JPH0312204B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) 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 confirmation method.

(Prior art) Conventionally, when checking the tappet clearance, a feeler gauge was inserted between the adjustment screw and the valve stem, and the operator felt the slight resistance when pulling it out to check the tappet clearance. We are trying to determine whether the amount is appropriate or not.

(Problem to be Solved by the Invention) By the way, the reason why the valve stem is pushed down against the valve spring is due to the valve mechanism, such as the clearance of the shaft support of the rocker arm, after the adjustment screw contacts the valve stem. This is when the backlash is absorbed and the contact force of the adjustment screw against the valve stem increases to a value equivalent to the valve spring load.In the end, the true value of tappet clearance is when the slipper surface is brought into contact with the valve drive cam. This value is the sum of the clearance that occurs between the adjustment screw and the valve stem when the adjustment screw is rotated, and the backlash of the valve mechanism that is absorbed when an upward force equivalent to the valve spring load is applied to the adjustment screw.

However, with the method using a feeler gauge as in the above-mentioned conventional technology, it is difficult to measure the true value of the tappet clearance, including play in the valve mechanism, and it is difficult for the operator to insert or remove the feeler gauge. This is a type of sensory test that determines whether or not the tapepet clearance is appropriate based on the resistance felt by the user.It requires a high degree of skill and is difficult to work with, so the true value of the tapepet clearance can be measured accurately and with good workability. It is desirable to be able to measure the amount of backlash in the valve mechanism. That is, if the play in the valve mechanism is too large, it will easily wear out and its durability will deteriorate, making it necessary to replace parts, and this is used as data for determining this.

An object of the present invention is to provide a method for confirming tappet clearance that meets the above requirements.

(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 the valve stem at one end and a slipper surface facing the valve drive cam at the other end. In the method of checking the tappet clearance, press the other end of the locker arm so that the slipper surface is in contact with the base circular part of the valve train cam, then release the pressure on the other end and adjust the locker arm until the adjusting screw The amount of displacement of the mounting part of the adjustment screw of the rocker arm when it is swung to a state where it contacts the valve stem, and the amount of displacement of the mounting part of the adjustment screw of the rocker arm when it is swung to a state where it is in contact with the valve stem, and the mounting part is pulled in the direction away from the valve stem by a force equivalent to the valve spring load from the oscillating state. The present invention is characterized in that the amount of displacement of the mounting portion when the mounting portion is moved is detected.

(Function) When the rocker arm is swung from the state where the slipper surface is in contact with the base circular part of the valve drive cam to the state where the adjustment screw is in contact with the valve stem, the amount of displacement of the attachment part to the adjustment screw is l ₁ Then, l ₁ is equal to the clearance created between the adjusting screw and the valve stem when the slipper surface is brought into contact with the base circular portion of the valve operating cam.

Also, if you pull up the adjustment screw mounting part from the state where the adjustment screw is in contact with the valve stem, the mounting part will
When it is pulled up by l ₁ , the slipper surface comes into contact with the base circular part, and then due to the backlash of the valve mechanism, the mounting part is further displaced upward by l ₂ , and since the pulling force is equal to the valve spring load, l ₂ is equal to the backlash of the valve mechanism that is absorbed when a lifting force equivalent to the valve spring load is applied to the adjustment screw, and thus the amount of displacement when the mounting part is pulled up.
If l ₃ (l ₃ = l ₁ + l ₂ ) is detected, this becomes the true value of the tapepet clearance, and the appropriateness of the clearance amount can be accurately determined from l ₃ .

Furthermore, by subtracting l ₁ from l ₃ , it is possible to detect l ₂ , that is, the amount of play in the valve mechanism, and it is also possible to determine whether the amount of play is appropriate.

(Embodiment) Referring to FIG. 1, a shows a rocker arm that is mounted on a cylinder head of an engine, and one end of the rocker arm a has an adjusting screw _a1 facing a valve stem b, and a fixing nut _a2 thereof. At the same time as installing the
A slipper surface _a3 facing the valve drive cam is formed at the other end, and when the valve drive cam c rotates, the valve stem b is connected to the valve spring through the rocker arm a.
Constructs an OHC type valve mechanism that pushes down against b ₁ ,
A tappet clearance adjustment device placed above the cylinder head allows adjustment of the tappet clearance and confirmation of the adjusted tappet clearance on the same stage.

The adjusting device includes a first movable frame 1 that is movable up and down in a direction substantially along the axial direction of the valve stem b, and a second movable frame 2 that is movable up and down in the vertical direction directly above the valve drive cam c. The first movable frame 1 is provided with an operating means 3 for adjusting the adjustment screw _A1 , and the second movable frame 2 is provided with a displacement detection means 4 for detecting displacement of a predetermined detection portion _A4 on one end side of the rocker arm A. is provided, and while the displacement of the detection portion _a4 is detected by the detection 4, the adjustment screw _a1 is tightened by the operating means 3 until the valve stem b is pushed down against the valve spring _b1 , and then Tappet clearance can be adjusted by loosening adjustment screw _A1 by a fixed amount.

The operating means 3 includes a driver 3a driven by a servo motor (not shown) mounted on the upper part of the first movable frame 1, and a spline engagement at the lower end of an output shaft 3b of a nut runner (not shown) on the movable frame 1. The driver 3a
is projected into the socket 3c through the output shaft 3b, and with the socket 3c engaged with the fixing nut _a2 and the driver 3a with the adjusting screw, first reverse the socket 3c and insert the fixing nut a. ₂ was loosened, then the screwdriver 3a was rotated to tighten and loosen the adjusting screw _a1 as described above, and finally the socket 3c was rotated in the normal direction to tighten the fixing nut _a2 .

The displacement detecting means 4 is constituted by a sensor capable of detecting the movement of the measuring element 4a at the lower end on the order of microns, and is attached to a bracket 2a fixed to the second movable frame 2.
A swinging arm 5 which is urged downward by a spring 5b with a shaft 5a as a fulcrum is provided at the lower end of the arm 5.
A contact seat 5c that contacts the upper surface of one end of the rocker arm a is formed at the tip of the rocker arm a, and the contact point 4a is brought into contact with the corresponding seat 5c, thus detecting the contact portion of the corresponding seat 5c with the rocker arm a at the detection point _a4. , the displacement is detected by the detection means 4, and the detected value is multiplied by the ratio of the distance between the adjustment screw a ₁ and the detection part a ₄ to the pivot point of the rocker arm a to determine the mounting part of the adjustment screw a ₁ of the rocker arm a. Measures the amount of displacement.

Further, the second movable frame 2 is provided with a pressing piece 6 that is moved up and down by a cylinder 6a formed thereon via a piston rod 6b, and when adjusting the tappet clearance described above, the pressing piece 6 moves the other end of the rocker arm a. was pressed down to keep the slipper surface _A3 in contact with the base circular portion of the valve operating cam C.

Further, the first movable frame 1 is provided with a pulling means 7 that can freely pull up the mounting part of the adjustment screw _a1 of the locker arm a in a direction away from the valve stem b.
To explain this in more detail, a tilting frame 8 that can be tilted laterally using a shaft 8a as a fulcrum is provided on the lower end bracket 1a fixed to the first movable frame 1.
A hook 9 that can be engaged with the lower surface of the attachment of the adjustment screw _A1 is inserted into the lower part of the frame 8 so as to be able to move up and down, and a piston rod 10a extending downward from a lifting cylinder 10 formed at the upper part of the tilting frame 8 is inserted into the hook 9. connected to the upper end, and the hook 9 can be freely pulled up by the cylinder 10 with a force equivalent to the valve spring load;
Further, a fixed frame 11 is attached to the bracket 1a so as to be located on the lateral side of the tilting frame 8, and a tilting cylinder 12 is attached to the fixed frame 11 for vertically moving a wedge piece 12a that contacts the lower side surface of the tilting frame 8. forming the wedge piece 12
According to the downward movement of a, the tilting frame 8 is tilted counterclockwise in the drawing against the spring 8b contracted and expanded between the tilting frame 8 and the fixed frame 11, and the hook 9 is moved as shown in the second figure. Adjustment screw _a1 is engaged with the lower surface of the mounting part, and by operating the lifting cylinder 10 in this state, the mounting part can be pulled up via the hook 9 with a force equivalent to the valve spring load. did.

Next, to explain the operation of the above embodiment, after adjusting the tappet clearance, the detection value of the displacement detecting means 4 is set to zero with the slipper surface a ₃ in contact with the valve drive cam c as described above by the pressing piece 6. After resetting, the pressing piece 6 is moved upward, and the spring 5b of the swinging arm 5 is
The biasing force is used to push down one end side of the rocker arm a to bring the adjusting screw _a1 into contact with the valve stem b, and the displacement amount of the mounting portion of the adjusting screw _a1 at this time is detected by the detecting means 4. This amount of displacement is the slipper surface a ₃
It is equal to the clearance l ₁ that occurs between the adjusting screw a ₁ and the valve stem b when the valve stem b contacts the base circular portion of the valve drive cam c.

Next, the lifting means 7 pulls up the mounting part of the adjusting screw _A1 with a force corresponding to the valve spring load as described above, and the displacement amount of the mounting part due to the pulling is calculated from the deviation of the detected value of the detection means 4 before and after pulling up. seek. As explained in the operation section above, this displacement amount is calculated by adding the clearance l ₁ to the backlash l ₂ of the valve mechanism that is absorbed when a force equivalent to the valve spring load is applied to the adjustment screw a ₁ . The value l ₃ ,
In other words, it becomes the true value of the tappet clearance, and thus the suitability of the tappet clearance amount can be accurately determined from this displacement amount _l3 .

Furthermore, by subtracting l ₁ from l ₃ , it is possible to detect l ₂ , that is, the play in the valve mechanism, and it is also possible to determine whether or not the play is appropriate.

(Effects of the Invention) As described above, according to the present invention, the true value of the tappet clearance including the backlash of the valve train can be detected accurately and with good workability without relying on the senses of the operator, and the amount of tappet clearance can be detected accurately and with good workability. In addition to being able to accurately determine the suitability of the valve mechanism, the size of the backlash in the valve mechanism can be independently detected and the suitability of the backlash can also be determined, and the confirmation work can be easily automated.

[Brief explanation of the drawing]

FIG. 1 is a cut-away side view of an example of an apparatus used for carrying out the present invention, and FIG. 2 is a cut-away side view of the main parts thereof in an operating state. a...Lotsuka arm, a ₁ ...adjustment screw, a ₃ ...
Slipper surface, b... Valve stem, b ₁ ... Valve spring, c... Valve drive cam, 4... Displacement detection means, 7... Pulling means.

Claims (1)

[Claims] 1 In a method for checking the tappet clearance of 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, the other end of the rocker arm is pressed to create a slipper. Mounting part of the adjustment screw of the locker arm when the locker arm is swung to the condition where the adjusting screw contacts the valve stem by releasing the pressure on the other end from the state where the surface is in contact with the base circular part of the valve drive cam. and the amount of displacement of the mounting portion when the mounting portion is pulled up in the direction away from the valve stem with a force corresponding to the valve spring load from the swinging state. How to check the tappet clearance.