JPH01138306A - Valve system of engine - Google Patents

Abstract

PURPOSE:To effectively remove air bubbles in oil by interposing a bearing on the way of an oil supplying passage to a lash adjustor, and oil inlet of the bearing to the lash adjustor on a portion where oil film pressure is generated. CONSTITUTION:The bearing 20a of a cam shaft is provided on the upper surface of a cylinder head 1. An oil supplying passage 21 is arranged at the downward of the bearing 20a, while an upper end of a branch passage 22 extending therefrom is opened as an oil supplying port 23 to the peripheral surface of the bearing 20a. An oil supplying passage 14 to a lash adjustor 10 is arranged parallelly to the oil supplying passage 21, while the upper end of an oil passage 26 extending from an oil supplying passage 25 communicating with the oil supplying passage 14 is opened as an oil inlet 27 on the peripheral surface of the bearing 20a. The oil inlet 27 is formed on a portion of the bearing 20a, where an oil film pressure is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve train for an engine equipped with a hydraulic lash adjuster, and more particularly to an improvement in an oil supply passage to the lash adjuster.

(Prior art) Conventionally, engine valve mechanisms have been designed to automatically adjust valve lash to zero in order to reduce noise and make equipment easier by eliminating the need for valve lash adjustment work. It is known that a hydraulic lash adjuster is incorporated.

By the way, this hydraulic lash adjuster was first developed in 1986.
As disclosed in Japanese Patent No. 1-152707, oil in an oil pan of an engine is fed by an oil pump to an oil supply passage formed in a cylinder head,
The oil is fed from the oil supply port of this oil supply passage through an oil inlet provided on the packet peripheral wall of the hydraulic lash adjuster.

However, the oil in the oil pan contains many air bubbles, so if oil containing air bubbles was supplied directly to the hydraulic lash adjuster, it would cause noise generation and deterioration of driving performance at high speeds. . Therefore, it has been proposed to provide a filter for removing air bubbles in the middle of the oil supply passage, but it has been difficult to remove air bubbles using the filter.

(Object of the Invention) Therefore, an object of the present invention is to provide an engine valve operating system that can effectively remove air bubbles in oil supplied to a hydraulic lash adjuster.

(Structure of the Invention) The present invention provides a bearing section for a rotating shaft such as a camshaft or a balance shaft driven by an output shaft of an engine in the middle of an oil supply passage for a hydraulic lash adjuster, and also It is characterized in that the oil intake port to the lash adjuster is set at a portion of the bearing portion where oil Di is generated.

(Effects of the Invention) According to the present invention, the oil that is force-fed to the lash adjuster through the oil supply passage is once captured and released into the atmosphere at the bearing portion, thereby reducing the amount of oil contained in the oil. air bubbles are removed. Since the oil inlet to the lash adjuster is set at the part of this bearing that generates hydraulic pressure, oil from which air bubbles have been removed can be supplied to the lash adjuster using the hydraulic pressure generated in this bearing. . Therefore, it is possible to prevent noise and improve the function of the lash adjuster, and it is possible to increase the high speed rotation limit of the engine.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a valve train mechanism equipped with a hydraulic lash adjuster 10.
D is configured to push down the pulp 12 with D as a fulcrum.
It has an OHC configuration.

That is, the cylinder head 1 is formed with an intake port 3 and an exhaust port (the exhaust port is not shown) that open into the combustion chamber 2, and the intake port 3 is equipped with a pulp 12 that opens and closes it. The pulp 12 is urged upward, which is the valve closing direction, by the pulp spring 4. Also, on the cylinder head l is a camshaft 5.
is rotatably supported, and a cam 6 is attached to this camshaft 5. A shaft 7 is fixed to the center of the swing arm 11, and a roller 8 that contacts the cam 6 is rotatably fitted onto the shaft 7 via a needle bearing 9. Each lash adjuster 10
has an accommodation hole 1 for accommodating this lash adjuster 10.
Oil is supplied from an oil supply passage 14 opened in the wall surface of 3. Since the lash adjuster 10 itself is well known, a detailed explanation of the structure and operation of the lash adjuster 10 will be omitted, but 15 is a plunger and 16 is a check ball. Further, 17 is a cam cap that rotatably supports the camshaft 5, 18 is a pulp sleeve, and 19 is a spring retainer.

Next, FIG. 2 shows a plan view of the cylinder head 1 with the lash adjuster 10 attached thereto, and FIG. 3 shows a front view of its upper part. A plurality of them are arranged in two rows along the cylinder arrangement direction of the engine. An oil supply passage 21 is provided below each of these bearings 20 and extends in the cylinder arrangement direction over almost the entire length of the cylinder head l, and from these oil supply passages 21 a branch passage 2 is provided.
2 extends upward, and the upper end of the branch passage 22 opens into the circumferential surface of each bearing part 20 as an oil supply hole 23 for the bearing part 20. The two oil supply passages 21 have oil in the oil pan that is pumped by the oil pump into the cylinder through an oil intake port 24 provided at the rear end (the upper end in FIG. 2) of the oil supply passage 21. It is supplied from the block side to lubricate each bearing part 20.

The oil supply passages 14 described above for supplying oil to the lash adjuster 10 are provided parallel to and inside the oil supply passage 21, and these oil supply passages 14 are connected to the cylinder head 1. It communicates with an oil passage 25 extending horizontally below the bearing portion 20a at the front end (lower end as seen in FIG. 2). An oil passage 26 is formed that extends obliquely upward from this oil passage 25, and the upper end of the oil passage 26 is opened on the circumferential surface of the bearing portion 20a as an oil intake port 27 for the lash adjuster 10.

FIG. 4 is an explanatory diagram showing the state of the camshaft 5 being supported in the bearing part 20a, and the actual clearance value between the camshaft 5 and the bearing part 20a ranges from a minimum of several microns to a maximum of 50 microns.
It is on the order of microns (shown exaggerated in Figure 4). In that case, if the rotational direction of the camshaft 5 is clockwise in FIG. 4, an oil film having a pressure distribution with a maximum downward pressure as shown by symbol A in the third quadrant is generated.

The present invention supplies oil to the lash adjuster 10 using the hydraulic pressure generated in the bearing portion 2Qa. In this embodiment, the oil intake port 27 for the lash adjuster 10 is connected to the pressure of the oil well film. A portion of distribution A where the oil pressure is not very high, that is, θ=306
-60', and oil is supplied to the lash adjuster 10 by the hydraulic pressure of this part. The reason why the oil intake port 27 is set in the range of θ = 306 to 60'' is that oil pressure is insufficient in areas where θ is smaller than this range, while oil pressure is insufficient in areas with high oil pressure where θ is greater than the above range. Hydraulic pressure is released from the intake port 27 and the bearing part 2
This is because it has a significant effect on oil film formation at 0a.

In this way, by interposing the bearing portion of the camshaft 5 in the middle of the oil supply passage to the lash adjuster 10, the oil supply passage 21 is connected to the lash adjuster 10 by the oil pump.
The oil pumped through the bearing part 20a is once released to the atmosphere while it rotates about 3/4 of a revolution together with the camshaft 5 in the bearing part 20a. Therefore, air bubbles contained in the oil are effectively removed here. Then, the oil from which air bubbles have been removed is transferred from the oil intake port 27 to the oil passage 26, 25 and the oil supply passage 1 by the hydraulic pressure generated in the bearing portion 20a.
Since the liquid is supplied to the lash adjuster 10 through the lash adjuster 10, noise can be prevented and the function of the lash adjuster 10 can be improved.

Incidentally, in this embodiment, the oil intake port 27 for the lash adjuster 10 is provided in the frontmost bearing portion 20a closest to the driven portion of the camshaft 5 for the following reason. That is, the oil pressure distribution in the bearing portion of the camshaft 5 is affected by bending vibration of the camshaft 5 and the like. However, in a general engine, a pulley is attached to the front end of the camshaft 5, and the camshaft 5 is driven by the engine output shaft via a belt mounted on this pulley. is pressed against the frontmost bearing 20a closest to the driven part by the tension of the belt, and therefore this bearing 20a is pressed against the camshaft 5.
This is the part that is least susceptible to the effects of bending vibration, and it is also the part that generates the highest hydraulic pressure. Therefore, the high oil R1 pressure as shown in FIG. 4 can always be obtained in a stable state.

In this embodiment, in order to remove air bubbles in the oil supplied to the lash adjuster 10, the bearing part 20a of the camshaft 5 is selected as the bearing part to be interposed in the oil supply passage to the lash adjuster 10. However, the present invention is not limited to this, and it is also possible to provide the above-mentioned bubble removal function and oil pumping function to the bearing part of another rotating shaft driven by the engine output shaft, such as a balance shaft. It's good.

Furthermore, the present invention is applicable not only to a valve train using the lash adjuster 10 and the swing arm 11 (but also to a valve train in which the lash adjuster is directly interposed between a cam and a valve).

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing a valve train for an engine according to the present invention, Fig. 2 is a plan view of the cylinder head, Fig. 3 is a front view showing the main parts thereof, and Fig. 4 is an oil at the bearing section. FIG. 2 is an explanatory diagram showing the pressure distribution. 1-Cylinder head 5-Camshaft 10-Lash adjuster 11-Swing arm 12-Valve 13--Lash adjuster housing hole 14.21--Oil supply passage 15-Plunger 16--Check ball

Claims (1)

[Claims] 1. In a valve train for an engine equipped with a hydraulic lash adjuster, a bearing portion for a rotating shaft driven by the engine output shaft is interposed in the middle of an oil supply passage for the lash adjuster, and A valve operating system for an engine, characterized in that an oil intake port for the lash adjuster in the bearing portion is set at a portion of the bearing portion that generates oil film pressure. 2. A bearing part interposed in the oil supply passage to the lash adjuster and provided with an oil intake port to the lash adjuster is selected from among the plurality of bearing parts of the camshaft driven by the engine output shaft. 2. The valve train for an engine according to claim 1, wherein the bearing portion is the closest to the driven portion of the shaft.