JP2008088964A - How to adjust tappet clearance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quick and accurate tappet clearance adjustment method by determining whether or not a crankshaft rotation angle and a valve lift amount are in an appropriate relationship.
A line segment A representing an upper limit value of a tolerance and a line segment B representing a lower limit value of a tolerance are drawn in advance as a calibration curve, and the calibration line and a line segment C representing an actual measurement value are compared. In particular,
If the crankshaft rotation angle is set immediately after the valve is opened or immediately before it is closed, the valve lift amount is the smallest and the position where the valve lift amount changes. It is determined whether or not it is in the gap, and if it is in the gap or within the adjustment range, the adjustment screw is rotated by the nut runner 30 provided in the robot 3 to adjust the tappet clearance. The adjustment amount is obtained from the lift amount and the diameter and pitch of the adjustment screw.
[Selection] Figure 4

Description

  The present invention relates to a method for adjusting the tappet clearance between an engine valve stem and a rocker arm adjustment screw.

  If the clearance (tuppet clearance) between the valve stem of the engine and the adjusting screw of the rocker arm is too small, it will cause idling stability and engine stall, and if it is too large, noise will be generated. For this reason, it is necessary to accurately adjust the tappet clearance so that the above-described problems do not occur in both the cold and hot states of the engine.

  As a general tappet clearance adjustment method used in the past, an adjustment screw that is attached to the tip of the rocker arm and a thickness gauge is inserted between the valve stem, and the adjustment screw is adjusted until the thickness gauge is lightly pressed by the screwdriver. However, this method requires the skill level of the operator and may cause a human error.

  Therefore, a method disclosed in Patent Document 1 has been proposed. In this method, the adjustment screw is fed until the displacement of the rocker arm reaches a stable region, and then the adjustment screw is loosened based on the displacement detection means so as to reduce the displacement of the rocker arm by a predetermined reference amount. Is the adjustment origin, and the adjustment screw is loosened by an amount obtained by subtracting the loosening amount corresponding to the reference amount of the rocker arm from the clearance setting standard value.

JP 2001-27106 A

  There are many tappet clearance adjustment methods, not limited to Patent Document 1, but in any case, the crankshaft, driving sprocket, driven sprocket, timing chain, camshaft, rocker arm, etc. after the engine is finally assembled This does not take into account the assembly errors of the drive system parts and the accumulation of errors of individual parts.

  For this reason, even if the adjustment of the tappet clearance is completed, there is a case where the fundamental solution has not been achieved, and a further adjustment may be necessary later.

  Further, the tappet clearance adjusting method according to the present invention includes a step of incorporating at least a crankshaft, a camshaft and a valve into an engine, making the valve operable by rotating the crankshaft, and rotating the crankshaft from a starting point. The process of measuring the rotation angle of the crankshaft and the valve lift amount corresponding to this rotation angle, and whether the valve lift amount when the rotation angle from the starting point of the crankshaft is a predetermined value is within the set tolerance. And a step of adjusting an interval between the adjustment screw and the valve stem by turning an adjustment screw when the lift amount of the valve exceeds a set tolerance.

  In the present invention, it is preferable that the lift amount of the valve to be inspected is a predetermined value of the rotation angle, which is the rotation angle of the crankshaft immediately after the valve is opened or immediately before it is closed.

  The lift amount of the valve is detected, for example, by measuring the movement amount of the valve retainer with a laser displacement sensor. The means for measuring the lift amount is not limited to this, and an electromagnetic displacement detection means other than an electromagnetic induction type, a magnetic type or a laser can be used. However, since the measurement is performed after the valve is assembled, the measurement can be performed from outside the engine.

  In the present invention, if the detection result is within the set tolerance and around the set intersection, the tappet clearance or the like is adjusted as necessary, and conversely, if the set tolerance greatly deviates and exceeds the adjustment range, the engine drive system It is determined that the assembly is poor.

  According to the present invention, after the assembly of the engine is completed, the tappet clearance is adjusted after determining the relationship between the rotation angle of the crankshaft and the lift amount of the valve, and therefore occurs when many components are assembled. Even if there is an error due to the accumulation of small component errors, it can be corrected, and if it is greatly out of the set tolerance, it is possible to find a wrong assembly.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a diagram showing a part of a line to which a tappet clearance adjusting method according to the present invention is applied, FIG. 2 is a side view of an engine to which a tappet clearance adjusting method according to the present invention is applied, and FIG. 3 is a cylinder head. It is an enlarged view of the state which removed.

  An adjustment station for the tappet clearance of the assembled engine 2 is provided in the middle of the conveyance line 1 composed of a roller conveyor, and determination robots 3 are arranged on the left and right sides of the adjustment station. A laser displacement sensor 4 is attached to the determination robot 3, and the movement amount of the valve retainer is measured by the laser displacement sensor 4 to know the lift amount of the valve.

  In addition to the laser displacement sensor 4, a nut runner 30 for turning an adjustment screw is attached to the determination robot 3 when adjusting the tappet clearance. The determination robot 3 may be provided with a pulse motor that rotates the crankshaft. Further, the laser displacement sensor 4 may be fixed to another frame or the like without being attached to the robot.

  In the engine 2 to be determined, the crankcase 6 and the cylinder head 7 are assembled to the cylinder block 5, the crankshaft 8 is held between the cylinder block 5 and the crankcase 6, and the cam is interposed between the cylinder block 5 and the cylinder head 7. A shaft 9 is held, a driving sprocket 10 is attached to the crankshaft 8, and a driven sprocket 11 is attached to the camshaft 9, and a timing chain 12 is stretched between the driving sprocket 10 and the driven sprocket 11.

  In the above, when the crankshaft 8 is rotated by a pulse motor or the like, the camshaft 9 is rotated via the timing chain 12, and the rocker arm 14 whose one end is in contact with the cam 13 fixed to the camshaft 9 is connected to the shaft 15. The inlet valve 16 and the outlet valve 17 open and close about the center.

  When the valves 16 and 17 move away from the valve seat (downward movement in the figure), a gap (lift amount) is generated there. The lift amount can be known by measuring the movement amount of the valve retainer 18 by the laser displacement sensor 4 as described above.

  FIG. 4 is a graph showing the relationship between the rotation angle of the crankshaft and the lift amount of the valve. In FIG. 4, the starting point (0 °) of the rotation angle of the crankshaft is a position corresponding to the top dead center of the piston in the first cylinder of the engine to be determined.

  In the adjustment method, a line segment A that represents the upper limit value of the tolerance and a line segment B that represents the lower limit value of the tolerance are drawn in advance as a calibration curve, and the calibration curve and the line segment C representing the actual measurement value are compared. In particular, in this embodiment, the position immediately after the valve is opened or immediately before it is closed is the position at which the valve lift amount changes most when the rotation angle of the crankshaft is used as a reference. It is determined whether or not the amount is between the line segments A and B. If the amount is between or within the adjustment range, the nut runner 30 provided in the robot 3 turns the adjustment screw to turn the tappet clearance. Make adjustments. The adjustment amount is obtained from the lift amount and the diameter and pitch of the adjustment screw.

  On the other hand, if the measured value deviates greatly from the tolerance, there is a possibility of misassembly, so it is determined that the defect is bad and the cause is investigated.

The figure which shows a part of line with which the adjustment method of tappet clearance which concerns on this invention is applied. Side view of an engine to which a tappet clearance adjusting method according to the present invention is applied. Enlarged view with cylinder head removed Graph showing the relationship between crankshaft rotation angle and valve lift Diagram explaining general tappet clearance adjustment method

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Conveyance line, 2 ... Engine in assembly state, 3 ... Determination robot, 4 ... Laser displacement sensor, 5 ... Cylinder block, 6 ... Crankse, 7 ... Cylinder head, 8 ... Crankshaft, 9 ... Camshaft, 10 ... Drive Sprocket, 11 ... driven sprocket, 12 ... timing chain, 13 ... cam, 14 ... rocker arm, 15 ... rocker arm shaft, 16 ... inlet valve, 17 ... outlet valve, 18 ... valve retainer, 30 ... nut runner.

Claims (3)

At least a crankshaft, a camshaft and a valve are incorporated in the engine, and the crankshaft is rotated so that the valve can be operated. The crankshaft is rotated from the starting point and the crankshaft is rotated and the valve corresponds to this rotation angle. A step of measuring the lift amount of the valve, a step of checking whether or not the lift amount of the valve when the rotation angle from the starting point of the crankshaft is a predetermined value is within a set tolerance, and the lift amount of the valve is a set tolerance A method for adjusting the tappet clearance, the method comprising adjusting a distance between the adjustment screw and the valve stem by turning an adjustment screw. 2. The tappet clearance adjustment method according to claim 1, wherein the lift amount of the valve is measured immediately after the valve is opened or immediately before the valve is closed. 3. The tappet clearance adjusting method according to claim 1, wherein the lift amount of the valve is detected by measuring a movement amount of the valve retainer with a side length displacement sensor. How to adjust the clearance.