JP2004245111A - Valve clearance adjusting method and adjusting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically set a valve clearance in few processes with a high precision without effect of an unstable element such as backlash of an adjusting screw and oil film in a joint section between members. <P>SOLUTION: After a valve 2 is pushed in by a rocker arm 10 by a displacement exceeding the valve clearance by normally rotating the adjusting screw 12 of the rocker arm 10, the adjusting screw 12 is inverted to return the valve 2 to an original fixed position, a time when the screw is returned to the fixed position and the displacement is stopped is detected by a displacement stop detecting means 50, and a position of the rocker arm 10 at this time is recognized to be a zero position having zero clearance. Then, the adjusting screw 12 is rotated by a predetermined angle in the same inverse direction to set the valve clearance, and the adjusting screw 12 is locked by a lock nut 13 so as not to rotate. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an adjusting method and an adjusting device for automatically adjusting a valve clearance between a supply / exhaust valve of an internal combustion engine and a rocker arm for opening and closing the valve.
[0002]
[Prior art]
A predetermined gap (valve clearance) between a supply / exhaust valve urged and held by a spring material such as a coil spring in a combustion chamber of an internal combustion engine and a rocker arm that swings by a cam drive to open and close the valve. Is provided. If the valve clearance is too small, the valve cannot close normally because the thermal expansion of the valve cannot be absorbed, and if the valve clearance is too large, an abnormal sound (tappet noise) will be generated. Adjustment of the clearance is performed manually or automatically.
[0003]
Generally, the adjustment of the valve clearance is performed by manually or automatically rotating an adjusting screw screwed to a rocker arm forward or backward. When manually adjusting the valve clearance, workability is poor because multiple tools such as a flathead screwdriver that rotates the adjustment screw forward and reverse and a clearance gauge inserted between the rocker arm and the valve are required. Lack of reliability due to individual differences in adjustment accuracy. Therefore, the development of a fully automatic technology for adjusting the valve clearance has been promoted, and various automatic adjusting devices have been proposed.
[0004]
When automatically adjusting the valve clearance, the backlash of the adjustment screw screwed to the rocker arm and the idling of the driver due to the gap between the adjustment screw and the driver when rotating the adjustment screw forward and reverse with a screwdriver (bit) are problems. Therefore, it is difficult to automatically and accurately adjust the valve clearance. In addition, a simple and theoretical technique for automatically adjusting the valve clearance is as follows: from the state where the end of the rocker arm is in contact with the top of the valve and the valve clearance is recognized as zero, the adjustment screw is rotated by a predetermined angle in a predetermined direction. There is a technique for setting the valve clearance. For example, there is a device for automatically adjusting a valve clearance by swinging a rocker arm by pressing of a pressing means from the outside and setting a position of the rocker arm when the rocker arm is brought into contact with a valve to a position of zero clearance (Patent Document 1). 1).
[0005]
This automatic valve clearance adjusting device sets the final valve clearance by rotating an adjusting screw (adjustment bolt) screwed to a rocker arm that swings in conjunction with a cam in forward and reverse directions. When the rocker arm is swung in one direction from outside by a pressing means (such as a piston rod of a cylinder), the position of the rocker arm when the end of the rocker arm contacts the top of the valve without displacing the valve, It is the zero point position of zero clearance. Based on this zero point position, the adjusting screw is rotated forward and reverse to set the final valve clearance.
[0006]
[Patent Document 1]
JP 2000-73718 A (FIG. 1)
[0007]
[Problems to be solved by the invention]
In the case of an automatic adjustment device in which the clearance zero point position of the rocker arm is set by the pressing means, the zero point position is obtained by detecting the displacement amount of the rocker arm by the pressing means for pressing the rocker arm against the valve. The accuracy of the zero position of the rocker arm is not stable due to unstable factors such as the oil film between the means and the rocker arm and the fluctuation of the spring material for biasing and holding the valve. It is difficult to stabilize the clearance accuracy. Also, after the step of setting the zero point of the rocker arm by the pressing means, the adjusting screw screwed to the rocker arm is rotated forward and further reversely to obtain the final valve clearance. And it is difficult to improve work efficiency.
[0008]
An object of the present invention is to provide a valve clearance adjusting method for automatically setting a valve clearance with high accuracy with a small number of steps, while reducing the influence of unstable elements such as backlash of a rocker arm adjusting screw and an oil film. And an adjusting device.
[0009]
[Means for Solving the Problems]
The adjusting method of the present invention, which achieves the above object, comprises screwing the rocker arm 10 with a valve clearance between the valve 2 urged and held in a fixed position and a rocker arm 10 that swings back and forth to open and close the valve 2. A valve clearance adjusting method for adjusting the valve clearance by adjusting the combined adjustment screw 12, wherein the adjustment screw 12 is rotated in one direction to push the valve 2 through the rocker arm 10, and the adjustment screw 12 is rotated in the opposite direction to locker. The valve 2 is displaced via the arm 10 and a zero-point position recognizing step of recognizing a position where the displacement stops as a valve clearance zero. Setting a clearance.
[0010]
Here, when the adjustment screw 12 is rotated in one direction, the adjustment screw 12 is tightened with respect to the rocker arm 10, and the rocker arm 10 swings in one direction to push the valve 2. When the rocker arm 10 pushes the valve 2 against the urging force of the spring member for urging and holding the valve 2, the strong urging force eliminates the influence of unstable elements such as minute gaps and oil films. The rotation of the adjusting screw 12 in the reverse direction after the valve 2 is pushed in is a rotation in a direction in which the adjusting screw 12 is loosened with respect to the rocker arm 10, and this rotation causes the rocker arm 10 to swing in the opposite direction by the urging force of the valve 2. The valve 2 begins to move back to its home position. When the valve 2 is displaced to the original fixed position, the displacement stops at this fixed position. Therefore, the displacement of the valve 2 or the rocker arm 10 is detected by a linear sensor or the like. The position of the rocker arm 10 at this point is recognized as zero clearance. A simple detection circuit can be applied to the detection means for detecting only the stop point of the displacement as compared with the displacement detection means for calculating and measuring the displacement, and the detection can be performed with high accuracy. Then, by continuously loosening the adjusting screw 12 and setting the valve clearance from the time of the zero point recognition, the influence of backlash of the adjusting screw 12 and idling of the driver for rotating the adjusting screw is eliminated, and the valve is always accurately adjusted. Clearance can be set.
[0011]
Immediately after setting the valve clearance, the adjustment screw 12 is locked to the rocker arm 10 as necessary. This locking is performed by a lock nut 13 screwed to the adjustment screw 12. In this case, the locking screw 13 is rotated in the tightening direction while the adjustment screw 12 immediately after setting the valve clearance is prevented from rotating in the tightening direction by a screwdriver or the like.
[0012]
In addition, the adjusting device of the present invention for achieving the above object provides a valve clearance between the valve 2 urged and held at a fixed position and the rocker arm 10 which reciprocates and swings to open and close the valve 2. A screw rotating means 20 for rotating the adjusting screw 12 forward and backward, and a nut for rotating the locking nut 13 screwed to the adjusting screw 12 forward and reverse. A rotating means, a brake means for temporarily applying a brake to the rotation of the adjusting screw, and a displacement stop detecting means for detecting a time point at which the valve displaced by the swing of the rocker arm stops; It is characterized.
[0013]
Immediately after the adjusting screw 12 is loosened by the screw rotating means 20 to set the valve clearance, the brake means 40 applies a brake to the screw rotating means 20 to prevent the adjusting screw 12 from rotating in the tightening direction. . In this state, when the lock nut 13 is rotated in a direction to be tightened by the nut rotating means 30 and the adjustment screw 12 is locked to the rocker arm 10, the adjustment screw 2 turns in the same direction as the lock nut 13, that is, the so-called co-rotation is reliably prevented. As a result, the once set valve clearance does not fluctuate, and the valve clearance adjustment accuracy is stabilized.
[0014]
Further, the displacement stop detection means 50 only needs to detect the displacement stop when the displacement of the valve 2 or the displacement member which is displaced integrally with the valve 2 is temporarily stopped, and a simple circuit configuration can be applied. The displacement stop detecting means 50 is in contact with a displacement member such as a valve retainer 3 which is connected to the valve 2 and is displaced integrally with the valve 2, and a displacement rod 52 which is displaced in accordance with the displacement member; A displacement detecting means 51 for continuously detecting the displacement of 52 is provided, and a time point at which the displacement signal from the displacement detecting means 51 is temporarily stopped is detected.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0016]
1 to 3 show an OHV type valve operating mechanism in which a rocker arm 10 is cam-driven via a push rod 7, and the rocker arm 10 swings about a substantially central shaft 11 to supply and exhaust air. Valve 2 is opened and closed. Although two valves 2 are shown as a pair on the left and right in the drawing, one valve may be basically used. The valve 2 is biased and held by the spring material 4 on the cylinder block 1. A spring member 4 of a compression coil spring is inserted between the valve retainer 3 fixed to the upper end of the valve 2 and the cylinder block 1, and the lower end of the valve 2 closes the supply / exhaust port by the urging force of the spring 4, The valve 2 is urged and held at a closed position at a predetermined height. The valve retainers 3 of the pair of left and right valves 2 are connected to the bridge member 5, and a desired valve clearance is set between the top of the bridge member 5 and the valve-side end 10 b of the rocker arm 10.
[0017]
When one valve 2 is used, the bridge member is omitted, and a desired valve clearance is set between the valve retainer 3 at the upper end of the single valve 2 and the valve side end 10b of the rocker arm 10. Is done.
[0018]
An adjusting screw 12 is screwed into the cam-side end 10a of the rocker arm 10, and a lock nut 13 is screwed into the adjusting screw 12. A minus groove 12 a is formed at the upper end of the adjusting screw 12, and the lower end of the adjusting screw 12 is engaged with the upper end of the push rod 7. The lower end of the push rod 7 engages with the cam 6. When the cam 6 rotates, the push rod 7 moves up and down, the rocker arm 10 swings back and forth, and the valve 2 opens and closes. FIGS. 1 to 3 show a state in which the push rod 7 is engaged with the outer circumference of the perfect circle of the cam 6 and the valve 2 is urged and held at the closed position.
[0019]
The device for automatically adjusting the valve clearance of the valve operating mechanism includes the screw rotating means 20, the nut rotating means 30, the brake means 40, and the displacement stop detecting means 50.
[0020]
The screw rotating means 20 inserts the bit 21 of the tip of a flathead screwdriver into the slot 12a of the adjusting screw 12 to rotate the adjusting screw 12 forward and reverse. For example, when the adjusting screw 12 is rotated forward by the bit 21 The adjustment screw 12 is moved to be fastened to the end 10a of the rocker arm 10 to swing the rocker arm 10 clockwise in FIG. When the adjustment screw 12 is reversed by the bit 21, the rocker arm 10 swings counterclockwise by the urging force of the spring member 4. The forward rotation and the reverse rotation of the bit 21 are performed via a servomotor 22 and a speed reducer 23. A brake means 40 is detachably connected to a rotating portion (not shown) of the servomotor 22, and the rotation of the bit 21 is appropriately braked.
[0021]
The nut rotating means 30 is a cylindrical body which is removably fitted to the lock nut 13, and the screw rotating means 20 is inserted through the cylindrical body. The lower end of the nut rotating means 30 is fitted to the lock nut 13, and the upper end is engaged with the drive gear 31. The drive gear 31 is connected to a rotation shaft of a drive motor 32. The drive motor 32 drives the drive gear 31 and the nut rotation means 30 forward and reverse. Each of the nut rotating means 30 and the screw rotating means 20 is supported by, for example, a movable frame 33 which moves up and down, and each of the nut rotating means 30 and the screw rotating means 20 independently moves up and down with respect to the movable frame 33 to rotate. Drive.
[0022]
The displacement stop detecting means 50 detects when the displacement of the valve 2 during the adjustment of the valve clearance temporarily stops. 1 to 3, the displacement of the bridge member 5, which is a displacement member that is displaced together with the pair of left and right valves 2 by swinging of the rocker arm 10, is continuously detected by a displacement detection unit 51 such as a linear sensor. The displacement stop detecting means 50 detects when the displacement detection of the detecting means 51 stops, and outputs control signals to the screw rotating means 20 and the nut rotating means 30 as described later. The displacement detection means 51 extends the displacement rod 52 so as to extend and contract downward, and the lower end of the displacement rod 52 abuts on the bridge member 5. When the rocker arm 10 swings, the displacement rod 52 moves up and down in accordance with the up and down movement of the bridge member 5, and the displacement of the displacement rod 52 is continuously detected by the displacement detecting means 51, and the detected displacement signal is output. It is output to the displacement stop detecting means 50.
[0023]
When only one valve 2 is provided, the displacement rod 52 abuts on a valve retainer 3 which is a displacement member fixed to the upper end of one valve 2 and displaced together with the valve 2 as shown by a chain line in FIG. Then, the displacement of the displacement rod 52 may be continuously detected by the displacement detecting means 51, and the detected displacement signal may be output to the displacement stop detecting means 50.
[0024]
Next, the adjustment method of the present invention using the valve clearance adjusting device will be described with reference to the front views at the time of each operation in FIGS. 1 to 3 and the graph showing the outline of the adjustment screw displacement-time relationship in FIG. Will be explained.
[0025]
As shown in FIG. 1, in a state where the valve 2 is biased and held at a predetermined closed position, the bit 21 of the screw rotating means 20 is inserted into the minus groove 12 a of the adjusting screw 12, and the nut rotating means is inserted into the lock nut 13. The displacement rod 52 of the displacement detecting means 51 is brought into contact with the valve-side end 10b of the rocker arm 10.
[0026]
When the preparation for the valve clearance adjustment described above is completed, first, the nut rotating means 30 is slightly rotated to the left to reverse the lock nut 13, and the lock nut 13 is loosened with respect to the rocker arm 10. Is rotatable. Thereafter, the screw rotating means 20 is rotated clockwise to rotate the adjusting screw 12 forward in the direction of tightening the rocker arm 10, and the rocker arm 10 is swung clockwise in FIG. By this swing, the valve side end portion 10b pushes the bridge member 5 downward, and pushes down the valve 2 in the closed position. When the lower end of the valve 2 is pushed down by the rocker arm 10 by a displacement amount (about 0.5 mm) exceeding the valve clearance as shown by the chain line in FIG. 1, the forward rotation of the screw rotating means 20 is stopped. At this time, the spring member 4 is compressed, and the influence of an unstable element such as an oil film between the rocker arm 10 and the bridge member 5 and a minute gap of another movable portion is eliminated by the reaction force of the strong urging force.
[0027]
When the adjusting screw 12 is normally rotated by the bit 21 of the screw rotating means 20, the bit 21 slightly rotates in the minus groove 12a of the adjusting screw 12 as shown in step S1 of FIG. Engages with the inner wall surface of the minus groove 12a to rotate the adjusting screw 12 forward. The idling of the bit 21 at this time does not affect the displacement when the valve 2 is pushed down. Then, after the normal rotation of the adjusting screw 12 is stopped in step S2 in FIG. 4, the bit 21 is rotated in the reverse direction and slightly idle, and then both ends of the bit 21 are engaged with the minus grooves 12a as shown in step S3. Then, the loosening operation by the reverse rotation of the adjusting screw 12 is started. During the loosening operation of the adjusting screw 12 caused by the reverse rotation, as described later, the zero position of the zero clearance of the rocker arm 10 is recognized, and the valve clearance is subsequently set. Is performed, and all the steps of the valve clearance adjustment are completed.
[0028]
When the adjustment screw 12 is loosened by the reverse rotation of the bit 21 in step S3, the rocker arm 10 starts swinging counterclockwise by the urging force of the spring material 4, and the valve 2 is displaced in the ascending direction. start. The displacement of the valve 2 is continuously detected by the displacement detecting means 51 via the bridge member 5. Then, when the valve 2 is displaced to the original closed position, as shown in FIG. 2, the lower end of the valve 2 comes into contact with the supply / exhaust port of the cylinder block 1 and the displacement of the valve 2 stops. The displacement stop detecting means 50 detects the moment of the displacement stop, and recognizes that the rocker arm 10 is at the position where the valve clearance is zero based on the detection signal. When the zero point position is recognized in step S4, the bit 21 during the reverse rotation operation remains engaged with the minus groove 12a. Therefore, the zero point recognition can always be performed with stable accuracy without the influence of the idling of the bit 21 and the backlash of the adjusting screw 12.
[0029]
When the zero point position of the rocker arm 10 is recognized, the bit 21 is subsequently reversed from step S5 to continue the operation of loosening the adjusting screw 12. The reverse rotation of the bit 21 is performed from step S5 by the rotation angle corresponding to the desired valve clearance, and the rotation of the bit 21 is stopped in step S6. Then, as shown in FIG. 3, the rocker arm 10 swings counterclockwise according to the rotation angle of the bit 21 from step S5 to step S6, and a predetermined valve clearance is set. This setting of the valve clearance has a high precision of the zero point position of the rocker arm 10 and continuously reverses the adjusting screw 12 by a predetermined angle without the bit 21 idling in the minus groove 12a. Be executed.
[0030]
In step S6, the reverse rotation of the bit 21 stops, and the temporary valve clearance setting ends. Here, it is possible to lock the adjustment screw 12 to the rocker arm 10 so that it cannot be rotated, by rotating the nut rotating means 30 forward and tightening the lock nut 13. When the loosening of the adjusting screw 12 is completed in step S6, the brake means 40 is operated to apply a brake to the rotation of the bit 21, and as shown in step S6 of FIG. 4, the bit 21 is inserted into the minus groove 12a. Hold it engaged. Thereafter, the nut rotating means 30 is rotated forward to tighten the lock nut 13, and the adjusting screw 12 is locked to the rocker arm 10 so as not to rotate. When the lock nut 13 is rotated forward, the bit 21 is engaged with the minus groove 12a of the adjustment screw 12 so as to prevent the adjustment screw 12 from rotating forward, as shown in step S7 of FIG. The adjustment screw 12 does not rotate along with the lock nut 13 that rotates forward, and there is no possibility that the once set valve clearance fluctuates.
[0031]
The present invention is not limited to the valve clearance adjusting device of the OHV type valve operating mechanism, and is applied to, for example, a valve clearance adjusting device in an OHC type or DOHC type valve operating mechanism in which a rocker arm is directly swung by a cam. It is also possible.
[0032]
【The invention's effect】
According to the present invention, the adjustment screw of the rocker arm is rotated in one direction to tighten it, the rocker arm is swung in one direction to push the valve in a fixed position, and then the adjustment screw is rotated in the opposite direction to loosen. The rocker arm recognizes that the clearance is zero when the valve starts displacing to the original home position and stops moving after reaching the original home position. The valve can always be stably output without being affected by the backlash of screws and screws, and the final valve clearance can be set with high accuracy. Also, by simply turning the adjusting screw of the rocker arm in one direction and then rotating in two steps in the opposite direction, a series of valve clearances can be set, so that the valve clearance can be adjusted with high efficiency by reducing the number of steps. .
[0033]
Further, the displacement stop detecting means for detecting the displacement stop of the valve has an advantage that a simple and inexpensive detection circuit can be applied as compared with a displacement amount detecting means which calculates and measures a series of displacement amounts of the valve. .
[0034]
Also, after adjusting the valve clearance by loosening the adjusting screw with the screw rotating means and preventing the adjusting screw from rotating in the direction in which the adjusting screw is tightened by the braking means, the adjusting screw is locked with the lock nut when the adjusting screw is locked by the lock nut. It is possible to provide a highly reliable valve clearance adjustment device in which the once-set valve clearance is stabilized and the valve clearance is once set.
[Brief description of the drawings]
FIG. 1 is a front view of a main part showing an embodiment of a valve clearance adjusting device according to the present invention.
FIG. 2 is a front view of the adjusting device of FIG. 1 when a zero point position is recognized.
FIG. 3 is a front view of the adjusting device of FIG. 1 when a valve clearance is set.
4 is a graph showing an adjustment screw displacement amount-time at the time of adjusting the valve clearance of the adjustment device of FIG. 1;
[Explanation of symbols]
1 Cylinder block 2 Valve 3 Displacement member (valve retainer)
5 Displacement member (bridge member)
Reference Signs List 6 Cam 7 Push rod 10 Rocker arm 12 Adjusting screw 12a Slotted groove 13 Lock nut 20 Screw rotating means 21 Bit 22 Servo motor 23 Reducer 30 Nut rotating means 31 Drive gear 32 Drive motor 33 Movable frame 40 Brake means 50 Displacement stop detecting means 51 displacement detection means 52 displacement rod

Claims (4)

A valve clearance adjusting method for adjusting a valve clearance between a valve biased and held at a fixed position and a rocker arm that reciprocates and swings to open and close the valve with an adjusting screw screwed into the rocker arm,
Rotating the adjusting screw in one direction and pushing the valve through the rocker arm;
Rotating the adjusting screw in the opposite direction to displace the valve via the rocker arm, a zero point position recognition step of recognizing a position where the displacement stops as zero clearance,
Rotating the adjusting screw by the predetermined angle in the reverse direction from the time of the zero point recognition to set the valve clearance. A valve clearance adjustment method that adjusts the valve clearance between the valve biased and held in place and the rocker arm that reciprocates and swings to open and close the valve with an adjustment screw with a lock nut screwed into the rocker arm So,
Rotating the adjusting screw in one direction and pushing the valve through the rocker arm;
Rotating the adjusting screw in the opposite direction to displace the valve via the rocker arm, a zero point position recognition step of recognizing a position where the displacement stops as zero clearance,
A step of setting the valve clearance by rotating the adjustment screw by the predetermined angle in the opposite direction from the time of the zero point recognition,
Rotating the lock nut screwed to the adjustment screw in the same one direction in a state where the adjustment screw is prevented from rotating in one direction, and tightening the lock nut to the rocker arm to lock the adjustment screw to the rocker arm. To adjust the valve clearance. A device that adjusts a valve clearance between a valve biased and held at a fixed position and a rocker arm that reciprocates and swings to open and close the valve with an adjusting screw with a lock nut screwed into the rocker arm,
Screw rotating means for rotating the adjusting screw in the normal and reverse directions, nut rotating means for rotating the lock nut in the normal and reverse directions screwed to the adjusting screw, brake means for temporarily applying a brake to the rotation of the adjusting screw, and a rocker arm A displacement stop detecting means for detecting a time point at which the valve displaced by the swing of the valve stops. The displacement stop detecting means includes a displacement rod that is connected to the valve and that contacts the displacement member that is displaced integrally with the valve, and that is displaced in accordance with the displacement member, and a displacement that continuously detects the displacement of the displacement rod. The valve clearance adjusting device according to claim 3, further comprising a detecting unit.

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