JPH03194106A - Direct acting hydraulic lash adjuster - Google Patents

Abstract

PURPOSE:To prevent leakage of working oil by providing a ring-shaped float whose specific gravity is smaller than that of the working oil in an auxiliary reservoir provided around a hydraulic unit inside a bucket and by blocking an hole above the working oil surface through floating of the ring-shaped float. CONSTITUTION:A direct acting valve mechanism is constituted by a hydraulic lash adjuster, made of a bucket X and a hydraulic unit Y, which is put between a cam 60 and a valve 61, and the hydraulic unit Y is formed in a plunger 30 with the plunger 30 in the shape of a cylinder having a bottom and a body 32 engaged on it and has a main reservoir 3 communicating to a high-pressure chamber 4 through an oil hole 31. The bucket X is attached around the hydraulic unit Y and separated by a partition sleeve 20 from an auxiliary reservoir 2 communicating to the main reservoir 3 by a recess 22. In this case, when a float 1 in the shape of a ring is inserted into the auxiliary reservoir 2 and a hole 5a for supply is above an oil surface H, the hole 5a is blocked by the float 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a direct-acting hydraulic lash adjuster in which a hydraulic unit of the lash adjuster is built into a bucket.

[Conventional technology]

The valve train in an internal combustion engine is generally susceptible to wear and thermal expansion, and the valve gap changes during operation, which adversely affects output and noise. Therefore, hydraulic lash adjusters have come to be used to appropriately correct this gap.

Among these, for the purpose of reducing the weight of internal combustion engine equipment, a hydraulic lash adjuster as shown in Figure 3 is also used in a direct-acting valve mechanism in which the cam is configured to strike directly against the end of the valve shaft. ing.

This hydraulic lash adjuster is composed of a bucket X and a lash adjuster hydraulic unit Y housed inside the bucket X, and is interposed between the cam (60) and the shaft end of the valve (61). The hydraulic unit Y of the lash adjuster includes a bottomed cylindrical plunger (30) having an oil hole (31) at the bottom, and a ring that is slidably mounted around the outer circumference of the plunger (30). A similarly bottomed cylindrical body (32) forming a high pressure chamber (4) therebetween, and the high pressure chamber (4).
4) an elastic body (33) interposed within the body to bias the body (32) toward its closed surface; and an elastic body (33) disposed within the high pressure chamber (4) to open and close the oil hole (31). The check valve (34) that controls the check valve (34), the valve spring (35) that holds the check valve (34), and the check valve cage (36)
). This hydraulic unit Y is built into the bucket X, and the face disk (
21) There is a main reservoir (3) for oil between the JG surface and the hollow part of the plunger (30), and an overflow recess ( 22) forms an auxiliary reservoir (2) communicating therewith, and hydraulic oil is supplied thereto through the oil feed hole (70) of the cylinder head and the perforation (5a) of the bucket X. On the other hand, the cam (60) is attached to the face disk (21) of the bucket
1) The shaft ends contact the closed surfaces of the body (32), and the cam (60) directly hits the valve (61) shaft end via the hydraulic lash adjuster. When the lash adjuster applies pressure to the hydraulic oil filled in the high pressure chamber (4), the volume of the hydraulic oil itself is compressed, and the elastic effect and pressure due to leakdown to the outside are further added, resulting in volume compression. This method utilizes the rigidity effect of the hydraulic oil that occurs when the hydraulic fluid stops moving further, and also generates a repulsive force that tends to stretch the elastic body (33) interposed in the high pressure chamber (4) when the pressure is released. This corrects the gap in the valve mechanism caused by thermal deformation or the like to zero.

[Problem that the invention seeks to solve]

On the other hand, in the above-mentioned direct-acting hydraulic lash adjuster that is installed in an inclined position or in a direct-acting hydraulic lash adjuster in which the engine is stopped due to an inclined condition, when the perforation (5a) stops facing upward, the Since the internal cavity of the sub-reservoir (2) communicates with the outside through the perforation (5a), as shown in FIG. (2) Internal hydraulic oil leaks through the gap with the sleeve (20) that constitutes the partition wall. In addition, for buckets with air vent holes (5b) provided on or near the face disk (21) of bucket X, even if the entire lash adjuster becomes nearly vertical and the engine stops, The internal cavity of the sub-reservoir (2) communicates with the outside through this air vent hole (5b), causing a similar leakage of hydraulic oil. Furthermore, if there is a hole (5) for air release or hydraulic oil supply at a position lower than the oil level H in the sub-reservoir (2),
It is conceivable that air enters through the other air vent hole (5b) and the hydraulic oil supply hole (5a), causing hydraulic oil to leak also from the lower hole (5).

The present invention has been devised in view of the above-mentioned problems of the prior art, and aims to solve the above-mentioned problems by providing a structure that can prevent the above-mentioned leakage of hydraulic oil.

4- [Means for solving the problem] Therefore, in the present invention, as shown in FIG. 1) is composed of a material with a specific gravity lower than that of the supplied hydraulic oil, so that the sub-reservoir (
2), so that the float (1) can close the holes (5) provided on the wall of the bucket X that are above the hydraulic oil level H. This is what I did.

[For production]

The above-mentioned hydraulic oil leakage occurred because the perforation (5) of either one (for hydraulic oil supply or air release) provided in bucket This occurs when the air gap above the oil level H communicates with the outside through these perforations (5), and if these perforations (5) are blocked by hydraulic oil or by some other means. If it is blocked, there will be no hydraulic oil leakage as described above. As in the configuration of the present invention, the perforation (
If the float (1) blocks this when the position of 5) is high,
Even if hydraulic oil were to leak, it would not be possible because negative pressure would be generated inside. On the other hand, when these perforations (5) are located lower than the curved surface H, the perforations (5)
5) is blocked by the viscous resistance of the hydraulic oil itself, so there is no intrusion of air and therefore no leakage of the hydraulic oil occurs.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described based on the accompanying drawings.

FIG. 2 shows a valve train installed obliquely in the horizontal direction on an internal combustion engine. This valve train is a direct-acting valve train in which a hydraulic lash adjuster composed of a bucket X and a hydraulic unit Y is interposed between a cam (60) and a valve (61).

The hydraulic unit Y includes a bottomed cylindrical plunger (30) having an oil hole (31) at the bottom;
), the body (32) is slidably mounted on the outer periphery of the body (32) and forms a high pressure chamber (4) between the body (32) and the bottom part;
0), and the high pressure chamber (
4), and has a main reservoir (3) that communicates with the high pressure chamber (4), as well as an elastic body interposed in the high pressure chamber (4), a check valve that controls the opening and closing of the oil hole (31), a check valve spring, a cage, etc. It also has as its structure.

Furthermore, the bucket
A secondary reservoir (2) communicates with the primary reservoir (3) by
is formed by the septum sleeve (20). Then, in the peripheral wall surface of the bucket X (shown in the upper part of the peripheral wall surface of the bucket ) are drilled.

In this embodiment, an annular float (1) is inserted into the sub-reservoir (2), and is loosely fitted around the hydraulic unit Y (7). However, in this embodiment, an annular projection (23) projects from the inner circumferential wall surface of the bucket X toward the sub-reservoir (2), and the float (1) ) will have its horizontal movement restricted.

This float (1) is made of engineering plastic, which has a specific gravity lower than that of the hydraulic oil, and has a sub-reservoir (
2) Float in the hydraulic oil inside.

In this embodiment having the configuration shown above, as shown in the drawings, the entire valve mechanism is installed in a horizontally inclined state, so the float (1) is attached to the sub reservoir (2). Float inward and upward.

Therefore, when the internal combustion engine is stopped, if the supply hole (5a) is above the hydraulic oil level H as shown in the figure, the float (], ) will close the hole (5a).

By blocking the perforations (5a) in this way, the hydraulic oil will not leak to the outside, so even if the internal combustion engine is stopped without hydraulic oil being supplied from the cylinder head side, the oil in the reservoirs (2) and (3) will not leak out. Sufficient operating oil will be ensured. Therefore, when the internal combustion engine is restarted and hydraulic oil is sucked into the high pressure chamber (4) (particularly when the engine is restarted from the so-called bottomed state where the hydraulic unit Y is compressed and the most shortened state), the high pressure chamber (4) 4) Air is not sucked into the interior.

On the other hand, if the hole (5a) is located below the hydraulic oil level H, even if it is not blocked by the flow +- (1), the hole (5a) will resist the viscous resistance of the hydraulic oil itself. Since the hole is blocked by the hole, no external air can enter from there, and therefore, there is no leakage of hydraulic oil.

〔Effect of the invention〕

As detailed above, according to the present invention, when the engine is stopped, if the holes for supplying hydraulic oil and for removing air in the bucket are located above the level of hydraulic oil in the sub-reservoir. Since the annular float floating in the hydraulic oil closes the hole, the hydraulic oil in the reservoir will not leak to the outside, and when trying to suck the hydraulic oil into the high pressure chamber at restart, Air is no longer sucked in, and the decrease in rigidity of the hydraulic lash adjuster is kept to a minimum.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of the basic configuration of the hydraulic lash adjuster of the present invention used in a direct-acting valve train, and Fig. 2 is a cross-sectional view of a direct-acting valve train installed horizontally inclined in an internal combustion engine. 3 is a sectional view showing an example of the structure of a hydraulic lash adjuster part according to an embodiment of the present invention; FIG. 3 is a sectional view showing an example of the structure of a direct-acting valve mechanism equipped with a hydraulic lash adjuster; FIG. 4 is an explanatory diagram showing a leakage state of hydraulic oil in such a valve mechanism. In the figure, (1) is the annular float, (2) is the sub-reservoir, and (3) is the annular float.
) is the main reservoir, (4) is the hyperbaric chamber, (5a) (5b)
(30) is a plunger, (31) is an oil hole, (3
2) indicates the body, X indicates the bucket, Y indicates the hydraulic unit, and H indicates the oil level. 2nd Figure 31-

Claims (1)

[Claims] A hydraulic unit for a lash adjuster is built in the bucket, and a sub reservoir is installed around the hydraulic unit inside the bucket to supply hydraulic oil to the main reservoir on the hydraulic unit side, and In a direct-acting hydraulic lash adjuster in which a wall surface is provided with a hole for supplying hydraulic oil or a hole for venting air and supplying hydraulic oil, an annular float having a specific gravity smaller than that of the hydraulic oil is installed in the sub-reservoir, A direct acting hydraulic lash adjuster characterized in that the annular float can close a hole above the level of the hydraulic oil when floating in the hydraulic oil.