JPS63295810A - Sealed type rush adjustor - Google Patents

Abstract

PURPOSE:To improve the durability of a diaphragm by using the working oil for a rush adjustor which is not compatible with the mineral oil group or synthetic oil group engine oil. CONSTITUTION:In the sealed type hydraulic rush adjustor A in the valve system of an internal combustion engine, a gap between a body 7 and a valve stem 4 is reduced to zero by transferring the working oil sealed inside, and the error due to thermal expansion can be automatically corrected. Since the working oil is sealed by a pressure chamber 9, supply chamber 15, and a rubber diaphragm 16, and the engine oil is compulsorily supplied into the slidable part between a body guide 6 and the body 7, the engine oil and the working oil always contact through the diaphragm 16. When the working oil which is not compatible with the engine oil is used, the intrusion of the engine oil into the working oil through a diaphragm film is prevented, and the increase of the working oil exceeding the absorption capacity of the diaphragm is prevented, and durability can be improved markedly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a sealed lash adjuster for automobiles.

[Conventional technology]

The operating mechanism of the sealed hydraulic lash adjuster, which has been widely used in automobiles, is as follows. For example, as shown in FIG. 1, the rocker arm 3 supported by the arm support shaft 2 is rotated by the rotation of the camshaft 1, and the rocker arm 3 pushes down the pulp stem 4 to produce pulp (
In a valve mechanism in which the pulp stem (not shown) is opened and the pulp is closed by the pulp spring 5 fitted on the outside of the pulp stem 4, a sealed lash adjuster A is installed between the rocker arm 3 and the pulp stem 4. This eliminates gaps, automatically corrects errors caused by thermal expansion, suppresses noise, and enables accurate pulp control. Therefore, the sealed lash adjuster A has a body 7 slidably inserted inside a cylindrical body guide 6, a plunger 8 installed inside the body 7, and a plunger 8 placed between the closed end of the body 7 on the lower surface of the plunger 8. A pressure chamber 9 is formed, and a spring 10 housed in the pressure chamber 9 pushes down the body 7 and pushes up the plunger 8, so that the rod 1 on the upper surface of the plunger 8
1 is brought into contact with a protrusion 12 provided at the closed end of the body guide 6. Further, an axial passage 13 is formed in the plunger 8, and a check valve 14 is attached to the end of the passage 13 that opens at the pressure chamber S, and a supply chamber 15 is connected to the pressure chamber 9 through the passage 13. The upper part is sealed with a diaphragm 16, and the supply chamber 15 and pressure chamber S are filled with hydraulic oil. In the diaphragm 16, the upper end of the inner cylindrical part is attached to the upper part of the rod 11, and the upper end of the outer cylindrical part is attached to the upper part of the inner peripheral surface of the body 7, so that when the body 7 pushes down the valve stem 4, The hydraulic oil sealed in the pressure chamber S is compressed, and a part of it leaks into the supply chamber 15 from the gap between the sliding part between the body 7 and the plunger 8, and the hydraulic lash adjuster A is moved upward by the rotation of the Ronca arm 3. When the valve stem 4 moves to a position where a gap begins to appear between the lower end surface of the body 7 and the upper end surface of the valve stem 4, the body 7 moves downward due to the elasticity of the spring 10, thereby lowering the pressure inside the pressure chamber S. , the check valve 14 opens the passage 13, and the hydraulic oil in the supply chamber 15 leaks from the passage 13 to the pressure chamber S. As described above, the amount of oil in the supply chamber 15 changes due to the movement of the body 7 in the axial direction, and the volume of the hydraulic oil changes due to changes in temperature. It must be flexible enough to absorb moisture, and when it is incorporated into an automobile internal combustion engine, the temperature can reach 170'C, which is extremely high temperature for a rubber material. It must also have excellent heat resistance.

In this way, sealed lash adjusters, which are necessary to improve automobile engine performance, have strict usage conditions.
Usable hydraulic oil and diaphragm materials are extremely limited. The hydraulic fluid used in some conventional systems is silicone-based, and the diaphragm is made of carefully selected fluorosilicone rubber. However, even in such a combination, there is a problem in terms of durability (life span). When the engine oil comes into contact with the hydraulic oil through the rubber film, it penetrates into the hydraulic oil, increasing the amount of hydraulic oil and impairing the function of the lash adjuster.

[Problems to be Solved by the Invention] As described above, in the conventional technology, even if the hydraulic oil and diaphragm of the sealed lash adjuster are carefully selected and combined in terms of quality, the engine oil does not work through the rubber membrane. When it comes into contact with oil, it unilaterally infiltrates into the hydraulic oil, causing a significant increase in the amount of hydraulic oil, which exceeds the absorption capacity of the diaphragm (impairing the function of the lash adjuster) and reducing durability.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention employs a method of using a hydraulic oil that is substantially incompatible with mineral oil-based or synthetic engine oil in a sealed lash adjuster. The details will be described below.

Taking the sealed lash adjuster A shown in FIG. 1 as an example, hydraulic oil is sealed by a pressure chamber 9, a supply chamber 15, and a rubber diaphragm 16, and engine oil is used to lubricate the body guide 6 and body 7. Since the oil is forcibly supplied to the sliding parts by the oil pump, engine oil and hydraulic oil are always in contact with each other via the diaphragm 16. Automotive engine oils are generally labeled according to the viscosity and performance classification set by the SAE in the United States, but currently, multigrade oils labeled as 10W-30 dominate, and the viscosity (at 100°C) ) is in the range of 9.3 to 12.5 cSt, and the low temperature properties are considered to be equivalent to IOW grade. Considering the viscosity-temperature characteristics, a lubricating oil that is substantially incompatible with such or similar engine oils is a barflow polyethyl oil, preferably one having the following repeating structure 1) -←C, F, - 0→r 2) −+C, Fz, −0−h−(−C, F=y−0
-H (where X and y are both integers of 1 to 4, n and m are integers that vary depending on the viscosity) is a perfluoropolyether oil having a main chain, and this is used as a hydraulic oil. This is because, in addition to being substantially incompatible with engine oil, the properties required of the hydraulic oil in this invention include excellent viscosity-temperature characteristics (high Vl) as a lubricating oil, heat resistance, and cold resistance. However, it is not easy to have all of these properties (for example,
Even if silicone oil is incompatible with engine oil at room temperature, the compatibility increases at around 120°C and it cannot be used, and even though fluorine oil is preferable from the point of view of compatibility, other oils cannot be used. There are many problems with its properties, and even though perfluoro aliphatic hydrocarbon oil has excellent heat resistance and chemical resistance, due to its low intermolecular cohesive force and nonpolar nature, its viscosity changes significantly with temperature, and its lubricity is poor. Because of its poor lubricity (extreme pressure properties), it cannot withstand use as a lubricating oil, and chlorotrifluoroethylene oligomers are already used as lubricating oils, but even though they have good lubricity, their viscosity changes greatly with temperature. This is because it cannot withstand the use of a lash adjuster. Among these fluorine-based oils, the perfluoropolyether oil is the only one that is the most desirable for its incompatibility and viscosity-temperature characteristics, as well as having no adverse effect on the diaphragm rubber (usually fluorosilicone rubber). It can be said that it is oil.

〔Example〕

Fluorosilicone rubber (Toshi Silicone Co., Ltd.: DY37-
Using a diaphragm manufactured by 049U), the following various hydraulic oils, namely alkyl-modified silicone oil (Shin-Etsu Chemical Co., Ltd.: X-
22-7322), dimethyl silicone oil (Shin-Etsu Chemical Co., Ltd.: KF96)
, perfluoropolyether oil (DuPont: KRYT)
OX, Montefras: Huonpurin Z25, M2S,
Shin-Etsu Chemical Co., Ltd.: Stiflon, etc.) is sealed in a predetermined space and eroded into mineral oil-based multigrade engine oil (150°C), and the amount of engine oil that migrates into the hydraulic oil is reduced by increasing the weight of the adjuster. The results are summarized in Figure 2. As is clear from this figure, perfluoropolyether oil hardly penetrates into fluorosilicone rubber, meaning that engine oil is mixed into hydraulic oil. It was not observed that the amount exceeded the absorption capacity of the diaphragm. In addition, although the compatibility of mineral oil-based multigrade engine oil (150° C.) and perfluoropolyether oil was separately investigated, no substantial compatibility was found between the two.

〔effect〕

As mentioned above, in a sealed lash adjuster that uses hydraulic oil that is substantially incompatible with engine oil, the engine oil does not penetrate the rubber membrane of the diaphragm, and therefore does not mix unilaterally into the hydraulic oil. Since there is no absorption capacity, the absorption capacity of the diaphragm is not exceeded, and the durability is excellent, so it can be said that the significance of this invention is extremely large.

[Brief explanation of drawings]

Figure 1 is a sectional view of the main parts to illustrate the structure of a sealed lash adjuster, and Figure 2 is a diagram showing the relationship between the permeation rate (%) of engine oil into hydraulic oil and immersion time in an example. be. A...Sealed lash adjuster, 6...
...Body guide, 7...Body, 8...
...Plunger, 9...Pressure chamber,
10...Spring, 11...Rod, 12...Protrusion, 13...Passage, 1
4... Check valve, 15... Supply chamber, 16... Diaphragm. Patent applicant: NCH NTOYO HAIRING CO., LTD.

Claims (3)

[Claims] (1) A sealed lash adjuster characterized by using hydraulic oil that is substantially incompatible with mineral oil-based or synthetic engine oil. (2) The sealed lash adjuster according to claim 1, wherein the hydraulic oil is perfluoropolyether oil. (3) The sealed lash adjuster according to claim 1, wherein the hydraulic oil is perfluoropolyether oil having the following repeating structure as a main chain. Note 1) - (C_xF_2_x-O) -_n 2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Here, x and y are both integers from 1 to 4, and n and m are integers that change depending on the viscosity. )