JPH0324809Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a valve train for an engine, and particularly to a type in which a hydraulic lash adjuster mechanism is built into a rocker arm.

(Prior Art) Conventionally, a plunger is slidably fitted into a cylinder formed in a rocker arm, a reservoir chamber is provided with an orifice and a check valve at the lower end, and a reservoir chamber is formed between the plunger and the reservoir chamber. A system is known that uses a hydraulic latch adjuster mechanism consisting of a high-pressure chamber and a high-pressure chamber to make the tab clearance maintenance-free and reduce noise (for example,
(Refer to Publication No. 175613).

(Problem to be solved by the invention) On the other hand, in the case where this hydraulic latch adjuster mechanism is built into the rocker arm, the rocker arm has an oil passage that guides the oil flowing in the rocker shaft to the hydraulic latch adjuster mechanism. It is necessary to provide an air bleed passage for discharging the air accumulated in the reservoir chamber and each oil supply passage in the engine when the engine is stopped into the head cover, mainly immediately after the engine is started. The method for forming both passages is to pass a passage with a diameter similar to that of an air bleed passage (a small diameter passage that is always open so it does not cause a significant drop in oil pressure) from the rocker shaft through-hole of the rocker arm to the reservoir chamber. It may be possible to create a single drill hole that opens at the top of the Rocker arm, but in this case, a relatively long distance would have to be machined using a small diameter drill, which could cause damage to the drill. This becomes a big problem and causes a problem that productivity deteriorates.

To solve this problem, as shown in the above-mentioned conventional publication, a large-diameter oil passage and a small-diameter air bleed passage are machined separately, or a single passage with a diameter larger than the air bleed passage is used. It has been proposed that a plug member provided with a diaphragm is fitted into the opening of the passageway to the upper part of the reservoir chamber.
However, in both cases, the oil passage that connects the Rotsuker shaft through-hole of the Rotsuker arm and the reservoir chamber has a much larger diameter than the air bleed passage, so the tip of the drill may deflect or bend during machining. The opening position to the reservoir chamber tends to vary, and if the variation is large, the amount of oil that accumulates in the reservoir chamber when the engine is stopped will be small, and immediately after the engine is restarted, air bleeding from the hydraulic lash adjuster mechanism will occur. There is a problem in that this causes an abnormal noise to be generated for a predetermined period of time.

The present invention has been developed in view of the above-mentioned conventional problems, and eliminates variations in the opening position of the oil passage that opens into the reservoir chamber of the hydraulic lash adjuster mechanism, thereby making it possible to reliably reduce abnormal noise when starting the engine. The purpose is to provide a highly reliable engine valve train.

(Means for Solving the Problem) In order to achieve the above object, the present invention includes a plunger slidably fitted into a cylinder formed in a rocker arm, and a reservoir chamber equipped with an orifice and a check valve at the lower end. The present invention is based on a valve operating system for an engine equipped with a hydraulic latch adjuster mechanism including a high pressure chamber formed between the plunger and a reservoir chamber. A first drill hole is drilled to extend an oil passage formed in the rocker arm from the rocker shaft through hole of the rocker arm to just before the reservoir chamber so as to guide the oil flowing inside the rocker shaft to the hydraulic latch adjuster mechanism. and a second drill hole that is drilled from the upper part of the reservoir chamber of the rocker arm, passes through the reservoir chamber, and communicates with the first drill hole, and has a smaller diameter than the first drill hole, and the first drill hole is It is assumed that it communicates with the reservoir chamber via the second drill hole.

(Effects of the invention) As described above, in the present invention, the small diameter second drill hole passes through the reservoir chamber, and the large diameter second drill hole communicates with the reservoir chamber through the first drill hole. Therefore, the second drill hole functions as an air vent passage, and since the second drill hole has a smaller diameter and is shorter than the first drill hole, it can be used in an extremely narrow specific area on the side wall of the reservoir chamber. The second drill hole can be reliably opened without any internal variation, and it is possible to prevent the occurrence of abnormal noise at the time of starting the engine due to incorrect machining of the oil passage.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. 1, 2, and 3, an engine 1 includes a cylinder block 2 having a cylinder bore 2a, a cylinder head 3 attached to the top of the cylinder block 2, and a piston 4 that moves up and down within the cylinder bore 2a. and has. A combustion chamber 5 is formed within the cylinder head 3, and an intake port 6 is formed in the cylinder head 3. An intake valve 7a is fitted into the intake port 6, and the intake valve 7 has a valve stem 7a.
It is biased in the closing direction by a spring 8 that engages with a spring retainer 7b provided at the upper end of a. A camshaft 9 is disposed at the top of the cylinder head 3, and the rotation of the camshaft 9 causes a rocker arm 1 that is swingably supported by a rocker shaft 10 to rotate.
1 to open and close the intake valve 7. Although not shown in the figure, an exhaust port is formed in the cylinder head 3, and an exhaust valve is fitted into this exhaust port, and is opened and closed by the same valve operating device as that on the intake side.

The rocker arm 11 also has a cylindrical plunger 12 with one end closed, which is slidably fitted into a cylinder 12a formed in the rocker arm 11.
b, a reservoir chamber 12e formed in the cylinder 12a and equipped with an orifice 12c and a check valve 12d at the lower end, and a high pressure chamber 12f formed between the plunger 12b and the reservoir chamber 12e. Adjuster mechanism 12
is built-in, making tab clearance maintenance-free. The rocker arm 1 is arranged to guide the oil flowing inside the rocker shaft 10 to this hydraulic latch adjuster mechanism.
The oil passage 13 formed in the rocker arm 11 has a first drill hole 13a drilled to extend from the rocker shaft through hole 14 of the rocker arm 11 to just before the reservoir chamber 12e, and has a diameter smaller than the first drill hole 13a and the oil passage 13 formed in the rocker arm 11. From the upper part 11a of the reservoir chamber 12e of the rocker arm 11 to the reservoir chamber 12
e, and a second drill hole 13b bored to communicate with the first drill hole 13a.

As described above, the small diameter second drill hole 13b passes through the reservoir chamber 12e, and the large diameter first drill hole 13a communicates with the reservoir chamber 12e via the second drill hole 13b. The second drill hole 13b has an air venting passage function, and the second drill hole 13b is connected to the first drill hole 13a.
Since the diameter is smaller and shorter than that of the oil passage 12, the amount of deflection and deflection of the drill during drilling is small, and the oil passage 13 can be reliably opened within an extremely narrow specific range of the side wall of the reservoir chamber 12e without variation. Therefore, it is possible to prevent abnormal noises caused by incorrect machining of the oil passage 13 when starting the engine. In addition, by arranging the first drill hole 13a and the second drill hole 13b constituting the oil passage 13 on the same line, the rotation stroke of the rocker arm or jig during drilling can be performed in only one stroke. Processing time can be shortened.

[Brief explanation of the drawing]

Figures 1, 2, and 3 all show an embodiment of the present invention; Figure 1 is a partial sectional view of the engine, Figure 2 is a plan view of the rocker arm, and Figure 3 is a partial sectional view of the engine. FIG. 3 is a partial cross-sectional view of the rocker arm. DESCRIPTION OF SYMBOLS 10...Rocker shaft, 11...Rocker arm, 11a...Upper part, 12...Hydraulic latch adjuster mechanism, 12a...Cylinder, 12b
...Cylindrical plunger, 12c...Orifice, 1
2d...Check valve, 12e...Reservoir chamber, 1
2f...High pressure chamber, 13...Oil passage, 13a...
...First drill hole, 13b...Second drill hole, 14
...Lotscar shaft through hole.

Claims (1)

[Claims for Utility Model Registration] A plunger slidably fitted into a cylinder formed in the rocker arm, a reservoir chamber equipped with an orifice and a check valve at the lower end, and a reservoir chamber formed between the plunger and the reservoir chamber. In a valve train for an engine equipped with a hydraulic latch adjuster mechanism consisting of a high pressure chamber and a high pressure chamber, an oil passage formed in the rocker arm is configured to guide oil flowing in the rocker shaft to the hydraulic latch adjuster mechanism. A first drill hole is drilled to extend from the rocker shaft through hole of the rocker arm to just before the reservoir chamber, and a first drill hole is drilled from the upper part of the reservoir chamber of the rocker arm to pass through the reservoir chamber and communicate with the first drill hole. A second hole with a smaller diameter than the drill hole.
A valve train for an engine, characterized in that the first drill hole is in communication with a reservoir chamber via the second drill hole.