JPH0379527B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a tappet clearance in an engine equipped with a rocker arm having an adjusting screw facing a valve stem at one end and a slipper surface facing a valve operating cam at the other end. Regarding the adjustment method.

(Prior art) Conventionally, as this type of adjustment method, the
According to Publication No. 33367, air is pressurized into the combustion chamber through the spark plug mounting hole, and a gap gauge with a thickness that adds a predetermined thickness to the tappet clearance is inserted between the valve stem and the adjustment screw. ,
In this state, tighten the adjustment screw toward the valve stem to push the valve down against the valve spring, and check whether the amount of pushing down has reached the predetermined thickness. It is known that the tappet clearance is adjusted by detecting the depth of the tappet and stopping tightening when the valve depression amount reaches the specified thickness.

(Problems to be Solved by the Invention) In the above-mentioned device, the air pressure in the combustion chamber is not necessarily constant due to air leaks from other valves and piston rings, and the clearance tends to vary, and when adjusting the clearance, the air supply pipe It is necessary to attach and detach the gauge to the plug mounting hole one by one, which makes work difficult. Furthermore, the clearance gauge is strongly pinched between the valve stem and the adjustment screw due to the downward reaction force of the valve spring, making it difficult to adjust the gauge after adjusting the clearance. There are problems in that it becomes difficult to remove the gauge and the gauge is likely to wear out.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that solves these problems and allows for accurate adjustment of tappet cleaning balance with good workability.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an engine equipped with a rocker arm having an adjustment screw facing a valve stem at one end and a slipper surface facing a valve drive cam at the other end. When adjusting the tappet clearance, first tighten the adjustment screw toward the valve stem while detecting the displacement of a predetermined detection part on one end of the rocker arm, and then tighten the adjustment screw toward the valve stem to detect the displacement of the detection part in the direction away from the valve stem. Stops tightening when the amount reaches the maximum value and no longer increases,
Next, the position of the adjusting screw at the time when the displacement reaches the maximum value or when the adjusting screw is loosened to reduce the displacement by a predetermined amount from the maximum value is set as the origin position for clearance adjustment. The adjustment screw is loosened from the original position by a predetermined amount determined in accordance with the tappet clearance.

(Operation) When the adjustment screw is tightened, its tip contacts the valve stem, and due to the reaction force of the contact, the detection part at one end of the rocker arm to which the adjustment screw is attached is displaced in the direction away from the valve stem as shown in the third figure. .

To explain this in detail, the displacement of the detection part at the time S ₀ when the slipper surface contacts the base circular part of the valve train cam and the tip of the adjustment screw contacts the valve stem is zero, and the adjustment screw is tightened. As a result, the amount of displacement of the detection part increases proportionally until the backlash of the valve mechanism, such as the clearance of the rocker arm's shaft support, is absorbed, and then the valve stem is pushed down against the valve spring. The amount of displacement reaches the maximum value L and no longer increases.

Here, the value of L varies depending on the amount of play in the valve mechanism, but the tightening position S of the adjustment screw at the point when the displacement reaches L and the valve stem starts to be pushed down, that is, point A in Figure 3. ₁ as the origin position for clearance adjustment, and then loosen the adjustment screw by a specified amount N corresponding to the desired tappet clearance amount T, the tappet clearance that is related to the amount of backlash in the valve mechanism can be adjusted. is set to T. In reality, the amount of displacement may reach L after passing through the elastic deformation region of the rocker arm (the region indicated by the dotted line in Figure 3), and it may be difficult to identify point A.
After tightening to S ₁ or more and confirming that the displacement does not increase, loosen the adjustment screw until the displacement decreases from L by the specified amount △L, and then change the adjustment screw position S ₂ . Set to the origin position.

Then, the adjustment screw is further loosened from S ₂ by a specified amount N ₁ , which corresponds to the clearance amount obtained by subtracting △L from T. According to this, the position of the adjustment screw is the same as when loosening S ₁ by N. is at position _S3 , and the tappet clearance is set to T in the same way as above.

(Example) Referring to FIG. 1, a shows a rocker arm that is mounted on the cylinder head of the engine, and an adjusting screw a1 and its fixing nut a2 are attached to one end of the rocker arm a, facing the valve stem b. At the same time, a slipper surface a3 facing the valve drive cam c is formed at the other end, and the rotation of the valve drive cam c pushes down the valve stem b through the rocker arm a against the valve spring b1. A valve mechanism is constructed, and the tappet clearance is adjusted by an adjusting device 1 disposed above the cylinder head.

The device 1 connects the rocker arm a to the slipper surface a3.
a restraining means 2 for restraining the valve drive cam c in a state in which it is in contact with the base circle portion of the valve drive cam c, a displacement detecting means 3 for detecting displacement of a predetermined detection portion a4 on one end side of the locking arm a, and a means for operating the adjustment screw a1. 4, and the restraining means 2 includes a pressing piece 2c that abuts the upper surface of the other end of the rocker arm a at the lower end of a piston rod 2b extending downward from a cylinder 2a formed in a machine frame 5 that can be freely positioned with respect to the cylinder head. The displacement detecting means 3 shall be constituted by a sensor capable of detecting the movement of the measuring element 3a at the lower end on the order of microns, and this shall be attached to a bracket 5a fixed to the machine frame 5. , a shaft 6a is attached to the lower end of the bracket 5a, as shown in FIG.
A swinging arm 6 is pivoted and is urged downward by a spring 6b with the fulcrum being a fulcrum, and a stop 6c is formed at the tip of the arm 6 to abut the detection area a4, and the measurement is performed on the corresponding stop 6c. The child 3a is abutted to detect the displacement of the detection portion a4 via the corresponding seat 6c.

The operating means 4 includes a driver 4a driven by a servo motor (not shown) and a socket 4 spline-engaged with the output shaft 4b of the nut runner.
The screwdriver 4a is inserted into the socket 4c and its tip is connected to the adjustment screw a.
1, and the socket 4c is fitted onto the fixing nut a2.

When adjusting the tappet clearance, first, by operating the cylinder 2a, the slipper surface a3 of the rocker arm a is brought into contact with the base circular portion of the valve drive cam c via the pressing piece 2c, and in this state, the driver 4a
is engaged with the adjustment screw a1, and the socket 4c is
is fitted onto the fixing nut a2, and then the socket 4c is reversed to loosen the fixing nut a2, and the detected value of the displacement detecting means 3 is reset to zero, and the screwdriver 4a is rotated forward to tighten the adjusting screw a1. onto the valve stem b side.

According to this, from the time when the tip of the adjusting screw a1 comes into contact with the valve stem b, one end side of the locker arm a is pushed upward in a direction away from the valve stem b by the contact reaction force, and the locker arm a at the detection portion a4 is pushed up. As explained in the above section, the amount of upward displacement increases as the adjustment screw is tightened.
It changes as shown in the figure, and this is detected by the displacement detection means 3.

In this case, it is actually rare to be able to identify the point A in FIG. 3 when the displacement amount reaches the maximum value L and the valve stem starts to be pushed down from the detected value of the detection means 3 due to the existence of a transient region. Therefore, in the example, the adjusting screw a1 is tightened until it is confirmed that the displacement amount no longer increases, the displacement amount at this time, that is, L is stored in the microcomputer, and then the screwdriver 4a is tightened. Reverse the rotation and loosen the adjustment screw a1 until the displacement amount becomes a value reduced by a predetermined amount △L from L. Set the position _S2 of the adjustment screw a1 at this point as the origin position for clearance adjustment, and then From _S2 onwards, the screwdriver 4a is reversely rotated by a predetermined number of revolutions corresponding to the specified amount _N1 explained in the above-mentioned operation and stopped, and then the socket 4c is rotated forward to tighten the fixing nut a2.

According to this, the adjusting screw a1 is at the position S ₁ at point A.
It is fixed at a position _S3 which is shifted to the slack side by a predetermined amount N corresponding to the desired tappet clearance amount T from the tappet clearance amount T.

Next, the driver 4a and the socket 4c are moved upward, and the pressing piece 2c is moved to the cylinder 2.
a to release the restraint of the locker arm a, and push down one end side of the locker arm a by the biasing force of the spring 6b of the swing arm 6 to bring the adjusting screw a1 into contact with the valve stem b. From the detected value of 3, the slipper surface a3 of rocker arm a
Check whether the clearance that occurs between the adjusting screw a1 and the valve stem b when the valve is brought into contact with the base circular part of the valve drive cam c, that is, △T in Fig. 3, is within the standard. Finish the adjustment work.

(Effects of the Invention) As described above, according to the present invention, the tappet clearance can be accurately adjusted based on the starting point of pressing down the valve stem, regardless of the amount of backlash in the valve mechanism, and the combustion There is no need to pressurize air into the chamber or insert or remove a clearance gauge between the adjustment screw and the valve stem, solving the above conventional problems and making it possible to adjust the clearance with high workability and high precision. It has the effect of

[Brief explanation of drawings]

Fig. 1 is a partially cutaway side view of the main parts of the device used to carry out the method of the present invention, Fig. 2 is a cutaway sectional view taken along the line - - in Fig. 1, and Fig. 3 is a diagram showing the change characteristics of the displacement amount of the rocker arm. It is. a...Lotsuka arm, a1...adjustment screw, a3
...Slipper surface, a4...Detection portion, b...Valve stem, 3...Displacement detection means, 4...Adjustment screw operating means.

Claims (1)

[Scope of Claims] 1. When adjusting the tappet clearance in an engine equipped with a rocker arm having an adjusting screw facing the valve stem at one end and a slipper surface facing the valve drive cam at the other end, first insert the adjusting screw into the rocker arm. It is tightened toward the valve stem while detecting the displacement of a predetermined detection part on one end side, and the amount of displacement of the detection part in the direction away from the valve stem reaches a maximum value and no longer increases. When the tightening is stopped, the position of the adjustment screw at the time when the displacement amount reaches the maximum value is set as the origin position for clearance adjustment, and from the origin position, the predetermined regulation according to the tappet clearance is set. A method for adjusting a tappet clearance of an engine, characterized in that the adjusting screw is loosened by a certain amount. 2. When adjusting the tappet clearance in an engine equipped with a rocker arm that has an adjusting screw facing the valve stem at one end and a slipper surface facing the valve drive cam at the other end, first insert the adjusting screw into a predetermined position on one end of the rocker arm. It tightens toward the valve stem while detecting the displacement of the detection part, and stops tightening when the amount of displacement of the detection part in the direction away from the valve stem reaches the maximum value and no longer increases. Then, the position of the adjustment screw at the time when the adjustment screw is loosened to reduce the displacement by a predetermined amount from the maximum value is set as the origin position for clearance adjustment, and the tappet clearance is adjusted from the origin position. 1. A method for adjusting a tappet clearance for an engine, characterized in that the adjusting screw is loosened by a predetermined amount according to the specified amount.