JPH0654084B2 - Method and device for adjusting tappet clearance - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a tappet clearance between an engine intake and exhaust valve and a cam, and an automated tappet clearance adjusting device used in the method. Regarding

(Prior art) To adjust the tappet clearance, generally, insert a thickness gauge of a certain thickness that matches the clearance amount between the valve stem end and the tip of the adjusting screw, and then feed the adjusting screw until it can be easily removed. Although widely used, this method has a problem that quality tends to vary due to individual differences such as the skill level of the operator.

In addition, in order to eliminate such a problem, insert a thickness gauge that is slightly larger than the clearance amount between the valve stem end and the tip of the adjustment screw to feed in the adjustment screw, and remove the air flowing out between the valve and the valve seat. The applicant has already proposed in JP-B-58-33367 about a method for adjusting the tappet clearance in which the adjusting nut is tightened at a point where the flow rate matches the flow rate of the supplied air, but the air is in the same cylinder. Since it leaks from other valves and piston rings, the clearance amount cannot be adjusted accurately by this method, and the workability is poor due to the need for a thickness gauge.

(Purpose) The present invention has been made in view of the above problems, and an object thereof is to use a thickness gauge without using a thickness gauge.
It is to propose a new method that can adjust the tappet clearance with high accuracy.

Another object of the present invention is to provide a new device capable of highly accurately and automatically adjusting the tappet clearance.

(Means for Achieving Purpose) That is, as a tappet clearance adjusting method for achieving the above object, the present invention provides a region in which the rocker arm is displaced in a state where one end of the rocker arm is in contact with the reference surface of the camshaft. First displacement set value v set in
_{The first} step of feeding the adjusting screw until reaching ₁ and the second step of feeding the adjusting screw by a fixed amount sc from this feeding position to the region where the displacement rate of the rocker arm becomes almost zero, and the rocker arm at this feeding position. a third step of returning the adjustment screw until it reaches the second displacement setting value v ₃ which is set by subtracting the set value Δv from the upper limit value v ₂ of the displacement, the feed position as the clearance adjusting origin o, the A fourth step in which the return amount Δs obtained from the set value Δv and the displacement rate of the rocker arm obtained in the first step is subtracted from the preset clearance amount, and the adjustment screw is returned by the subtracted amount. As a device to which this method is applied, means for acting on one end of the rocker arm to bring it into contact with the reference surface of the camshaft, Displacement detecting means for contacting a part of the rocker arm to detect the displacement thereof, driving means for rotating the adjusting screw by rotating it, and control means for controlling the driving means based on the detected force of the displacement detecting means. It is composed of and.

(Example) Therefore, first, a method of adjusting the tappet clearance according to the present invention will be described with reference to FIGS. 2 and 3.

As shown in FIG. 2, the rocker arm presser i presses the slipper surface e of the rocker arm a against the base surface of the camshaft d with a constant force, and under this condition, the adjusting screw b is fed by the driver j. Then, the displacement shown in FIG. 4 occurs near the adjusting screw b of the rocker arm a.

That is, when the adjusting screw b is fed in, the rocker arm a starts to change from the time point p when the tip of the adjusting screw b and the end surface of the valve stem f come into contact with each other, and this change continues to the point q and thereafter changes almost. Will not do.
That is, the apparent change of the rocker arm a from the point p to the point q is due to the play between the rocker arm a and the rocker arm shaft h, the play between the cam shaft d and its bearing, and the like. The point q indicates the point where the reaction force of the rocker arm a overcomes the load of the valve spring g and starts pushing down the valve stem f. The point that hardly changes thereafter is that the feed of the adjusting screw b is simply the valve. It is considered that this is because the spring g is merely bent and the change due to the load of the spring g is very small.

Then, the displacement amount v of the rocker arm from the point p to the point q
Has some variations depending on each rocker arm,
These increasing curves show the feed amount s of the adjusting screw b.
On the other hand, the reaction force of the rocker arm a overcomes the load of the valve spring g to start pushing down the valve stem f, that is, the region where a large displacement occurs and the displacement is almost the same. Regarding the point q located between the zero area and the point q, the feed amount of the adjusting screw b is largely different for each rocker arm, and this point q
The position of is not always clear.

A theoretical analysis of the position of this point q is shown in FIG. 4. In this case, all the parts interposed in the rocker arm are rigid, and the parts interposed in the rocker arm have constant dimensional tolerances and fits, and there is no variation.

After contacting the base surface of the camshaft d and the slipper surface e of the rocker arm a under the condition that the set load of the valve spring does not change due to torsional stress etc. even if the valve is opened and the spring is compressed. As the adjusting screw b is fed by the driver j, the rocker arm a changes in direct proportion to the adjusting screw feeding amount s from the point p where the tip of the valve stem f and the tip of the adjusting screw b contact. This is because the play caused by the fit between the rocker arm a and the rocker arm shaft h and the fit between the cam shaft d and the bearing is absorbed by feeding the adjusting screw b, and this change is the point at which the pressing of the valve starts, that is, the valve spring. The set load of g continues until the point Q where the rocker arm a is applied, and thereafter, even if the adjusting screw b is continuously fed, the rocker arm a does not change. Theoretically, this point Q should be considered as the clearance point o, and the clearance amount S should be returned from this point. However, in reality, all the parts interposed in the rocker arm a show some elastic changes, and
There is a manufacturing error within the tolerance in all the parts interposed in the rocker arm a, and when the valve spring g is compressed to a set load, the load changes due to torsional stress or the like.

Due to these synergistic effects, the straight line curves around the point Q and does not pass through the theoretical clearance point Q. Further, after the point Q, the load changes due to the torsional stress of the valve spring g and the like, so that the rocker arm slightly changes, but it is a change that can be ignored.

The present invention is based on the relationship between the feed amount of the adjusting screw b and the displacement amount v of the rocker arm a. The sole surface e of the rocker arm a is abutted against the base surface of the cam shaft d. .

Then, in a first step, the adjust b is fed until the first displacement set value v ₁ arbitrarily set between p and the point q is reached, and the displacement rate v ₁ / s ₁ of the rocker arm a is increased.
Ask for.

Then, as the second step, the feeding amount s in the first step
_The adjusting screw b is fed by a constant amount sc from ₁ to a region where the displacement rate of the rocker arm a becomes zero, and the upper limit value v ₂ of the displacement of the rocker arm a is detected at the feeding position s ₂ .

Then, as a third step, the upper limit value v _{2 of} this displacement is set.
From the second set by reducing the set value Δv to the smallest possible value
The adjusting screw b until the displacement set value v ₃ of
The feed amount s ₃ at this point is determined as the clearance adjustment origin o.

And finally, as a fourth step, the return amount Δs obtained by the set value Δv and the displacement rate v ₁ / s _{1 of} the rocker arm a obtained in the first step, that is, Δv · s ₁ / v ₁
The adjusting screw b is returned by an amount obtained by subtracting the return amount corresponding to the predetermined clearance amount s, and the tappet clearance from the true adjustment origin, that is, the point q at which the valve stem f starts to be pressed down is adjusted and set. It was done like this.

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

In the figure, reference numeral 1 is a rod 4 of a cylinder 3 fixed to a column 2.
In the driver unit housing attached to the end, a screw driver drive shaft 7 connected to a servo motor 6 via a harmonic driver 5 is attached to a rocker arm by a screw driver 9 spline-engaged at the tip via a spring 8. The sleeve shaft 10, which is attached so as to rotate the adjusting screw b of a, and which is coaxially arranged with the screw driver drive shaft 7, includes the nut runner 1 through the gears 11 and 11.
The adjusting nut c is attached so as to rotate with a socket wrench 14 which is connected to the shaft 2 through a spring 13 and is spline-engaged at its tip.

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 of the cylinder 16 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 able to move up and down by a cylinder 19 fixed to a support base 18 that is integral with the column 2, and is fixed to the rod end so that it is mounted on the head cover of the engine E. A cylinder 22 for raising and lowering a movable table 21 is attached to the displacement gauge supporting tool 20 which is lowered and fixed, and the movable table 21 is biased by a spring 23 so that its tip is a measurement point of a rocker arm a. Of the rocker arm a is detected from the displacement of the arm 22 by bringing the detection arm 24 rotatably and pivotally supported so as to abut against the reference arm of the detection arm 22 into contact with the reference surface of the detection arm 22. A displacement meter 25 that outputs a signal to the displacement display unit 26 is attached.

Reference numeral 27 in the drawing denotes a control circuit for controlling the servomotor 6 by the output signal of the displacement meter 25.

Next, the tappet clearance adjusting operation by the device configured as described above will be described.

First, the engine E from which the head cover has been removed in advance is fixed at a predetermined position, then the cylinder 21 is operated to lower the displacement meter 25, and the detection arm 24 is moved by the head.
Press.

Then, 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 cam shaft d by a constant pressing force, that is, the spring 2 for pressing the detection arm.
3. The load of about 2 kg is applied to each load of the screw driver spring 8 and the socket wrench spring 13 to press the spring.

After this setting operation, the driver unit housing 1
Is lowered by the cylinder 3, first the socket wrench 14 is brought into contact with the adjustment nut, the nut runner 12 is rotated in the forward direction, and the nut c is loosened after meshing with each other.
Then, the movable table 21 is lowered to bring the tip of the detection arm 24 into contact with the measurement point of the rocker arm a with a pressing force of about 0.5 to 1.0 kg, and further to the rocker arm displacement detection circuit of the displacement display unit 26, After the displacement set value v ₁ is set, the head of the displacement meter 25 is brought into contact with the reference surface of the detection arm 24.

Under this condition, when the servomotor 6 is normally rotated and the screw driver 9 is fed in, the displacement meter 25
Is the displacement amount v of the rocker arm a which changes momentarily from the time point p when the adjusting screw b touches the tip of the valve stem f.
Is detected and the detection output is sent to the displacement display unit 26, and when the displacement amount v of the rocker arm a reaches the _first displacement set value v ₁ arbitrarily set between the points p and 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, a constant adjusting screw feed amount sc is set in the setting circuit, and at the same time, the servo motor 6 starts operating again and the adjusting screw b is passed through the screw driver 9. Is sent by the set sending amount sc.

By the way, since the feed amount sc reaches the region where the displacement rate of the rocker arm a becomes substantially zero, the displacement amount of the rocker arm a shows a substantially constant value v ₂ at the stage when this feed is finished. become. Therefore, at this point, the value of the displacement display unit 26 is reset again, and the set value Δv that is as small as possible is subtracted from the displacement amount v ₂ to set a new second changed set value v ₃ , and the rocker arm is set. The screw driver 9 is rotated until a shows this displacement.

Then, the point indicating the second displacement set value v ₃ is set as the adjustment origin o, and while the servo motor 6 is rotationally controlled from this point, the feed to the set value Δv and the first displacement set value v ₁ is performed. The displacement rate v of the rocker arm a obtained by
₁ / s ₁ and the return amount Δs, that is, Δv ·
The return amount corresponding to s ₁ / v ₁ is subtracted from the preset clearance amount s, the adjusting screw 6 is returned, and the nut runner 12 is reversed to rotate the socket wrench 1.
Tighten the adjusting nut C with a predetermined torque according to 4.

Finally, when the unit housing 1 is raised and the rocker arm retainer 17 is subsequently raised, the detection arm 24 is rotated counterclockwise in the figure by the urging force of the retainer spring 23 and is pushed by this. Adjust screw b
Is in contact with the end of the valve stem f, and at the same time, the stroke from the clearance adjustment origin o is detected by the displacement meter 25, and this value is displayed on the displacement display unit 26 as the clearance amount. Used for judgment.

(Effect) As described above, according to the present invention, when the adjust screw is fed in a state where one end of the rocker arm is in contact with the reference surface of the camshaft, the feed amount of the adjust screw to the point where each rocker arm exists. Paying attention to the fact that the rocker arm is displaced according to a proportional relationship that is almost the same as that of the rocker arm, and after that, it is no longer displaced.First, the adjust screw is fed to the first displacement set point, and then the rocker arm is displaced by a certain amount. Since the adjustment screw is loosened to the second displacement set point from a fixed point, and finally the adjustment screw is loosened so that an appropriate tappet clearance can be obtained based on the feed amount of the adjustment screw fed by the above steps. After absorbing the characteristics peculiar to each rocker arm and the rattling and friction of the parts related to the rocker arm, It is possible to automatically adjust the tappet clearance amount based on the tendency of displacement caused by feeding the just screw, and there is no room for individual differences such as the skill level of the operator and uniform adjustment is possible. The automation can be achieved.

[Brief description of drawings]

FIG. 1 is a side view of an apparatus showing an embodiment of the present invention, FIG. 2 is a view showing a tappet clearance adjusting operation, and FIGS.
The figure is a diagram showing the feed amount of the adjusting screw and the displacement of the rocker arm. 1 ... Driver unit housing 6 ... Servo motor 9 ... Screw driver 14 ... Socket wrench 17 ... Rocker arm presser 24 ... Detection arm, 25 ... Displacement meter 26 ... Displacement display unit a ... Rocker arm b …… Adjustment screw d …… Cam shaft, e …… Sole surface f …… Valve stem

Claims (2)

[Claims] 1. Adjusting the other end of the rocker arm until _one reaches a _first displacement set value v ₁ set in a region where the rocker arm is displaced, with one end of the rocker arm being in contact with a reference surface of a camshaft. The first step of feeding the screw, the second step of feeding a certain amount sc of the adjusting screw from this feeding position to the region where the displacement rate of the rocker arm becomes almost zero, and the upper limit value of the displacement of the rocker arm at this feeding position. a third step of returning the adjustment screw from v ₂ until it reaches the second displacement setting value v ₃ which is set by subtracting a setting value Delta] v, the feed position as the clearance adjusting origin o, the set value Delta] v and the The return amount Δs obtained from the displacement rate of the rocker arm obtained in the step 1 is
A tappet clearance adjusting method comprising a fourth step of returning the adjusting screw by an amount subtracted from a preset clearance amount. 2. A rocker arm, a means for acting on one end of a rocker arm to bring the arm into contact with a reference surface of a camshaft, a displacement detecting means for contacting a part of the rocker arm to detect displacement of the arm, and a rocker arm. A tappet clearance adjusting device comprising: a driving unit that acts on an adjusting screw at the other end to drive the screw to rotate; and a control unit that controls the driving unit based on the detected force of the displacement detecting unit.