JP3288744B2 - Hydraulic lash adjuster for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic lash adjuster for automatically correcting a valve clearance in a valve train of an internal combustion engine, and particularly to a hydraulic lash adjuster which stops a large amount of fluid in a reservoir associated with a hydraulic chamber when the internal combustion engine is stopped. The present invention relates to a hydraulic lash adjuster that can hold oil.

[0002]

2. Description of the Related Art A valve mechanism in an internal combustion engine is generally susceptible to wear and thermal expansion, and the valve gap changes during operation. Therefore, a hydraulic lash adjuster is used to appropriately correct this gap. As shown in FIG. 11, a conventional hydraulic lash adjuster has a cylinder head 10
The lash adjuster main body 2 (hereinafter, referred to as an adjuster main body) is inserted into the mounting hole 30 formed in the main body 24. The adjuster main body 2 is a body 24 and a plunger assembled in the body 24 so as to be vertically slidable. 26. In the plunger 26, a reservoir 28 is formed which communicates with the oil gallery 32 opening to the mounting hole 30 through the small holes 24b and 27a. The reservoir 28 communicates with the high-pressure chamber 29 through the small hole 27b. The high-pressure chamber 29 is filled with hydraulic oil supplied from the oil gallery 32. Reference numerals 14, 16, and 17 denote a valve body, a cam, and a rocker arm which are components of the valve operating mechanism. When pressure is applied to the hydraulic oil, the check ball 25a in the high-pressure chamber 29 closes the small hole 27b, and the locked plunger 26 forms a rocking fulcrum of the rocker arm 17. When the cam nose 16a presses the rocker arm 17, the rocker arm 17 swings and the valve element 14 slides against the return spring 15 to open the valve. Thereafter, the rotation of the cam 16 causes the valve element 14 to close due to the action of the return spring 15. Reference numeral 23 denotes a plunger spring, and the plunger 26 is held in a state of being constantly in contact with the rocker arm 17 by the plunger spring 23, and performs a correcting operation so that a clearance in the valve train generated due to a thermal deformation or the like becomes zero. It is.

The cylindrical body 6 is accommodated in the reservoir 28, and the inside of the reservoir 28 communicates with the high pressure chamber 29.
8a and an outer chamber 28 communicating with a small hole 27a serving as an oil supply hole.
b. As shown in the figure, even when the lash adjuster main body 2 is inclined, as shown in the figure, the reservoir inner chamber 28 communicating with the high-pressure chamber 29 is provided.
Since a of the oil level does not fall to below the level indicated by the reference numeral H _1, it can hold a large amount of the hydraulic oil in the reservoir 28,
There is no problem that air is sucked into the high-pressure chamber 29 when the operation of the engine is restarted.

[0004] That is, in the case without the reservoir inner chamber 28a, the oil level in the reservoir 28 during stop of the internal combustion engine decreases to the position shown in Figure 11 code of H ₂ same height as the oil supply hole 27a, the engine When the operating oil is sucked from the reservoir 28 due to the restart of the operation, air above the oil level is simultaneously sucked into the high-pressure chamber 29. In particular, when the internal combustion engine stops while the cam nose 16a and the rocker arm 17 are in contact with each other, the plunger 26 is compressed,
The state is the most shortened state (bottomed state). When the engine is restarted from this state, the plunger 26 and the body 24
, The sliding stroke becomes maximum, and the amount of hydraulic oil sucked into the high-pressure chamber 29 becomes the largest. However, since hydraulic oil is not supplied from the internal combustion engine when the engine is stopped, it is almost impossible to secure the amount of oil in the reservoir 28, and air is sucked into the high-pressure chamber 29 when the engine is restarted. Will be the most intense. When the air is sucked into the high-pressure chamber 29, the rigidity of the hydraulic oil to be generated in the high-pressure chamber 29 when the plunger 26 is pressed is extremely reduced (sponge state), and the valve clearance is appropriately corrected. Can not be done. However, in the structure shown in FIG. 11, when the engine is stopped, a large amount of oil (oil level H ₁ ) is secured in the reservoir inner chamber 28a, so that suction of air into the high-pressure chamber 29 when the engine is restarted is prevented. Is to be done.

[0005]

However, according to the prior art described above, the amount of oil in the reservoir 28 when the engine is stopped is limited to the amount secured in the reservoir inner chamber 28a. In the inclined structure, the amount of oil in the reservoir inner chamber 28a is reduced by the amount of the inclination, and there is a possibility that the air above the reservoir will be sucked in at the time of restart.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has a hydraulic lash adjuster capable of retaining a large amount of hydraulic oil in a reservoir communicating with a high-pressure chamber even when the operation of an internal combustion engine is stopped. Is to provide.

[0007]

In order to achieve the above object, in a hydraulic lash adjuster according to the present invention, a cylinder having a bottom and a high-pressure chamber which slides on the inner peripheral surface of the cylinder and is provided at the bottom thereof. A plunger having an upper end as a working end, the plunger having a reservoir communicating with an external oil supply passage through an oil supply hole formed in a side wall thereof, and a valve communicating the reservoir with the high-pressure chamber. A hole is provided, and the high-pressure chamber houses a check valve that opens and closes the valve hole according to pressure reduction and pressure increase of the high-pressure chamber, and a pressing spring that urges the plunger in the extension length direction. In the hydraulic lash adjuster for an internal combustion engine, the reservoir is extended into an upper end portion of the reservoir, and the reservoir is divided into an inner chamber connected to the valve hole and an outer chamber surrounding the inner chamber and connected to the oil supply hole. You Airtight means for preventing movement of oil between the inner and outer chambers is provided between the cylindrical wall and the reservoir forming wall below the oil supply hole formed in the plunger, and the reservoir forming wall above the oil supply hole. Between the cylinder and the cylinder, allows the passage of pressurized hydraulic oil from the outer chamber to the inner chamber when the internal combustion engine is operating, but prevents the passage of oil from the inner chamber to the outer chamber when the internal combustion engine is stopped. Composed of small gaps
The liquid-tight means is provided.

[0008]

During operation of the internal combustion engine, the supply oil acting on the pressure guided from the oil supply hole to the outer chamber is guided to the inner chamber through the liquid tight means constituted by the minute gap . Further, when the internal combustion engine is stopped, the oil supply hole is opened to the atmosphere. However, in the region below the supply hole, the passage of oil is reliably prevented by the airtight means in the region below the supply hole. In the upper region, the movement (leakage) of oil from the reservoir inner chamber to the outer chamber is prevented by the liquid-tight means constituted by minute gaps, so that a large amount of hydraulic oil is stored and held in the reservoir inner chamber communicating with the high-pressure chamber. You.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 show the present invention applied to a valve mechanism of an overhead camshaft (OHC) type internal combustion engine. FIG. 1 is a cross-sectional view of the entire periphery of a hydraulic lash adjuster, and FIG. It is an expanded sectional view.

In these figures, reference numeral 10 denotes a cylinder head, and an air supply passage 1 formed in the cylinder head 10.
2, a valve element 14 is inserted and arranged. The valve element 14 is urged by a valve element return spring 15 in a direction in which the air supply passage 12 is closed, and the upper end of the valve element 14 is in contact with a rocker arm 17 that swings by rotation of a cam 16. Reference numeral 20 denotes a lash adjuster provided adjacent to the valve element 10. The lash adjuster 20 has a structure in which an adjuster main body 22 is inserted into an adjuster mounting hole 30 that opens upward. The adjuster main body 22 includes a cylindrical body 24 that opens upward, and And a plunger 26 that slides in the direction. A band-like concave groove 24 a is provided at a substantially central position in the vertical direction of the outer peripheral surface of the body 24 so that the mounting hole 30 is formed.
An oil gallery 32 to which hydraulic oil is supplied is formed at a position on the inner peripheral surface of the inner surface facing the concave groove 24a. The upper end of the plunger 26 carries the end of the rocker arm 17 on the side opposite to the contact portion with the valve body 14, and serves as a swing fulcrum of the rocker arm 17. A small hole 27a formed in the side wall and a small hole 24 formed in the body 24 are provided in the plunger 26.
reservoir 28 communicating with oil gallery 32 through b
Are formed.

The reservoir 28 communicates with a high-pressure chamber 29 formed between the plunger 26 and the bottom of the body through a small hole 27b, and is opened to the outside air through a small hole 27c formed in the upper end of the plunger. I have. Small hole 27c
Is for supplying the lubricating oil to the valve mechanism by causing the oil in the reservoir 28 to overflow. Reference numeral 23 denotes a plunger spring, reference numeral 25a denotes a check ball for closing and holding the small hole 27b by the urging force of the spring 25b, reference numeral 2
Reference numeral 5c denotes a ball cage. When pressure is applied to the hydraulic oil, the check ball 25a closes the small hole 27b, and the plunger 26 is locked to form a rocking fulcrum of the rocker arm 17. Reference numeral 26a denotes an O-ring mounted on the outer peripheral surface of the body, which maintains the liquid tightness between the body 24 and the mounting hole 30 and prevents the hydraulic oil from leaking from the gap between the two.

In the reservoir 28, the inside of the reservoir 28
A cylindrical body 100 that defines an inner chamber 28a and an outer chamber 28b is housed and integrated. Lower region 100a of cylinder 100
Has an outer shape that engages with the inner peripheral surface 28c of the lower region of the reservoir 28, and this cylindrical lower region 100a is formed with a small hole 27b communicating with the high-pressure chamber 29, as shown in FIG. Together with the disk 102, it is integrated with the plunger inner peripheral surface forming the reservoir lower region inner peripheral surface 28 c by brazing. The brazed portion 112 enters between the plunger 26 and the cylindrical body 100, and the inner chamber 28a and the outer chamber 28b are hermetically sealed by the brazed portion 112. It should be noted that the brazing of the disk 102, the cylinder 100 and the plunger 26
This is performed by heating and melting the brazing filler material charged in the gap between them.

The upper region 100b of the cylinder is provided with the reservoir 2
8 has a smaller outer diameter than the inner peripheral surface 28d of the upper region, and a gap 28e through which oil can sufficiently pass is formed between the inner peripheral surface 28d of the reservoir and the upper region 100b of the cylinder. A supply passage 120 is provided between the outer chamber 28b and the upper end face of the reservoir so as to smoothly supply oil from the outer chamber 28b to the inner chamber 28a. In addition, the supply passage 120 has a liquid-tight structure in which oil in the inner chamber 28a does not leak to the outer chamber 28b when the internal combustion engine in which the inside of the oil gallery 32 is at atmospheric pressure is stopped. That is, as shown in FIG. 3, a notch 28f is provided at the upper end of the cylinder 100, and a pressure acts between the upper end of the cylinder 100 and the upper end surface of the reservoir by the notch 28f. An oil supply path 120 is formed, which is formed of a minute gap that allows the passage of the working oil, but prevents the passage of the oil at atmospheric pressure. The supply passage 120 is a small gap, and allows the passage of the high-pressure hydraulic oil to the inside of the inner chamber 28a during operation of the internal combustion engine. It has a liquid-tight structure in which the oil inside 28a does not leak to the outer chamber 28b side. For this reason, the oil level in the reservoir inner chamber 28a when the engine is stopped does not fall below the position of the small hole 27c at the tip of the plunger shown by the reference symbol H in FIG.
Since a large amount of hydraulic oil is retained in the reservoir inner chamber 28a communicating with the internal combustion engine 9, there is no possibility that air will be sucked into the high-pressure chamber 29 when the internal combustion engine is restarted.

FIGS. 4 and 5 show a second embodiment of the present invention. FIG. 4 is a sectional view of a main part of a plunger, and FIG. 5 is a perspective view of a plunger tip showing a shape of an upper end surface of a reservoir. In this embodiment, a notch is not formed at the upper end of the cylindrical body 100, but a recess 28g is formed at a portion of the upper end surface of the reservoir corresponding to the upper end of the cylindrical body 100.
8g, from the reservoir outer chamber 28b to the inner chamber 28a.
A liquid-tight supply passage 120 is formed, which allows the passage of hydraulic oil to the outside, but prevents oil from leaking from the inner chamber 28a to the outer chamber 28b. That is, during operation of the engine, the operating oil under pressure is supplied through the supply passage 28g to the reservoir outer chamber 28b.
Is guided to the reservoir inner chamber 28a, but when the engine is stopped where no pressure acts on the oil, the passage of the oil from the reservoir inner chamber 28a to the reservoir outer chamber 28b is prevented.

FIG. 6 is a sectional view of a main part of a third embodiment of the present invention. The outer diameter of the upper region 100b of the cylinder 100 is sized to match the inner diameter of the inner peripheral surface 28d of the reservoir upper region, and the inner peripheral surface 28d of the upper region of the reservoir and the cylindrical upper region 1
A small gap 28h is formed between the outer peripheral surfaces of the outer periphery 00b and the reservoir inner chamber 28a is held in a liquid-tight state. An opening 28i is formed in the upper region 100b of the cylindrical body and opens to the inner peripheral surface 28d of the upper region of the reservoir. During operation of the engine, hydraulic oil is supplied from the opening 28i to the reservoir inner chamber 28a. When the engine is stopped, a small gap 28h prevents oil from leaking. That is, the opening 28h constitutes the hydraulic oil supply path 120.

FIG. 7 is a sectional view of a main part of a fourth embodiment of the present invention. Upper cylinder region 100b and reservoir inner peripheral surface 28d
And a notch 28j which forms a hydraulic oil supply passage is formed at the upper end of the cylindrical body 100. At the time of engine operation, this notch 2
Hydraulic oil can be supplied to the reservoir inside chamber 28a via 8j. The rest is the same as the structure shown in FIG. 6, and the description thereof will be omitted by retaining the same reference numerals.

FIGS. 8 and 9 are cross-sectional views of the essential parts of the fifth and sixth embodiments of the present invention. In each of the above-described embodiments, the cylindrical body 100 is fixed to the plunger 26 by brazing in any case. However, in these embodiments, a part of the vertical direction of the cylindrical body 100 (in FIG. 9 is the lower end) 13
Numeral 0 is expandable and contractable in the axial direction, and the cylindrical body 100 has a structure in which the cylindrical body 100 is urged in the vertical extension direction in the reservoir 28.
Further, the outer peripheral surface of the cylindrical body lower region 100a and the inner peripheral surface 2 of the reservoir 2
An O-ring 140 is interposed between 8c to ensure airtightness between the reservoir inner chamber 28a and the outer chamber 28b via the lower end of the cylindrical body. A disk 1 having a small hole 27b which is a communication hole to the bottom surface of the reservoir 28 and the high pressure chamber 29
02 is formed integrally with the plunger 26. For this reason, the plunger 26 is vertically divided into two parts (26a, 26a).
b) In the structure described above, after accommodating the cylindrical body 100 inside, the two 26a and 26b are welded and integrated. Others are the first
The description is omitted by attaching the same reference numerals.

FIG. 10 is a sectional view of a main part of a seventh embodiment of the present invention. In any of the above-described embodiments, the cylindrical body 10
Although the upper and lower ends of the cylinder 0 are in contact with the upper and lower end surfaces of the reservoir 28, in this embodiment, although the upper end of the cylindrical body 100 approaches the upper end surface of the reservoir, the liquid-tight supply passage 120 Are formed. The small gap 28k allows the passage of hydraulic oil from the reservoir outside chamber 28b to the reservoir inside chamber 28a during engine operation, and prevents the passage of oil between the reservoir inside and outside chambers 28a and 28b when the engine is stopped. It has become. The other parts are the same as those of the first embodiment, and the description thereof will be omitted by retaining the same reference numerals.

[0019]

As is apparent from the above description, according to the hydraulic lash adjuster for an internal combustion engine according to the present invention, the hydraulic oil is accommodated and held in a cylinder extending to a position in contact with or close to the upper end surface of the reservoir. As a result, a large amount of oil can be retained in the reservoir communicating with the high-pressure chamber even when the engine is stopped, and no air is sucked into the high-pressure chamber when the engine is restarted. Various problems associated with suction are eliminated.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention and is a cross-sectional view of a valve mechanism of an OHC type internal combustion engine.

FIG. 2 is an enlarged sectional view of a main part in a reservoir.

FIG. 3 is a perspective view of an upper end portion of a cylindrical body.

FIG. 4 is a sectional view of a main part of a second embodiment of the present invention.

FIG. 5 is a perspective view of the upper end of the plunger of the embodiment.

FIG. 6 is a sectional view of a main part of a third embodiment of the present invention.

FIG. 7 is a sectional view of a main part of a fourth embodiment of the present invention.

FIG. 8 is a sectional view of a main part of a fifth embodiment of the present invention.

FIG. 9 is a sectional view of a main part of a sixth embodiment according to the present invention.

FIG. 10 is a sectional view of a seventh embodiment of the present invention.

FIG. 11 is a sectional view of a main part of a conventional hydraulic lash adjuster.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Cylinder head 17 Rocker arm 20 Hydraulic lash adjuster 22 Lash adjuster main body 23 Pressing spring 24 Body which is a cylinder 25a Check valve 26 Plunger 27a Small hole which is oil supply hole 27c Small hole for oil overflow 28 Reservoir 28a Reservoir inner chamber 28b Reservoir outer Chambers 28f, 28g, 28h, 28i, 28j, 28k Liquid-tight supply path 29 High-pressure chamber (hydraulic chamber) 30 Rush adjuster mounting hole 32 Oil gallery 100 Cylindrical body

Claims (1)

(57) [Claims] 1. A cylinder having a bottom and a plunger which slides on an inner peripheral surface of the cylinder to define a high-pressure chamber at the bottom and has an upper end as an operating end. A reservoir communicating with an external oil supply passage through a supplied oil supply hole, and a valve hole communicating the reservoir with the high-pressure chamber, and the valve is provided in the high-pressure chamber according to pressure reduction / pressure increase in the high-pressure chamber. In a hydraulic lash adjuster for an internal combustion engine, comprising a check valve for opening and closing a hole and a pressing spring for urging a plunger in an extension direction, the reservoir extends to an upper end of the reservoir, A cylindrical body which is partitioned into an inner chamber connected to the valve hole and an outer chamber surrounding the inner chamber and connected to the oil supply hole, and a reservoir forming wall and a cylinder below the oil supply hole formed in the plunger. Between the body, inside and outside Airtight means for preventing oil from moving between the chambers is provided, while between the cylinder wall and the reservoir forming wall above the oil supply hole, the hydraulic oil pressurized from the outer chamber to the inner chamber during operation of the internal combustion engine is provided. While allowing the passage, preventing the passage of oil into the outer chamber from the inner chamber when the internal combustion engine is stopped fine
A hydraulic lash adjuster for an internal combustion engine, wherein a liquid-tight means constituted by a small gap is provided.