JPS6319683B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tappet gap adjustment for an internal combustion engine, and more particularly to an adjustment device for adjusting the tappet clearance in an internal combustion engine assembly process.

Conventionally, the tappet gap adjustment described above requires a high level of skill and effort, since it is determined whether the tappet is acceptable or not based on the feel of the gap gauge at the time of extraction, and this cannot be done in a factory that mass-produces automobile engines or the like.

Therefore, an automatic tappet gap adjustment device that does not use a gap gauge was proposed, as described in Japanese Utility Model Publication No. 52-36885, but the tappet adjustment screw is tightened to the tip of the valve stem with a preset low torque, and the clearance ( Since this is used as the reference point (zero point) for adjusting the tappet gap, torque management is a problem due to the valve closing spring, and the friction of the rocker arm,
There are many unstable factors such as play in the tappet adjustment screw. JP-A No. 52-1999, which takes into account these unstable factors,
It is disclosed in Publication No. 124519.

On the other hand, as disclosed in Japanese Unexamined Patent Publication No. 52-73213, the present applicant has managed the above-mentioned clearance adjustment reference point with the gap between the valve and the valve seat formed by screwing in the tappet adjustment screw. We have proposed a method to eliminate the unstable factors and set the tapepet clearance extremely accurately. The outline of its composition is as follows.

The combustion chamber 2 of the engine 1 (see Figure 1) is sealed by closing the exhaust valve 3 and the intake valve (not shown), the pipe cap 5 is screwed into the spark plug mounting hole 4 airtight, and the fluid pressure source 6 is sealed. A fluid (for example, air) at a constant pressure P is introduced into the closed combustion chamber 2 through the throttle 9, and the fluid pressure in the chamber is set to P.

Screw in the tappet gap adjustment screw 7 of the valve 3 for which the tappet gap is to be set (the example is the exhaust valve 3, but the same applies to the air supply valve), push down the valve stem 31 against the valve closing spring 34, and then set the valve stem 31. When the opening 32 (FIG. 2) is opened, the air in the combustion chamber 2 leaks to the exhaust passage 33, and the air pressure in the combustion chamber 2 decreases in correlation with the amount of leakage, and the amount of leakage and the fluid pressure source 6 At the point when the amount of replenishment from The pressures P and P' are indicated by pressure gauges 10 and 11 connected to respective pipes 12 and 13 on both sides of the constriction 9 of the pipe connecting the constant pressure air source 6 and the mouthpiece 5.

Now, set a gap gauge with a thickness equal to the sum of the valve closing stroke α (for example, 0.25 mm) by the valve closing spring 34 and the predetermined tappet gap T (for example, 0.1 mm) + T (for example, 0.35 mm) between the adjusting screw 7 and the stem 31. When the pressure inside the combustion chamber based on the fluid leak for that thickness reaches the reference value P' set in advance on the pressure gauge 11, screwing in the adjusting screw 7 is stopped and the feeler gauge is removed. is the valve closing spring 34
Return by stroke α and close, tapepet gap T
is formed.

In addition, instead of reading the above-mentioned pressures P and P' with the pressure gauges 10 and 11, they are detected with pressure sensors 141 and 141', and converted into currents with current exchangers 142 and 142'. Current detector・A/
The specification of the earlier application discloses that the leak detection device 14 can be digitally displayed using a D converter or the like.

By using the above method, the machining dimensions of each part will vary.
Accuracy of the adjusting screw 7 and locker arm female thread, play and friction between the locker arm 22 and its swing shaft 22',
This method is less affected by the deflection of the valve closing spring 34 and allows for highly accurate and stable adjustment, but there is a problem with automation because it uses a feeler gauge.

The present invention improves this and enables complete automation, and the gist of the invention is as set forth in the claims.

The structure and function of the illustrated example will be explained below. In the assembly process, the valve 3 is closed by the spring 34, the adjusting screw 7 is separated from the stem 31 as shown in FIG. 2, and the lock nut 20 is also in the locked position. It shall be located higher up.

The drive motor 8 rotates forward in response to the start command, and the shaft 8
1. Screw in the adjustment screw 7 using the screwdriver 82 and push down the stem 31 and valve 3 as shown in FIG. In response to the above command, the leak detection device 14 also starts operating at the same time, and air enters the combustion chamber 2 from the fluid pressure source 6 and reaches a pressure P.

Leak detection device 1 detects the drop pressure value P' (leak amount) when valve 3 is pushed in and a gap corresponding to the valve closing stroke α is created between the valve seat and the valve seat.
4, and that set point is used as the clearance adjustment reference point (zero point). When the leak detection device 14 detects that the reference point has been reached, the pressure value P' is converted into an electrical signal and sent to the electrical control device 15. When the electric control device 15 receives the above electric signal, it sends a signal to a motor control circuit 16 such as an encoder to return the adjusting screw 7 by a distance corresponding to the sum of the above-mentioned valve closing stroke α and a preset tappet gap T. The control circuit 16 converts the normal rotation of the adjusting screw drive motor 8 to reverse rotation according to the command.

Therefore, the valve 3 initially has a closing spring 34
Using this point as a reference point, the adjusting screw 7 is unscrewed by the sum of α and the tappet gap T (α + T), and a predetermined tappet gap is established between the valve stem 31 and the valve stem 31. T is obtained (Fig. 2, 3).

When the above operation is completed, the control device 15 sends a signal to the circuit 18 that controls the lockite drive motor 17, causes the locknut 20 to contact the locker arm 22 with the locknut turner 19, and tightens to the allowable torque by the torque detection circuit 21 (the first 2
4), a tightening end signal is sent from the circuit 21 to the electric control device 15 to complete one cycle.

The above leak detection device 14/electrical control device 1
5. Well-known techniques are applied to the motor control circuits 16 and 18, the torque detection circuit 21, etc. Stem 31'
The same procedure is applied to the side air supply valve.

As described above, the present invention uses the state in which the valve has been pushed down by the valve closing stroke α by the valve closing spring 34 as a reference point, and forms the tappet gap T by returning the adjustment screw by α+T from that point. Because of this, it can be automated without the need for a feeler gauge.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the apparatus of the present invention, and FIG. 2 is an explanatory diagram of the tappet gap adjustment sequence. 1 is an internal combustion engine, 2 is a combustion chamber, 3 is an exhaust valve,
4 is a spark plug mounting hole, 6 is a constant pressure fluid source,
7 is a tappet adjustment screw, 8 is a motor for driving the adjustment screw, 14 is a leak detection device, 15 is an electric control device, 16 is a motor control circuit, 17 is a lock nut drive motor, and 18 is the motor control circuit.

Claims (1)

[Claims] 1. Means for feeding fluid at a constant pressure p from the spark plug mounting hole 4 into the closed combustion chamber 2 with the supply/exhaust valve 3 closed through a restriction, and a method for setting a tappet gap. A motor 8 drives the tappet gap adjustment screw 7 to push down the valve 3 and leak fluid at pressure P in the combustion chamber, and fluid leakage occurs when the valve 3 opens by an amount corresponding to the valve closing stroke α by the valve closing spring 34. A leak detection device 14 detects the pressure drop value P' in the combustion chamber due to the pressure drop value P', uses this as a clearance setting reference point, and exchanges the above electrical signal from the leak detection device 14 to an electrical signal indicating that the reference point has been reached. Then adjust the adjusting screw 7 to adjust the valve closing stroke α.
an electric control device 15 that generates an electric signal to return the screw by a distance (α+T) corresponding to the sum of the tappet gap T and a predetermined tappet gap T; A tappet gap adjusting device for an internal combustion engine, comprising: a motor control circuit 16 which unscrews the adjusting screw 7 by (α+T) from the set reference point to form a tappet gap T.