JPH0729204Y2 - Hydraulic lash adjuster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a hydraulic lash adjuster that discharges oil passing through the inside to lubricate a lubrication surface. More specifically,
The present invention relates to a hydraulic lash adjuster in which a sealing means is provided between a plunger and a separator in a lash adjuster having a separator to prevent oil in the reservoir chamber from leaking to the outside when left for a long time.

(Prior Art) The general operation of the hydraulic lash adjuster will be described below.

In general internal combustion engines, it is necessary to provide a valve clearance in consideration of the difference between the expansion of the cylinder head and the expansion of the valve operating mechanism due to heat, but if this valve clearance is not appropriate, noise will be generated during engine operation. Or a loss of horsepower may occur due to blown raw gas. A hydraulic lash adjuster is known as a means for solving such a problem. The hydraulic lash adjuster always keeps the valve clearance at zero during operation of the valve operating mechanism.
It absorbs changes in expansion due to temperature, prevents noise and blowout of raw gas, and realizes stable operation of the valve operating mechanism.

In the valve mechanism, the cam shaft is arranged in the cylinder head, and the cylinder block has an OHC type and a cam shaft that directly drive the intake and exhaust valves with or without a rocker arm.
There is an OHV type that drives an intake / exhaust valve via a push rod and rocker arm. Whether it is an OHC type or an OHV type, when the engine is operating, the hydraulic lash adjuster and the intake / exhaust valve function integrally according to the rotation of the cam.

When the engine is stopped, the cam abuts its cam surface directly on the upper surface of any hydraulic lash adjuster or indirectly via a rocker arm. Therefore, when the cam nose (protrusion of the cam surface) directly or indirectly contacts the upper surface of the hydraulic lash adjuster, the urging force of the valve spring that urges the intake / exhaust valve to the closed position is relatively large. The hydraulic lash adjuster as a whole is in a state where a pressing force mainly in the axial direction is always applied. Therefore, if this stopped state continues for a long time, the oil in the high pressure chamber gradually leaks from the gap between the body of the lash adjuster and the plunger, and finally the high pressure chamber is in the most crushed state, that is, the volume of the high pressure chamber becomes the minimum. It becomes a state (so-called "bottoming out state").

Then, when the engine is restarted, the volume of the high pressure chamber of the hydraulic lash adjuster stopped at the cam nose position increases, the high pressure chamber becomes negative pressure, the check ball opens, and oil is sucked from the reservoir to the high pressure chamber. When the pressure in the high-pressure chamber reaches a predetermined pressure (pressure during normal operation) again, the check valve closes. In this state, the hydraulic lash adjuster will perform a normal expansion / contraction operation. Acting in this manner, the hydraulic lash adjuster automatically adjusts to properly fill any gaps and properly seat the valve. As a result, noise generation can be eliminated.

In particular, when the cam nose starts, air is suddenly sucked into the high pressure chamber from the reservoir chamber immediately after the start via the oil passage in the cylinder head, etc., and the high pressure chamber cannot maintain rigidity, so-called "sponge state", It may not follow the displacement and may generate an abnormal noise. Therefore, it is important to prevent the intake of air into the high pressure chamber.

In such a conventional lash adjuster, in order to prevent air from being sucked into the high pressure chamber, for example, a separator is fitted in the plunger cap, and air introduced from the outside into the lash adjuster is often mixed. The oil is oriented upwards along the perimeter shape of the separator. As a result, oil that contains a large amount of air enters the reservoir chamber that is defined between the separator and the plunger and plunger cap, and the air that is mixed in with the oil does not enter the high pressure chamber when the lash adjuster operates. There is.

(Problems to be solved by the invention) In the conventional lash adjuster having the above-described function, the oil in the reservoir chamber is externally exposed through the contact surface between the plunger and the plunger cap and the sliding surface between the plunger cap and the main body. If the lash adjuster is left for a long time (especially when the cam nose is stopped), the oil in the reservoir chamber will leak from the interface between the plunger and the plunger cap. As a result, when the engine is restarted, the external supply oil, which is often mixed with air, easily enters the reservoir chamber, and particularly, the air easily enters the high pressure chamber of the lash adjuster that starts from the bottomed state. Sound may be generated.

In addition, if the lash adjuster is installed tilted,
The outflow of oil in the reservoir chamber is remarkable, and in particular, the larger the inclination, the more likely it is to be disadvantageous for air intrusion. Therefore, in this case, the risk of abnormal noise is further increased.

When the cam nose starts after the oil has leaked from the lash adjuster to the outside as described above, air is rapidly sucked from the reservoir chamber into the high pressure chamber immediately after the start via the oil passage in the cylinder head etc. The rigidity cannot be maintained, that is, a so-called “sponge state” occurs, and it is possible that not only the cam displacement cannot be followed but abnormal noise is generated, but also the achievement of the function of adjusting the valve clearance is affected.

As mentioned above, in the conventional lash adjuster,
The separator does not allow the oil supplied from the outside containing a large amount of air to directly enter the lower part of the reservoir chamber, so that the air in the oil does not enter the high pressure chamber due to the operation. Therefore, in this case, since the sealability between the plunger and the plunger cap and between the plunger cap and the separator is not ensured, oil may leak from the reservoir chamber when left for a long period of time, and abnormal noise may occur at the time of starting.

Further, in order to solve the above-mentioned problems, there is also one in which a separator and a plunger are integrally formed as disclosed in JP-A-61-237807. However, in this case, although it is effective in reducing the amount of oil in the reservoir chamber, that is, in removing oil, it is very difficult to form the plunger and the separator integrally from the time of forging. However, new problems arise, such as difficulty in Therefore, such a method was not a fundamental countermeasure.

From the above, the purpose of the present invention is to prevent the oil in the reservoir chamber of the lash adjuster from leaking to the outside from between the plunger and the plunger cap at the time of long-term stoppage, so that the level of the oil level in the reservoir chamber can be improved. By providing a hydraulic lash adjuster that keeps it as high as possible and prevents air from being sucked into the lash adjuster, especially into the high-pressure chamber even when restarting from the cam nose, and suppresses abnormal noise. is there.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the hydraulic lash adjuster of the present invention is held in a cylinder head (30) to absorb and discharge the rotational displacement of a cam without producing a valve clearance. Valve (2
4) A hydraulic lash adjuster that is transmitted to a cup-shaped body (1) having an oil introduction port (1a) for introducing oil from the outside, and is axially slidably fitted in the body. A plunger (3,43,53), and a plunger cap (2,42,52) which is a separate body from the plunger and is fitted in the body above the plunger so as to be slidable in the axial direction. A separator (15, 45, 55) fitted to the plunger cap and the inner peripheral surface of each of the plungers and dividing the reservoir chamber (16) defined between the plunger and the plunger cap into two parts. And an annular groove (15d, 43a, 53a) is provided between the separator and the plunger, and a seal member (17, 47, 57) made of an elastic body is attached to the annular groove. It is characterized by that.

(Operation) With the above configuration, oil does not leak outside between the plunger and the plunger cap even when the engine is stopped (when left for a long time), and the oil level in the reservoir chamber is maintained at a high level. It

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same parts are designated by the same reference numerals. 1 and 2 are both longitudinal sectional views of the lash adjuster for showing the oil level in the reservoir chamber when left for a long time.

FIG. 1 is an axial sectional view showing a first embodiment in which the present invention is applied to an end pivot type hydraulic lash adjuster (hereinafter, “hydraulic type” is abbreviated as “lash adjuster”). Fig. 1 shows the lash adjuster 10
FIG. Further, FIG. 1 shows the crush adjuster 10 in the most crushed state, that is, the so-called “bottomed-out state”. The lash adjuster 10 is a cup-shaped body 1 having a substantially cylindrical shape opened upward, a substantially cylindrical plunger 3 slidably fitted in the body 1, and a body 1 above the plunger 3 fitted therein. Plunger cap 2. A spiral groove 1b for venting air is engraved on the outer periphery of the lower portion of the body 1. The groove 1b is provided to facilitate insertion of the lash adjuster into the pocket of the cylinder head described with reference to FIG.

The plunger cap 2 is provided with an oil ejection port 2a at its tip and is held by a cap retainer 4 so as not to come off from the body 1. The plunger 3 and the plunger cap 2 slide substantially integrally when the lash adjuster operates.

The plunger cap 2 is composed of a small diameter portion 2b having a small diameter inner diameter provided with an oil ejection port 2a at its tip and a large diameter portion 2c having a large diameter inner diameter continuous with the small diameter portion 2b. An oil port 2d is provided on the boundary between the large diameter portion 2c and the small diameter portion 2b.
The inner peripheral surface of the boundary portion between the large diameter portion 2c and the large diameter portion 2c is a tapered portion 2e.

Therefore, the externally supplied oil introduced from the oil introduction port 1a passes through the oil port 2d through the circumferential groove 1c, passes through the inside of the small diameter portion 2b of the plunger cap 2, and is discharged from the oil ejection port 2a. To be done.

On the inner peripheral surface of the large diameter portion 2c, the cylindrical portion 15a of the separator 15 is
Are closely fitted by press fitting. Separator 15 is
The reservoir chamber described later is divided into two chambers. The separator 15 is composed of a cylindrical portion 15a and a conical portion 15b having a substantially truncated cone shape that is integral with the cylindrical portion 15a and has a reduced diameter from the cylindrical portion 15a, and a through hole 15c is formed substantially at the center of the top of the conical portion 15b.
Is provided. The separator 15 has a function of preventing oil supplied from the outside, which is often mixed with air and introduced through the oil port 2d, from directly entering the reservoir chamber 16. At this time, as is clear from FIG. 1, the space defined between the truncated cone portion 15b and the conical taper portion 2e on the inner peripheral surface of the plunger cap 2 quickly moves the oil introduced from the outside upward. And has a function of preventing entry into the reservoir chamber 16.

An end portion of the cylindrical portion 15a opposite to the conical portion 15b extends to an inner peripheral surface of the plunger 3, that is, an inner diameter portion, and a tip thereof extends to a wall portion 3a of the plunger 3 described later. Cylindrical part
15a is provided with an annular groove 15d that is recessed radially inward in the inner diameter portion of the plunger 3, that is, an annular groove, and the groove 15d has a sealing member 17 such as an O-ring.
Is attached to seal between the inner diameter of the plunger 3 and the separator 15. Therefore, it is possible to prevent the oil in the reservoir chamber 16 from leaking out from the contact portion between the plunger 3 and the plunger cap 2. As a result, when left for a long time,
The oil spill in the reservoir chamber 16 can be effectively prevented.

A wall portion 3a, which divides the inside of the body 1 into two spaces and is provided with an orifice 5, is provided in the middle of the plunger 3 in the axial direction.
There is a high pressure chamber between the wall 3a and the bottom of the body 1.
11 are defined. In the high pressure chamber 11, the check ball 6 seated on the orifice 5 is a retainer spring 8 attached to seat the check ball 6 on the orifice 5,
A retainer 7 that holds the check ball 6 and the retainer spring 8 and a plunger spring 9 that abuts the retainer 7 against the wall portion 3a and biases the plunger 3 toward the plunger cap 2 side are mounted.

The check ball 6 opens and closes the orifice 5 in accordance with the pressure difference between the high pressure chamber 11 and the reservoir chamber 16 to introduce a predetermined amount of oil from the reservoir chamber 16 into the high pressure chamber 11.

As can be seen from the above description of the configuration, in the conventional case, even if a separator is provided, the oil in the reservoir chamber 15 may be slightly removed from the contact portion between the plunger 3 and the plunger cap 2, that is, the contact portion when left for a long time. Each oil leaks out, so-called “oil spills”, and the oil level in the reservoir chamber 16 drops considerably. When the oil is introduced from the outside while the oil is leaking in this way, the introduced oil from the outside directly enters the reservoir chamber 16.

However, with the configuration of the present embodiment, since the sealing means is provided, the oil in the reservoir chamber 16 does not leak to the outside, so that even when the cam nose is started, the entrainment of air in the high pressure chamber 11 is effectively prevented. it can.

Here, with reference to FIG. 4, the operation when the lash adjuster 10 of the first embodiment is assembled to the cylinder head will be described as an example. The cylinder head shown in FIG. 4 is for a vertical engine, but it goes without saying that it can be used for other types of engines such as a V-type engine. It goes without saying that the lash adjuster of the second embodiment described below can also be incorporated.

A substantially cylindrical pocket 28 provided on the cylinder head 30
The lash adjuster 10 is fitted in. Pocket 28
An oil passage 29 through which engine oil or the like is introduced is provided at a position corresponding to the oil introduction port 1a of the body 1. The tip of the plunger cap 2 is in contact with one end of the rocker arm 20. A cam 21 rotatably supported by a rotary shaft 23 is rotatably in contact with a surface 20b of the rocker arm 20. In FIG. 4, a cam having a cam nose 22 is shown.
The circular cam surface 27 of 21 is shown in contact with surface 20b and stopped. Since the through hole 20a is provided at one end of the rocker arm 20 that abuts on the plunger cap 2 so as to face the oil jet port 2a, the engine oil passing through the inside of the lash adjuster 10 can be used as the oil jet port 2a and the through hole.
Lubricate the sliding surface between the cam surface and the surface 20b via 20a.

One end of an intake / exhaust valve 24 is engaged with the other end of the rocker arm 20. The intake / exhaust valve 24 has an intake / exhaust port formed by a valve spring 25.
It is urged to close 26. From the state shown in FIG. 4, the cam 21 rotates and the cam nose 22 moves to the rocker arm.
When the engine is stopped for a long time in the so-called "when the cam nose is stopped" in contact with 20, the above-mentioned bottoming state is reached. In this state, when the engine is started, the lash adjuster 10 rapidly expands and sucks the air above the reservoir chamber 16 together with the oil, but the separator 15 is provided and the separator 15 and Since the sealing means is provided between the plunger 3 and the plunger 3, it is possible to secure a certain amount of oil in the reservoir chamber 16 and to prevent the external oil from directly entering the reservoir chamber 16, so that the rush adjuster 10 can be rapidly supplied. Air is not sucked into the high-pressure chamber 11 at least.

A lash adjuster 40 according to a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, most of the constituent elements are the same as in the first embodiment, so
Descriptions of the same parts are omitted.

The difference from the first embodiment is that there is no annular groove in the cylindrical portion 45a of the separator 45, which is composed of the cylindrical portion 45a extending to the inner diameter portion of the plunger 43 and the truncated cone portion 45b. Instead, in this embodiment, an annular step 43a is formed at the end of the plunger 43 that abuts the plunger cap 42.
A (annular groove) is provided, and a seal member 47 such as an O-ring is interposed in this step portion 43a. Therefore, as can be seen from FIG. 2, the outer peripheral surface of the cylindrical portion 45a of the separator 45 and the plunger 4 are
3 and between the plunger 43 and the plunger cap 42, and between the cylindrical portion 45a and the plunger cap 42 are well sealed by the seal member 47, from the contact portion between the plunger 43 and the plunger cap 42. It is possible to prevent the oil in the reservoir chamber from leaking.

Finally, with reference to FIG. 3, a lash adjuster 50 according to a third embodiment of the present invention will be described. In the third embodiment, most of the constituent elements are the same as in the second embodiment, so description of the same parts will be omitted.

The difference from the first embodiment is that there is no annular groove in the cylindrical portion 55a of the separator 55, which is composed of the cylindrical portion 55a extending in the inner diameter portion of the plunger 53 and the truncated cone portion 55b. Instead, in this embodiment, an annular groove 53a (annular groove) is engraved in the inner diameter portion of the plunger 53, and a seal member 57 such as an O-ring is interposed in the groove 53a. Therefore, as can be seen from FIG. 3, the seal member 57 is satisfactorily sealed between the outer peripheral surface of the cylindrical portion 55a of the separator 55 and the plunger 53, so that the contact portion between the plunger 53 and the plunger cap 52 becomes the reservoir. The oil in the room can be prevented from leaking.

The following can be said in common with each of the above-described embodiments. When the separator is fitted by press fitting, the inner peripheral surface of the plunger cap has a certain degree of roundness.Therefore, by pressing the separator into the inner diameter of the plunger cap, the circularity of the seal part of the separator and Concentricity with the inner diameter of the plunger is secured, and the sealability between the separator and the plunger is further improved.

(Effect of the Invention) According to the hydraulic lash adjuster of the present invention described above, the following effects can be obtained.

The oil in the reservoir chamber of the lash adjuster does not leak out during a long-term stop, that is, when left for a long time,
A sufficient amount of oil can be retained in the reservoir chamber. Therefore, even when the engine is restarted after being left for a long period of time, a certain amount of oil is secured in the reservoir chamber, so that it is possible to prevent external air from directly entering the high pressure chamber.

Further, since the separator is provided at a suitable position, it becomes easy to guide the oil supplied from the outside to the upper part inside the plunger cap during normal operation, and it is possible to prevent the oil in the reservoir chamber from being adversely affected.

From the above, it is possible to prevent air from being sucked into the lash adjuster, particularly to the high pressure chamber, and to suppress the generation of noise even during normal operation and restarting from the cam nose.

Therefore, it is possible to provide the lash adjuster which maintains the rigidity in the high pressure chamber and is stable in operation.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the hydraulic lash adjuster of the present invention, FIG. 2 is a partial sectional view showing a hydraulic lash adjuster of the second embodiment, and FIG. FIG. 4 is a partial cross-sectional view showing a hydraulic lash adjuster of a third embodiment, and FIG. 4 is a cross-sectional view showing the hydraulic lash adjuster of each embodiment of the present invention assembled in a cylinder head. [Explanation of symbols for main parts] 1 …… Body 1a …… Oil inlet 2,42,52 …… Plunger cap 3,43,53 …… Plunger 11 …… High pressure chamber 15,45,55 …… Separator 16… … Reservoir chambers 17, 47, 57 …… Seal members 10, 40, 50 …… Hydraulic lash adjuster

Claims (1)

[Scope of utility model registration request] 1. A hydraulic lash adjuster held in a cylinder head for transmitting rotational displacement of a cam to an intake / exhaust valve without producing a valve clearance, and having an oil introduction port for introducing oil from the outside. A cup-shaped body, a plunger slidably fitted in the body, and a plunger that is a separate body from the plunger and is slidably fitted in the body above the plunger. A cap, and a separator that fits on the plunger cap and the inner peripheral surface of each of the plungers and that divides the reservoir chamber defined between the plunger and the plunger cap into two. An annular groove is provided between the separator and the plunger, and a sealing member made of an elastic body is attached to the annular groove. Hydraulic lash adjuster for.