating the locking nut against the rocker arm to affix the axial position of the adjuster fastener with respect to the rocker arm.

11. The method of claim 10 wherein the step of calculating the zero crossing point further comprises the step of:

calculating a Y-intercept of the linear regression with a zero torque resistance baseline value to define the zero crossing point.

12. The method of claim 10 wherein the step of rotating the adjuster fastener to a final valve lash position further comprises the steps of:

calculating a present rotational position of the fastener;

calculating the rotational displacement between the present rotational position and the zero crossing point; and

calculating the rotational displacement between the zero crossing point and the final valve lash position.

13. The method of claim 12 further comprising the step of identifying the thread pitch of the adjusting fastener to determine the axial linear movement of the adjusting fastener with respect to the angular displacement of the adjusting fastener.

14. The method of claim 10 further comprising the step of:

measuring the rotational backlash of the torque tool with respect to the adjusting fastener.

15. The method of claim 14 wherein the step of rotating the adjuster fastener to the final valve lash position further comprises the step of adding the measured backlash of the tool to the calculated rotational displacement between the present rotational position and the zero crossing point.

16. The method of claim 14 further comprising the step of tightening the locking nut against the rocker arm prior to measuring the torque tool backlash preventing axial movement of the adjusting fastener during the backlash measuring step.

17. The method of claim 10 further comprises the step of:

forcibly opening the valve assembly valve; and

closing the valve assembly valve prior to securing the adjusting fastener at the final valve lash position.

18. The method of claim 10 wherein the step of securing the locking nut to affix the adjusting fastener further comprises the step of:

locking the adjusting fastener angular and axial position with respect to the rocker arm and locking nut prior to rotating the locking nut against the rocker arm to maintain the position of the adjusting fastener at the predetermined final valve lash position.

19. A method of setting valve lash for use on an internal combustion engine valve assembly with a rotary torque tool having a first rotating spindle and an independently rotating second spindle, the valve assembly having a rocker arm, a spring body, a threaded adjuster fastener engaged with the rocker arm, and a locking nut, the method comprising the steps of:

independently engaging the adjuster fastener with the tool first spindle and the locking nut with the tool second spindle;

locking the adjusting fastener angular and axial position with the first spindle and rotating the locking nut against the rocker arm to temporarily affix the position of the adjusting fastener with respect to rocker arm;

rotating the first spindle to measure the backlash of the torque tool with respect to the adjusting fastener;

rotating the locking nut away from the rocker arm to permit rotation of the adjusting screw with respect to the rocker arm;

rotating the adjusting fastener about an axis into linear contact with the valve spring body generating a torque resistance curve;

recording at least two values along a substantially linear portion of the torque curve;

calculating a linear regression using the two values along the linear portion of the torque curve;

calculating a zero crossing point position of the adjuster fastener with respect to the spring body;

calculating a rotational position of the adjusting fastener and a first angular displacement between the present rotational position and the zero crossing point and a second angular displacement between the zero crossing point and a predetermined axial final valve lash position of the adjusting fastener;

rotating the adjuster fastener from the present position to the predetermined axial final valve lash position with respect to the spring body;

locking the adjusting fastener axial and rotational position with respect to the rocker arm with the first spindle; and

rotating the locking nut against the rocker arm to affix the axial position of the adjuster fastener with respect to the rocker arm.