JPS62610A - Adjustment of tappet clearance and apparatus thereof - Google Patents

Abstract

PURPOSE:To simply and certainly adjust the tappet clearance by attaching a locker arm onto the standard surface of a cam and feeding an adjusting screw to the position where the locker arm is not turned and returning the adjusting screw by a prescribed quantity, keeping the above-described position as standard. CONSTITUTION:When the tappet clearance as valve clearance is to be adjusted, one edge of a locker arm (a) is pressed onto the standard surface of a cam (d) by a rod (i), and an adjusting screw (b) is fed within an arbitrary turning range of the locker arm (a) by a driver (j), and the screw (b) is screwed-in to the contact position with the edge of a valve stem (f), detecting the shift of the screw (b) by a shift detector (k). The screw is returned by the shift quantity of the locker arm as the lift of the cam (d), keeping the above-described position as standard, and adjustment is performed by returning the screw by a prescribed tappet clearance furthermore.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for adjusting tappet clearance between an engine intake and exhaust valve and a cam, and an automated tappet clearance adjustment device used in the method. Regarding.

(Prior technology) The general method for adjusting tappet clearance is to insert a thickness gauge with a certain thickness appropriate for the amount of clearance between the valve stem end and the tip of the adjustment screw, and then feed the adjustment screw until it easily comes out. Although widely used, this method has the problem that quality tends to vary due to individual differences in the skill level of the worker.

In addition, in order to solve this problem, a thickness gauge with a thickness that slightly increases the clearance between the valve spring and the tip of the adjustment screw is inserted, and the adjustment screw is fed in to prevent the air flowing out from between the valve and the valve seat. A patent application has already been filed in Japanese Patent Publication No. 58-33 concerning a tappet clearance adjustment method in which the adjustment nut is tightened at the point where the flow rate matches the 1i amount of supplied air.
Although it is proposed in Publication No. 387, since air leaks from other valves and piston rings in the same cylinder, the amount of clearance cannot be adjusted accurately even with this method, and a thickness gauge is required. Therefore, problems such as poor workability still remain.

(Purpose) The present invention was made in view of the above problem, and its purpose is to
The purpose of this invention is to propose a new method that can adjust tappet clearance with high precision.

Another object of the present invention is to provide a new device that can automatically adjust tappet clearance with high precision.

(Means for Achieving the Object) That is, in order to achieve the object, the present invention first sets one end of the rocker arm in contact with the reference surface of the camshaft, and then sets the first end within the range in which the rocker arm is displaced. Feed the adjustment screw forward to the displacement setting value of After returning the adjustment screw to the second displacement setting value set by
The present invention provides a tappet clearance adjustment method in which an adjustment screw is returned by an amount of tappet clearance obtained by subtracting a return amount corresponding to a displacement setting value of a displacement detecting means for contacting a part of the rocker arm to detect the displacement of the arm; a driving means for acting on the adjustment screw to rotationally drive the screw; and a control means for controlling a drive means based on a detected force.

(Example) First, the tappet clearance adjustment method according to the present invention will be explained based on the second and third examples.

As shown in Fig. 2, use the rocker arm presser to press the slipper e of the rocker arm a against the base surface of the cam shirt d with a constant force, and in this state, feed the adjustment screw b using the screwdriver j. As a result, a displacement as shown in FIG. 4 occurs in the vicinity of the adjustment screw b of the rocker arm a.

That is, as adjustment screw b is fed in, rocker arm a starts to change IJ when the tip of adjustment screw b contacts the end face of valve stem f, and this change continues up to point q and then After that, it hardly changes. In other words, the apparent change in rocker arm a from point p to point q is due to play between rocker arm a and lower car arm shaft h, play between camshaft d and its bearing, etc. Also, point q indicates the point at which the rocker arm a overcomes the load of the valve spring g and begins to push down the valve stem f, and after that it hardly changes.

This is thought to be because the feeding of the adjustment screw b simply deflects the valve spring g, and the change due to the load on the spring g is very small.

And the amount of displacement V of the rocker arm from point P to point q
Although there are some variations depending on each car arm,
These increasing curves correspond to the feeding amount S of the adjustment screw b.
On the other hand, the reaction force of the car arm a overcomes the load of the valve spring g and starts to push down the valve stem f, i.e., the area and displacement where a large displacement occurs. Regarding the point q located between the region where .

Figure 4 shows a theoretical analysis of the position of point 9. In this case, ■ All the parts intervening in the rocker arm are rigid bodies. ■ The parts intervening in the rocker arm have constant dimensional tolerances, fit, etc., and there is no variation. No ■ The set load of the valve spring is such that the base surface of the camshaft d and the slipper surface e of the rocker arm a are brought into contact under the condition that there is no load change due to torsional stress even when the valve is opened and the spring is compressed. After that, when the adjustment screw b is fed in by the driver j, the rocker arm a changes in direct proportion to the adjustment screw feed amount S from the point p where the tip of each valve stem f and the tip of the adjustment screw b come into contact. This is to absorb the play caused by the fit between the rocker arm a and the rocker arm shaft h and the fit between the camshaft d and the bearing by feeding the adjustment screw b. This change occurs at the point where the valve starts to be pushed down, that is, the valve spring. This continues until point Q where a set load of g is applied to rocker arm a, and thereafter rocker arm a will not change even if adjustment screw b is continued to be fed. Theoretically, this point Q can be considered as the clearance point O, and the clearance ls can be returned from this point. However, in reality, all the parts interposed in rocker arm a exhibit some degree of elasticity change, and
All parts interposed in the rocker arm a have manufacturing errors within tolerances, and when the valve spring g reaches a set load and is compressed, the load changes due to torsional stress and the like.

Due to these synergistic effects, the straight line curves after point Q and does not pass through point Q, which is the theoretical rearrangement point.Also, the load changes after point Q due to the torsional stress of valve spring g, etc., so this causes the rocker to The arm also changes slightly, but the change is negligible.

Based on the relationship between the feed amount S of the adjustment screw b and the displacement amount V of the rocker arm a, the present invention first brings the sole surface e of the rocker arm a into contact with the base surface of the camshaft d, and then moves from the point p. Feed the adjustment screw b until it reaches the first displacement set value Vl arbitrarily set between points q, and then continue to feed the adjustment screw b at a constant rate of 3 until the displacement of the rocker arm a becomes zero from the feed mSI. (sc Feed the feed position S
Detect the displacement v2 of rocker arm a at step 2, and further,
Adjust the adjustment screw b until the displacement set value v3 is reached by subtracting the smallest possible set value ΔV from this displacement amount v2.
is returned, the feed star S3 at this point is set as the origin for clearance adjustment 0, and finally, the adjustment screw b is returned by an amount obtained by subtracting the return amount ΔS corresponding to the set value ΔV from the predetermined clearance adjustment @S. It is.

Next, an automated device to which this tappet clearance adjustment method is applied will be explained with reference to FIG.

In the figure, reference numeral 1 indicates rod 4 of cylinder 3 fixed to column 2.
With the dryer unit (dryer unit) housing attached to the end,
Here, a screwdriver drive shaft 7 connected to a servo motor 6 via a harmonic driver 5 rotates an adjustment screw b of a rocker arm a by a screwdriver 9 whose tip is engaged with a spline via a spring 8. A sleeve shaft 10, which is attached to the screwdriver drive shaft 7 and coaxially arranged with the screwdriver drive shaft 7, is connected to a nut runner 12 via a gear 11. The adjustment nut C is attached so as to be rotated using a spline-engaged socket wrench 14.

On the other hand, a cylinder 16 is fixed to the tip of the bracket 15 protruding from the column 2, and the tip of the rod holds a rocker arm presser 17 that presses the slipper surface e of the rocker arm a against the base surface of the camshaft d with a constant pressure. I am doing it.

On the other hand, a displacement detection unit that detects the displacement of the rocker arm a is mounted so as to be movable up and down by a cylinder 19 fixed to a support base 18 integrated with the column 2, and is fixed to the end of the rod and attached to the head cover of the engine E. A cylinder 22 for raising and lowering a movable base 21 is attached to the displacement meter support 20 that is lowered and placed in place.
7-1.22 includes a detection arm 24 which is biased by a spring 23 and rotatably supported so that its tip abuts the measurement point of the rocker arm a, and a detection arm 24 which detects the head at the tip.
A displacement meter 25 is attached that detects the displacement lv of the rocker arm a from the displacement of the arm 22 by contacting the reference surface of the rocker arm a, and outputs the detection signal to the displacement display unit 26.

Note that the reference numeral 27 in the figure indicates a control circuit that controls the servo motor 6 based on the output signal of the displacement meter 25.

Next, a description will be given of the tappet clearance adjustment operation using the device constructed as described above.

First, the engine E is fixed at a predetermined position, and the displacement meter support 19 is lowered there using the cylinder 21 and is pressed and placed on the head cover.

Next, the rocker arm presser 17 is lowered, and the slipper surface e of the rocker arm a is pressed against the base surface of the camshaft d with a constant pressing force, that is, the spring 2 for the detection arm presser is applied.
3. Press with a force equal to about 2 kg added to the respective loads of the screwdriver spring 8 and the socket wrench spring 13.

After this set operation, the driver unit housing l
is lowered by the cylinder 3, first the socket wrench 4 is brought into contact with the adjusting nut, the nut runner 12 is rotated in the normal direction, and after meshing both, the nut c is loosened.
Next, the movable table 21 is lowered, and the tip of the detection arm 24 is placed at the measurement point of the rocker arm a by 0.5 to 1.0.
The head of the displacement meter 25 is brought into contact with the reference surface of the detection arm i4 after the first displacement setting value V is set in the setting circuit of the displacement display unit 26.

Under this condition, when the servo motor 6 is rotated forward and the screwdriver b is fed in, the displacement meter 25 indicates that the rocker arm changes every moment from the time p when the adjustment screw b touches the tip of the valve stem f. detect the displacement amount V of a, send the detection output to the displacement display unit 26,
At the stage when the displacement amount V of the rocker arm a reaches the first displacement setting value v1 arbitrarily set between the point p and the point q,
At the same time as resetting the setting circuit, the servo motor 6 is stopped via the control circuit 27.

When the servo motor 6 stops in this way.

Next, a fixed adjustment screw feed amount 5C is set in the setting circuit, and at the same time, the servo motor 6 starts operating again and feeds the adjustment screw b by the set feed amount sc via the socket wrench 14.

By the way, this feeding amount SC has reached a region where the rocker arm & is almost zero, so at the stage when this feeding is finished, the amount of change in the rocker arm a comes to show a substantially constant value v2. Therefore, at this point, the value of the displacement display unit ( ) 26 is reset again, and a new & setting Ml v 3 is set by subtracting the set value ΔV, which is reductively small, from this displacement amount v2, and the rocker arm a Screwdriver 9 until it shows displacement.
Rotate.

Then, the point indicating this displacement v3 is set as the adjustment origin 0, and after controlling the rotation of the servo motor and returning the adjustment screw b to the clearance adjustment setting amount S, the nut runner 12 is then reversed. Tighten the adjustment screw feed tc to a predetermined torque using the socket wrench 14.

Finally, when the unit/) housing l is raised and the rocker arm presser 17 is subsequently raised, the detection arm 24 is rotated counterclockwise in the figure by the biasing force of the presser spring 23, and is pressed by this. The adjusted screw b comes into contact with the end of the valve stem f, and at the same time the stroke from the clearance adjustment origin 0 is detected by the displacement meter 25, and this value is further displayed as the clearance amount on the displacement display 2-near 1 and 26. , this value is used for determining whether the clearance amount is acceptable or not.

(Effects) As described above, according to the present invention, when the adjustment screw is fed with one end of the rocker arm in contact with the reference surface of the camshaft, the amount of feed of the adjustment screw until the point where each rocker arm is Focusing on the fact that the rocker arm is displaced in a proportional relationship that is almost the same as that of the rocker arm, and then it stops displacing, first feed the adjustment screw to the first displacement setting point, then feed it a certain amount, and then check the displacement of the rocker arm. The adjustment screw was loosened from a constant point to the displacement setting point, and finally the adjustment screw was loosened to obtain the appropriate tappet clearance based on the amount of adjustment screw fed in in each step above. Even if there are variations in the absolute amount of displacement indicated by the arm, the tappet clearance amount can be automatically adjusted based on the displacement tendency caused by feeding the adjustment screw, regardless of this, and the operator's skill level etc. This eliminates room for individual differences and enables uniform adjustment, as well as automation.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the displacement of a side rocker arm of a device showing an embodiment of the present invention. l...Driver unit housing 6...Servo motor 9...Screw driver 14...Socket wrench 17...Rocker arm presser 24...Detection arm 25...Displacement Total 26
... Displacement display unit a ... Rocker arm b ... Adjustment screw d ... Camshaft e ... Sole surface f ...
...Valve column

Claims (1)

[Claims] 1. With one end of the rocker arm in contact with the reference surface of the camshaft, the first step is to feed the adjustment screw to a first displacement setting value set within the displacement area of the rocker arm. a second step of feeding the adjustment screw by a certain amount from this feeding position to a region where the displacement of the rocker arm becomes almost zero; A third step of returning the adjustment screw to the second displacement setting value, and a third step of returning the adjustment screw by the tappet clearance amount obtained by subtracting the return amount corresponding to the second displacement setting value in advance from this feeding position as the origin. A tappet clearance adjustment method consisting of 4 steps. 2. means acting on one end of the rocker arm to bring the arm into contact with the reference surface of the camshaft; displacement detection means contacting a portion of the rocker arm to detect displacement of the arm; and acting on the adjustment screw. A tappet clearance adjustment device comprising: a drive means for rotationally driving the screw; and a control means for controlling the drive means based on the detected force of the displacement detection means.