JPS627364B2 - - Google Patents

Description

Detailed Description of the Invention This invention improves the gap between the rocker arm and the valve in a valve mechanism such as an overhead camshaft OHC system or an overhead valve OHV system that opens and closes the intake and exhaust valves of an internal combustion engine. This invention relates to a tappet gap adjustment device that adjusts to an appropriate value, and its purpose is to always adjust accurately and quickly regardless of valve stem installation errors.

The intake and exhaust valves generally installed in internal combustion engines are
It is opened and closed at appropriate timing by a valve mechanism using cams, rocker arms, etc., and there are various types of mounting structures. For example, when an overhead camshaft OHC type valve operating mechanism is shown in Fig. 1, 1 is a cam, 2 is a rocker arm, 3 is a valve, and 4 is a cylinder head. The cam 1 is fitted onto a cam shaft 5 and rotates, and is always in contact with the rear end of the rocker arm 2. The locker arm 2 swings around a fulcrum 6, and has an adjustment screw 7 screw-fitted to its tip, and a lock nut 8 is fastened to the top of the adjustment screw 7, thereby allowing adjustment of the adjustment screw 7. This prevents the screws from coming loose later. The lower end of the adjusting screw 7 is in a position to push the head of the valve 3, and the swinging movement of the rocker arm 2 pushes the valve 3 down against the valve spring 9 to open it.

By the way, in the valve train, a cam 1 is installed on the rocker arm 2 in order to absorb the thermal expansion errors of various parts such as the valve 3 and cylinder head 4 due to the rise in engine temperature and to reliably close the valve 3.
A small gap is provided between the lower end of the adjusting screw 7 and the head of the valve 3 when the valve 3 is completely closed and no upward force is applied. This gap TP
This is the so-called tappet gap, which is adjusted using the adjustment screw 7. If this becomes too small, the airtightness inside the cylinder will deteriorate, causing a reduction in engine output, backfire (intake side), afterfire (exhaust side), etc. If it is too large, there are problems such as causing tappet noise, so it is necessary to always adjust the tappet gap to an appropriate value. Conventionally, the tappet gap TP can be adjusted by inserting a feeler gauge (not shown) between the head of the valve 3 and the lower end of the adjusting screw 7, and manually inserting the adjusting screw 7 into the feeler gauge using a screwdriver. The tappet gap was adjusted by tightening them so that they were in contact. If this is the case, it will be very difficult to work because it is a manual adjustment.
At the same time, since it relies on the delicate sense of the operator's hands, variations occur and it is difficult to make constant adjustments. Therefore, an adjustment device was proposed that automatically adjusts the tapepet gap TP. This is shown in Fig. 2. Numeral 10 is a socket fitted into the upper part of the adjusting screw 7, numeral 11 is a pulse motor that rotates the socket 10 in forward and reverse directions, and numeral 12 is a valve spring that is integrally attached to the head of the valve 3. A contactor 14 is a detection means such as a differential transformer that detects and stores the amount of displacement of the valve 3 via the contactor 12, and connects the spindle 15 to the contactor 12. It is brought into contact with the contactor 12 and is interlocked with the contactor 12. To adjust the tappet gap, rotate the pulse motor 11 and use the socket 10 to rotate the adjustment screw 7 in the forward direction so that it comes into contact with the head of the valve 3, then rotate it further in the forward direction to push down the valve 3 by a certain amount, and then By rotating the adjustment screw 7 in the opposite direction, the adjustment screw 7 is detected by the detection means 14.
and valve 3 return to the detection position at the time of first contact,
From this position, the adjusting screw 7 is further returned to a predetermined rotation angle that provides a proper tappet gap, and at this position, the lock nut 8 is tightened, fixed, and adjusted. This would have made it possible to automate the adjustment, but since the displacement of the valve 3 would be detected, there would be a problem in that adjustment errors would occur. That is, the valve stem 3a and the valve guide (not shown) provided in the cylinder.
Usually 0.06 between
A gap of ~0.09 mm is provided, and due to this gap, when the adjustment screw 7 comes into contact with the valve head, the valve stem 3a tilts, and the spring seat 13 integrated therewith also tilts. As a result valve 3
An error will occur between the displacement of the spring seat 13 and the displacement of the spring seat 13 detected by the detection means via the contactor 12, and the adjustment screw 7 is adjusted based on the displacement having this error. There was a drawback that the tappet gap was uneven.

In view of the above-mentioned drawbacks of the conventional art, the present invention has been developed to improve and eliminate the drawbacks by detecting the amount of displacement of the rocker arm and automatically adjusting the tappet gap based on this. The structure of the present invention will be described below with reference to embodiments shown in the drawings.

In FIG. 3, A is a rotation control unit that tightens and loosens the adjustment screw 7 and lock nut 8 attached to the rocker arm 2 by rotating them forward and backward, and B is a rotation control unit that detects and stores the displacement position of the rocker arm 2. C is a detection unit for controlling the tightening/loosening timing of the adjustment screw 7 in the rotation control unit A, and C is a swing control unit that swings the rocker arm 2 independently of the cam 1. placed on top. The adjustment head 20 is guided by a slide 21 and moved up and down by a cylinder 22 above the tappet adjustment position.
A stopper 23 is provided at the lower end of the slide 21 to stop the adjusting head 20 at a fixed position. Reference numeral 24 in the rotation control section A is a lock nut socket rotatably supported within the bracket 25 via bearings 26a and 26b, and the lock nut 8 is tightened by fitting the lower opening into the lock nut 8. , are connected to a small motor 29 via gears 27 and 28. Reference numeral 30 denotes a driver shaft which is rotatably supported within the lock nut socket 24 via bearings 31a and 31b.The lower end of the driver shaft is fitted into the minus groove of the head of the adjustment screw 7, and the adjustment screw 7 is rotated in forward and reverse directions. A worm wheel 32 is fixed to the upper end, and a worm 35 connected to a pulse motor 34 via a coupling ring 33 is meshed with the worm wheel 32.

Further, the detection section B is composed of a measuring element 36, a displacement meter 37, etc., and this measuring element 36 is pivotably attached to the lower end of a slide 38, and is always counterclockwise by a spring 39 compressed between the two. The tip of the rocker arm 2 receives rotational force in the direction, and its tip contacts the bottom surface of the rocker arm 2. The rear end is used to measure the displacement of a magnet scale, photoelectric displacement meter, differential transformer, potentiometer, etc. installed on the top of the slide 38. Total of 37 spindles 3
The position of the rocker arm 2 is detected by the displacement meter 37 via the measuring element 36, and this is stored in the memory element. Slide 38
is slidably disposed within the guide body 40 of the adjustment head 20, and is slid laterally by the cylinder 41. When not adjusted, it is retracted to the left, and when adjusted, the adjustment head 20 is at the lower end. When it comes, the slide 38 is advanced to the right, and the tip of the probe 36 is brought into contact with the lower surface of the rocker arm 2. Also, 4 of the swing control section C
Reference numeral 2 denotes a swinging cylinder provided in the adjustment head 20, which swings the rocker arm 2 separately from the cam 1 during tappet adjustment.A pressing piece 43 is swingably pivoted to the lower end of the piston rod 42a. A spring 45 is compressed and interposed between the pressing piece 43 and the receiving piece 44 fixed to the lower part of the piston rod 42a to apply a rotational force in the counterclockwise direction to the pressing piece 43 to provide play. cylinder 42
When the piston rod 42a and the pressing piece 43 descend to press the rocker arm 2, the fluid is supplied to the b port 46b of the rocker arm 2. When the piston rod 42a and the pressing piece 43 descend to press the rocker arm 2, the rocker arm 2 is prevented from being pressed by more than a predetermined amount, and in the pressed state, the rocker arm 2 is raised by other external force. I have done it so that I can get it. Further, the elastic force of the spring 45 is set to be smaller than the elastic force of the valve spring 9 to prevent the valve 3 from being pushed open.

To explain how to adjust the tappet in the above configuration, first, place the engine that requires adjustment in a predetermined position below the adjustment head 20 using a suitable conveyance means, operate the cylinder 22, and move the adjustment head 20 onto the slide 21. along the same line until it abuts against the stopper 23. During this lowering, the small motor 29 and pulse motor 34 are used to rotate the lock nut socket 24 and the driver shaft 30 at low speed and in the reverse direction, and at the same time as the lowering, the lock nut socket 24 is set to lock nut 8, and the driver shaft 30 is adjusted. Fit it into the head of screw 7. Also, when descending, fluid is supplied to the b port 46b of the swing cylinder 42, and the piston rod 42a and the pressing piece 4
3 to press the rocker arm 2 and move the slide 38 backward, and after the adjustment head 20 has finished lowering, move the slide 38 forward with the cylinder 41 so that the tip of the probe 36 touches the bottom surface of the tip of the rocker arm 2. Let them come into contact with you. Before adjustment, the adjusting screw 7 is loosened so as to generate a sufficient tappet gap TP, and the locking nut 8 is kept in a state in which the adjusting screw 7 is not locked.

In this state, the small motor 29 and pulse motor 3
4 and adjust the tappet gap. That is, fluid is supplied to the a port 46a of the swing cylinder 42 to raise the piston rod 42a and the pressing piece 43, thereby releasing the pressing force on the rocker arm 2. Then, the probe 36, which is biased by the rotational force of the spring 39, swings and pushes up the tip of the rocker arm 2 until its rear end contacts the base circle of the cam 1, and the head of the valve stem 3a and the adjustment screw 7
Generate a sufficiently large tappet gap _TP1 between the The displacement position of the rocker arm 2 at this time is measured by the displacement meter 37 via the measuring element 36 and stored. Let this stored value be _C1 . Next, fluid is supplied to the b port 46b of the swing cylinder 42, the piston rod 42a and the pressing piece 43 are lowered, and the tip of the pressing piece 43 is pressed and swung on the rocker arm 2, so that the tip of the adjusting screw 7 is fixed to the valve 3. the head of the person. That is, the tappet gap becomes zero. The displacement position of the rocker arm 2 at this time is also detected by the displacement meter 37 and stored. Let this stored value be _C2 . Then, in this state where the tappet gap is zero, the pulse motor 34 is operated, the driver shaft 30 is rotated forward via the worm 35 and the worm wheel 32, the adjusting screw 7 is tightened, and the rocker arm 2 is raised. The measuring stylus 36 indicates that the displacement position of the rocker arm 2 has reached the appropriate position C ₃ determined from the above two memorized values C ₁ and C ₂ .
When detected by the displacement meter 37 via the displacement meter 37, the pulse motor 34 is stopped and the rotation of the adjustment screw 7 is stopped. At this point, the proper tappet gap TP is set. Next, the small motor 29 is operated, and the lock nut socket 2 is connected via the gears 28 and 27.
4 in the forward direction, thereby tightening the lock nut 8 and fixing the adjustment screw 7, the tappet adjustment is completed. When the lock nut 8 rotates, the adjustment screw 7 tries to rotate together, but the driver shaft 30 is locked by the worm wheel 32 and the worm 35, so the adjustment screw 7 does not rotate together and does not cause positional deviation. Thereafter, the adjustment head 20 is raised by operating the cylinder 22 and removed from the engine to complete the work. Incidentally, if the cylinder 47 is provided so that there is no gap between the driver shaft 30 and the adjustment screw 7 during adjustment, and the driver shaft 30 is pressed by this cylinder 47, the adjustment will be made more reliable.

The proper position _C3 of the rocker arm 2 in the above-mentioned adjustment process can be determined by a simple calculation, and thereby an appropriate tappet gap can be obtained. That is, the tappet gap is arbitrarily set in advance by taking the difference between the memorized values C ₁ and C ₂ detected at the upper and lower limits of the rocker arm 2's swing range in which the valve 3 is not opened or closed.
TP ₁ is determined (C ₂ −C ₁ =TP ₁ ). Since this tappet gap TP ₁ is set to a value sufficiently larger than the proper tappet gap TP, by finding the difference between the two, the extra gap, that is, the corrected value X can be obtained (TP ₁ -TP=X). Therefore, it is only necessary to protrude the adjustment screw 7 by this correction value X. When the adjustment screw 7 is made to protrude by the correction value
will be displaced by an amount equivalent to the correction value X. Therefore, the position where the Rocker arm 2 is displaced by the correction value X from the adjustment start point _C2 becomes the proper position _C3 . By calculating and storing this proper position _C3 by the displacement meter 37, a proper tappet gap TP can be obtained. This relationship is shown in a graph as shown in FIG. In the figure, the broken line represents the displacement of the rocker arm 2.

In this way, by detecting the displacement position of the rocker arm 2 and adjusting the tappet gap by setting a correction value based on this, it is possible to always perform stable and highly accurate adjustment without causing adjustment errors due to the inclination of the valve 3, etc. I can do it.

In the above explanation, the case where the application is applied to an OHC type valve mechanism has been explained, but the present invention is not limited to this, and the present invention is also applicable to an OHV type (overhead valve type),
It can be similarly applied to valve mechanisms such as the DOHC system (overhead multiple camshaft system) or the SV system (side valve system).

As explained above, the present invention includes an adjustment head that can approach and separate from the cylinder head, and a driver shaft that can freely engage the adjustment screw of the rocker arm and that is rotationally driven by a pulse motor via a worm mechanism. , a rotation control unit is provided on the adjustment head, the rotation control unit being able to freely engage with the lock nut of the adjustment screw and concentrically supporting a lock nut socket that is rotatably driven by a small motor independently of the driver shaft; , a rocker arm is provided with a rocking control unit capable of pressing and releasing the pressure on the valve stem head;
The amount of displacement of the tip of the Rocker arm when the rocker arm is pressed against the valve stem head by the rocking control unit and when the pressure is released is detected through the measuring element that contacts the lower surface of the tip of the Rocker arm, and the amount of displacement of the Rocker arm tip is determined to be the normal tappet gap amount. Since a detection unit is provided that calculates the difference between the two and drives the driver shaft via the pulse motor based on the calculation result, the adjustment head is brought close to the rocker arm, and the rocker arm is first controlled by the rocker arm by the swing control unit. By pressing the stem head only once and then releasing the pressure, the detection unit determines the amount of displacement of the rocker arm during this time, that is, the tappet clearance before adjustment, and compares this with the normal tappet clearance. It is possible to determine the difference between the two and accurately turn the adjustment screw by this difference using a pulse motor to set the regular tappet gap.

In particular, the adjustment screw only needs to be rotated by the difference between the initial gap amount and the regular tapepet gap amount in the adjustment direction, which reduces the hassle of tightening using constant torque control, etc., and the time required to set the zero point of the detector. No effort is required at all, and the tappet gap can be adjusted continuously and efficiently.

In other words, the detection section automatically calculates the initial gap amount by pressing and releasing the pressure on the swing control section, and also calculates the difference from the regular tappet gap amount, and based on this, the pulse motor adjusts the adjustment screw as described above. It is extremely rational because only the difference can be adjusted accurately, there is no waste, and the time required for adjustment can be shortened compared to the conventional method.

Furthermore, since the driver shaft was driven via a worm mechanism, when the lock nut was tightened, the worm mechanism's worm locking action caused
The brake is applied automatically, and there is no need for a special brake device, which has the advantage of simplifying the device.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main parts of a general OHC type valve mechanism, Fig. 2 is a sectional view of a conventional automatic adjustment device, and Fig. 3 is a side view of a tappet adjustment device according to the present invention. , FIG. 4 is a graph showing the displacement position of the rocker arm. A... Rotation control section, B... Detection section, C... Rocking control section, 2... Rocker arm, 7... Adjustment screw, 8... Lock nut.

Claims (1)

[Claims] 1. An adjustment head that can move toward and away from the cylinder head, a driver shaft that can freely engage an adjustment screw of a rocker arm and that is rotationally driven by a pulse motor via a worm mechanism, and a lock nut of the adjustment screw. A rotation control unit is provided that concentrically supports a lock nut socket that can be freely engaged and rotated independently of the driver shaft by a small motor, and a locker arm is connected to the valve stem head in the adjustment head. A swing control section capable of pressing and releasing the pressure is provided in the adjustment head, and the adjustment head is configured to control when the swing control section presses the valve stem head of the rocker arm via a measuring element that contacts the bottom surface of the tip of the rocker arm. A detection unit is provided which detects the amount of displacement of the tip of the rocker arm when it is released, calculates the difference from the regular tappet gap amount, and drives the driver shaft via the pulse motor based on the calculation result. Features a tapepet gap adjustment device.