JPH0248647Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rocker arm with a built-in latch adjuster used in a valve mechanism of an internal combustion engine, and a rocker shaft that pivotally supports the rocker arm.

[Prior Art] In a valve operating mechanism in which a rocker arm is swingably supported on a rocker shaft, a cam is engaged with one end of the rocker arm to swing the rocker arm, and the other end is used to open and close a valve, temperature and wear A lash adjuster is built into the rocker arm to automatically absorb changes due to Oil is supplied to the oil chamber of the latch adjuster through an oil supply passage leading to the oil chamber from an oil hole in the rocker shaft. During operation, especially at startup, air mixed in the supplied oil is forced into the oil chamber along with the oil, and since there is no place for this air to escape, air also gets mixed into the high pressure chamber adjacent to the oil chamber via a check valve. Loss of normal function or generation of hammering sounds. As a method for removing air, a valve mechanism has been considered in which a return passage is provided from the oil chamber to the lock shaft, and the air is released from a V-groove formed on the outer periphery of the lock shaft, which is constantly in communication with the return passage (for example,
Utility Application No. 59-13348 (see Utility Model Application No. 60-124504)).

[Problems to be solved by the invention] However, in such conventional valve operating mechanisms, air bleed means such as V grooves are always in communication with the return passage, so air escapes through the air bleed means. At the same time, a large amount of oil also escapes. Since this oil returns to the oil pan without being used effectively for any other purpose, a large amount of oil escaping causes energy consumption in pumping the oil.

In order to alleviate such problems, this invention
During engine operation and startup, the air contained in the oil in the oil chamber of the latch adjuster or the oil in the oil passage is actively released to the outside, but the valve operating mechanism of an internal combustion engine limits the amount of oil that escapes. The purpose is to provide

[Means for Solving the Problems] The valve operating mechanism for an internal combustion engine of the present invention that meets this purpose has a latch adjuster slidably held in a recess formed in a rocker arm, and a latch adjuster that is slidably held in a recess formed in a rocker arm. An oil supply passage leading to the oil chamber of the adjuster is provided to supply oil to the oil chamber, and a return passage is provided leading from the top of the oil chamber to the clearance formed by the outer circumference of the rocker shaft and the inner circumference of the rocker arm. In a valve train mechanism designed to bleed air, an enlarged clearance portion is provided on the outer periphery of a camshaft and communicates with a return passage only when a rocker arm slides into contact with a cam nose of a cam.

[Operation] In the valve train of an internal combustion engine configured in this way, a certain amount of pressure is always acting on the oil chamber of the lash adjuster, and the locking arm rotates due to sliding contact with the cam nose. Only when the return passage and the enlarged clearance part on the outer periphery of the rocker shaft communicate with each other, air is blown out with oil, and when the rocker arm is in sliding contact with the base circle of the cam, the enlarged clearance part communicates with the return passage. This prevents a large amount of oil from gushing out.

Therefore, the oil is spouted intermittently, and a large amount of oil consumption is prevented.

[Embodiments] Hereinafter, preferred embodiments of the valve mechanism for an internal combustion engine of the present invention will be described with reference to the drawings.

The figure shows the vicinity of a latch adjuster of a valve train for an internal combustion engine according to an embodiment of the present invention. As shown in the figure, the rocker arm 1 is connected to the rocker shaft 2.
The latch adjuster 3 is mounted on one end.
It has a recess 4 in which it is slidably housed. The latch adjuster 3 is formed by a body 5 made of a cylindrical body with a bottom, a plunger 6 made of a cylindrical body with a bottom slidably housed inside the body 5, and a recess 4 inside the plunger 6. a high pressure chamber 8 formed between the bottom of the plunger 6 and the bottom of the body 5, and a hole 9 bored in the bottom of the plunger that communicates the oil chamber 7 and the high pressure chamber 8; A check ball 10 that is attached to the high pressure chamber 8 side of the hole 9 and allows oil to flow only from the oil chamber 7 to the high pressure chamber 8, a retainer 11 that covers the check ball 10 from below, and the retainer 11 and the check ball 10. A check ball spring 12 is interposed between the retainer 11 and the bottom surface of the body 5 and urges the check ball 10 upward, and a return spring 13 is interposed between the retainer 11 and the bottom surface of the body 5 and urges the retainer 11 upward. are doing. The upper end of the plunger 6 projects upward from the upper end of the body 5, and a notch 15 is provided at the upper end of the plunger 6 to guide oil from an oil supply passage 14 formed in the rocker arm 1 into the oil chamber 7. . The oil supply passage 14 communicates an oil passage 16 in the rocker shaft 2 with the oil chamber 7 via an oil hole 22. Reference numeral 17 denotes an upper end portion of the valve stem, which is urged upward by a valve spring 18 and is a portion that comes into contact with the lower surface of the body 5. A spacer 21 is further provided on the bottom surface 19 of the recess 4.
is applied with the outer peripheral flange portion in contact with the bottom surface 19. The flange portion of the spacer 21 has an outer diameter approximately equal to the diameter of the recess 4. The spacer 21 has an air hole 25 in the center.

The rocker arm 1 is provided with a return passage 20 that intermittently communicates the upper part of the oil chamber 7 with a clearance enlarged portion 23 formed on the outer periphery of the rocker shaft 2. The opening of the return passage 20 to the oil chamber 7 is normally provided at the center of the recess 4.
The return passage 20 is bent and extends to the upper part of the rocker shaft 2.

The enlarged clearance portion 23 is formed of a V-groove formed on the outer periphery of the rocker shaft 2. The V-groove is formed on the outer periphery of the rocker shaft to be longer in the axial direction than the fitting portion with the rocker arm 1, and both ends of the V-groove are open to the outside air. The clearance enlarged portion 23 consisting of a V-groove returns in the circumferential direction of the rocker shaft 2 only when the pad surface 1a of the rocker arm 1 comes into sliding contact with the cam nose 24a of the cam 24 and rotates, as shown in FIG. It is provided at a position communicating with the passage 20. Therefore, as shown in FIG. 1, when the pad surface 1a of the rocker arm 1 is in sliding contact with the base circle 24b of the cam 24, the clearance enlarged portion 23 is in a position where communication with the return passage 20 is cut off. be.

Next, the operation of the rocker arm of the embodiment configured as described above will be explained.

Oil supplied from the oil passage 16 in the rocker shaft 2 via the oil supply passage 14 flows into the oil chamber 7 of the latch adjuster 3. Air may be mixed in the supplied oil,
It accumulates in the upper part of the oil chamber 7 and grows. If air is mixed in when the oil in the oil chamber 7 enters the high pressure chamber 8 to compensate for the oil consumed due to leakdown, a normal valve lift may not be obtained or a knocking sound may occur. However, since the return passage 20 is formed, the air in the oil chamber 7 is intermittently vented when the return passage 20 and the enlarged clearance portion 23 communicate with each other, thereby preventing the generation of hammering sounds and the like.

In this case, the return passage 20 and the enlarged clearance part 23 are communicated with each other only when the cam nose 24a of the cam 24 comes into sliding contact with the pad surface 1a of the rocker arm 1, so the air in the oil chamber 7 and the oil passage leading thereto is , are vigorously jetted out through the return passage 20 and the clearance enlarged portion 23 together with the oil. Therefore, the air is discharged intermittently, and the risk of air entering the high pressure chamber 8 is suppressed. When the cam base circle 24b and the pad surface 1a of the rocker arm 1 are in sliding contact, communication between the return passage and the enlarged clearance portion 23 is cut off, so oil spout is suppressed and oil is always spouted as in the conventional case. Never. Therefore, oil consumption is significantly reduced.

In addition, since the clearance enlarged portion 23 is provided at the sliding portion between the outer periphery of the camshaft 2 and the inner periphery of the rocker shaft through-hole of the rocker arm 1, foreign matter does not accumulate in the sliding portion due to sliding, and air bleed is prevented. The passageway will not be blocked.

[Effect of the invention] Therefore, when using the internal combustion engine valve mechanism of the present invention, the structure is such that communication between the enlarged clearance part and the return passage is limited only when the pad surfaces of the cam nose and the rocker arm are in sliding contact. , oil consumption can be significantly reduced while maintaining the air removal effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a valve mechanism for an internal combustion engine according to an embodiment of the present invention, and FIG. 2 is a sectional view of a state in which the return passage and the enlarged clearance portion are in communication with each other in FIG. 1. 1...Rotsuka arm, 2...Rotsuka shaft,
3...Lush adjuster, 4...Recess, 6...
Plunger, 7...Oil chamber, 8...High pressure chamber, 19...
... Bottom of recess, 20 ... Return passage, 21 ... Spacer, 22 ... Oil hole, 23 ... Clearance expansion part, 24 ... Cam, 24a ... Cam nose, 2
4b...Cam base circle, 25...Air vent.

Claims (1)

[Scope of utility model registration request] The latch adjuster is slidably held in a recess formed in the locker arm, and an oil supply passage leading from the oil hole of the locker shaft to the oil chamber of the latch adjuster is provided in the locker arm to supply oil to the oil chamber. In a valve operating mechanism for an internal combustion engine, a return passage leading from the top of the chamber to a clearance formed by the outer periphery of the rocker shaft and the inner periphery of the rocker arm is provided to remove air in the oil, in which the rocker arm slides into contact with the cam nose of the cam on the outer periphery of the rocker shaft. A valve operating mechanism for an internal combustion engine, characterized in that an enlarged clearance portion is provided that communicates with the return passage only when the valve is opened.