JPH0223217A - Hydraulic rush adjustor - Google Patents

Abstract

PURPOSE:To prevent air from mixing into oil by upwardly enlarging an upper wall of an oil reservoir so provided on a rocker arm as to be horizontal at the time of closing a valve, and constructing such that an oil level in the oil reservoir is in a gap thereof enlarged upward. CONSTITUTION:A hydraulic rush adjustor, provided on a rocker arm 20 of a valve system of a horizontal opposed engine, is composed of a bottomed cylindrical body 11 having an oil port 15 on a bottom 11a thereof, a plunger 12 inserted therein and partitioningly forming a high pressure chamber 13, a check valve 16 opening/closing the oil port 15 in the high pressure chamber 13, and the like. Oil is supplied into an oil reservoir 22 formed on the rocker arm 20 through an oil introducing passage 23. An upper wall of the oil reservoir 22, including the part on the side of the body bottom 11a, is enlarged in the direction of the oil introducing passage 23 extending obliquely upward from the oil reservoir 22. Then, an oil level H is located within a gap 10a of the oil reservoir 22 enlarged in the direction of the introducing passage 23, while an air bleeder port 24 is opened at the position of the oil level H.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in a hydraulic lash adjuster that automatically corrects a valve gap in a valve train for an internal combustion engine using hydraulic pressure and elastic force of an elastic member.

[Conventional technology]

A valve train in an internal combustion engine is generally susceptible to wear and thermal expansion, and the valve clearance changes during operation. Therefore, hydraulic lash adjusters have come into use to appropriately correct this gap.

FIG. 8 shows an example of this hydraulic lash adjuster, which includes the rocker arm 2.
It is arranged so as to fit into a lash adjuster support hole 21 provided at 0.

To explain the structure in detail, the body 11 of the hydraulic lash adjuster is composed of a bottomed hollow cylinder having a closed bottom part 11a and an open end on the opposite side, and a plunger 12 is fitted into the hollow part. The plunger 12 has a portion extending outwardly therefrom. A high pressure chamber 13 is formed between the body bottom 11a and the plunger 12, and an elastic body 14 is interposed within the high pressure chamber 13 to urge the plunger 12 toward the open end of the body 11. The body bottom 11a has an oil hole 15 for introducing oil from the outside.
A check valve 16 and a check valve cage 17, which control the opening and closing of the oil hole 15, are connected to the high pressure chamber 13.
It is located inside. Furthermore, the oil reservoir chamber 22 is located at the bottom of the body 1.
It is provided inside the rocker arm 20 adjacent to the rocker arm 1a, and is connected to the high pressure chamber 13 via the oil hole 15. Oil supplied to such a hydraulic lash adjuster is supplied from an oil guide path 23 provided in the rocker arm 20, and is led to the high pressure chamber 13 via the oil reservoir chamber 22.

Since the outer end of the plunger 12 is placed in contact with the valve 30, the rocker arm 2
When actuated, valve 30 is pushed out through the hydraulic lash adjuster.

At this time, if the check valve 16 closes the oil hole 15 and stiffens the oil trapped in the high pressure chamber 13,
Thereafter, the plunger 12 moves together with the rocker arm 2° to push out the valve 30, thereby opening the valve. Further, when the valve is closed, the valve 30 is seated as the rocker arm 20 rotates, and the force of the valve spring 31 on the plunger 12 is eliminated. Therefore, the plunger 12 slides toward the opening end of the body 11 due to the repulsive force of the elastic body 14 in the contracted state, and the hydraulic lash adjuster is operated until the gap in the valve mechanism caused by thermal deformation or the like is reduced to zero. Stretch and correct.

[Problem that the invention seeks to solve]

As is well known, in order for the hydraulic lash adjuster to maintain normal operation, it is necessary for the oil in the high pressure chamber 13 to maintain its rigidity at all times, and for this reason, the oil introduced into the high pressure chamber 13 is free from air. Please be very careful.

However, the valve 30 may be in an open state when the multi-cylinder engine is stopped, and at this time the valve spring 31 of the valve 30 continues to apply a load to the plunger 12 of the lash adjuster. Therefore, the plunger 12 continues to contract into the body 11, and the oil in the high pressure chamber 13 leaks out from the gap between the body 11 and the plunger 12. If the engine is restarted from such a state and oil is suddenly introduced into the high pressure chamber 13 in the first cam cycle, the oil sump chamber 22 will not be supplied from the oil guide path 23 while the engine is stopped. The oil level inside the oil hole 15 is low.
If the oil is located nearby, the air above the oil surface will be guided into the high pressure chamber 13 along with the oil, resulting in an extreme decrease in the rigidity of the oil.

Furthermore, this tendency becomes even more pronounced when these valve train mechanisms are used between horizontally opposed or V-type machines.

That is, in the above-mentioned engine, since the cylinder is installed in a horizontal or inclined state, the valve 30, the plunger 12 of the valve operating mechanism that presses the valve to open and close it, and the oil reservoir chamber 22 are also installed in a horizontal or inclined state. It is often installed in a tilted position.

Therefore, depending on the stopping position of the rocker arm 20, the oil level H in the oil reservoir chamber 22 becomes closer to the oil hole 15 as shown in FIG.
It becomes easier to get sucked into 3.

The present invention was devised in view of the above-mentioned problems, and is particularly provided so that the oil reservoir chamber of the hydraulic lash adjuster is oriented horizontally when the valve is opened.

Alternatively, when the oil reservoir is provided so as to be inclined so that the bottom side of the body faces upward when the valve is opened, the oil surface of the oil reservoir is separated from the oil hole.

[Means for solving problems]

Therefore, as shown in FIG. 1, the present invention is provided so that the oil reservoir chamber 22 is oriented horizontally when the valve is opened, or the oil reservoir chamber is provided such that the bottom side of the body thereof faces upward when the valve is opened. Targeting a hydraulic lash adjuster that is installed at an angle, the upper wall of the oil sump chamber 22 near the body bottom 11a is expanded further upward, and the oil level H in the oil sump chamber 22 is expanded upward. The basic feature is that it is located within the cavity l of the chamber.

Here, of the upper wall portion of the oil reservoir chamber 22, especially the body bottom portion 11a.
The reason why the closer portion is expanded upward is to prevent air from accumulating in this portion when the valve is opened and to prevent the oil level H from approaching the oil hole 15.

[Effect]

By arranging the oil level H in the oil reservoir chamber 22 to be within the space 1, the oil level I-I is always maintained apart from the oil hole 15. Therefore, not only when the engine is running, but also when the engine is restarted after being stopped with the valve open, air is not mixed into the oil sucked into the high-pressure chamber.

〔Example〕

FIG. 2 is an enlarged sectional view showing a center pivot rocker arm 20 attached as a valve operating mechanism of a horizontally opposed engine and a hydraulic lash adjuster according to an embodiment of the present invention attached to the center pivot rocker arm 20. In the figure, 20a is a rocker shaft, and 23 is an oil guide path that leads oil from the rocker shaft 20a to the hydraulic lash adjuster.

The hydraulic lash adjuster of this embodiment is fitted into a lash adjuster support hole 21 bored at the end of a rocker arm 20, and includes a bottomed hollow cylindrical body 11 having an oil hole 15 at the bottom 11a, A plunger 12 is slidably fitted into the body 11 and forms a high pressure chamber 13 between it and the bottom 11a; The plunger spring 14 and the oil hole 15 also provided in the high pressure chamber 13
It has a check valve 16 that controls the opening and closing of the valve, and a check valve cage 17 that holds the check valve 16. Also, the lash adjuster support hole 2 of the rocker arm 20
1, there is an oil reservoir chamber 2 adjacent to the body bottom 11a.
2 is provided. Oil is supplied into this oil reservoir chamber 22 from an oil guide path 23 of the rocker arm 20.

As mentioned above, since this hydraulic lash adjuster is provided as a control mechanism for a horizontally opposed engine, the plunger 12. The body 11 and the oil reservoir chamber 22 are oriented in the horizontal direction when the valve is closed and the rocker arm 20 is stopped, and are oriented in the horizontal direction when the valve is open and the rocker arm 20 is at rest.
When it is stopped, it is tilted slightly upwards (that is, it is tilted so that the bottom side of the body of the oil reservoir chamber 22 faces upward).

Furthermore, due to the rocking of the rocker arm 20, the oil level H in the oil reservoir chamber 22 apparently changes its position, and the rocker arm 2
In order to prevent the oil level H from approaching the oil hole 15 when the oil stops at an arbitrary position, the upper wall portion of the oil reservoir chamber 22, including the portion near the body bottom 11a, is extended obliquely upward from the oil reservoir chamber 22. It is further expanded in the direction of the oil guide path 23 that is coming out, so that the oil level H comes into the gap 10a of the oil reservoir chamber 22 that is expanded in the direction of the oil guide path 23. In this embodiment, an air vent hole 24 is provided which extends from the tip side of this gap 10a of the oil reservoir chamber 22 and opens outward from the rocker arm 20, so that the air accumulated on the oil surface H can be released to the outside. I have to.

Further, a hole 25 opening diagonally downward in the lower part of the rocker arm 20 is provided when forming the gap 10a of the oil reservoir chamber 22, and after forming, a ball 25a is press-fitted to close the hole 25. .

These valve mechanisms operate as follows during engine operation. That is, the rocker arm 20 is connected to the rocker shaft 20a.
The rear end of the valve 30 is pushed by the oil level type lash adjuster of this embodiment during engine intake and exhaust.
Open and close it.

When the pulp valve 30 is opened, the rocker arm 20 rotates counterclockwise in the figure, and the plunger 12 slides inward of the body 11 by the force of the valve spring 31. At this time check valve 1
6 closes the oil hole 15, the oil trapped in the high pressure chamber 13 becomes rigid, and the plunger 12 then moves together with the rocker arm 20 to push out the valve 30. On the contrary, when the valve is closed, the rocker arm 20 rotates clockwise,
The force of the valve spring ceases to act, and the plunger 12, which had been contracted until then, is caused to slide toward the open end of the body 11. At this time, if the amount of oil in the high pressure chamber 13 is insufficient, negative pressure is generated as the plunger 12 slides, causing the check valve 16 to move away from the oil hole and suck oil from the oil reservoir chamber 22. Become. In order to keep the amount of oil in the oil reservoir chamber 22 constant during engine operation, oil flowing from the rocker shaft 20a through the oil guide path 23 enters the oil reservoir chamber 22 through the gap 10a. Further, the air separated from the oil and accumulated in the void 10a is discharged to the outside through the air vent hole 24.

On the other hand, even if the rocker arm 20 stops at an arbitrary position, the oil level H remains within the gap 10a of the oil reservoir chamber 22, and the oil hole 1
5, so when oil is sucked into the high pressure chamber 13, especially when the engine stops with the valve 30 open, oil is sucked into the high pressure chamber 13 when the engine is restarted. At the same time, air is not mixed into the oil, and the rigidity of the oil in the high pressure chamber 13 does not decrease.

3 to 7 show another embodiment of the present invention, in which FIG. 3 shows the earth wall section of the oil sump chamber 22 in a direction perpendicular to the direction in which the oil sump chamber 22 is drilled. It is expanded to form a gap tab. FIG. 4 shows that the oil reservoir chamber 22 is connected to the rocker arm 2.
The opening extends to the outer surface, and the opening is closed by caulking and press-fitting the sealing plate 26. Also, FIGS. 5 to 7 show the oil sump chamber 22.
The opening extends to the outer surface of the rocker arm 20, but in both cases, the opening is closed using an oil chamber 27, and the oil reservoir chamber 22 is substantially constituted by the hollow part of the oil chamber 27. It is something that will be done. The other configurations are the same as those of the previous embodiment, and the same components are given the same numbers.

〔Effect of the invention〕

According to the hydraulic lash adjuster of the present invention described in detail above, the oil reservoir is provided so as to be oriented horizontally when the valve is opened, or the oil reservoir chamber is oriented upward when the valve is opened. With a conventional oil sump chamber structure, even if the rocker arm rotates and the oil level approaches the oil hole, the upper wall of the oil sump chamber cannot be moved further upwards. Since the oil level in the oil reservoir chamber is expanded upward, the oil level is always kept away from the oil hole, especially when the engine is restarted. It is possible to accurately prevent air from getting mixed into the oil due to insufficient oil level height, which often occurs when oil is sucked into a high-pressure chamber. Therefore, it is possible to effectively prevent problems such as deterioration of startability when starting the engine, generation of start noise, and progression of wear in various parts of the valve mechanism, which are further caused by a decrease in the stiffness of the oil due to air entrainment.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view showing the basic configuration of the present invention, FIG. 2 is an explanatory diagram of a valve train mechanism showing a hydraulic lash adjuster according to an embodiment of the present invention, and FIG. 3 is another embodiment of the present invention. FIG. 4 is an explanatory diagram showing a hydraulic lash adjuster according to another embodiment of the present invention, and FIG. 5 is an explanatory diagram showing a hydraulic lash adjuster according to another embodiment of the present invention. An explanatory diagram showing a hydraulic lash adjuster, FIG. 6 is an explanatory diagram of a lash adjuster according to another embodiment of the invention, and FIG. 7 is an explanatory diagram of a hydraulic lash adjuster according to another embodiment of the invention. FIG. 8 is a partial sectional view showing a conventional valve operating mechanism, and FIG. 9 is an enlarged sectional view showing the valve operating mechanism used as it is in a horizontally opposed engine, a V-engine, etc. In the figure, 1, 10a, lob are voids, 11 is body, lla
is the bottom of the body, 12 is the plunger, 13 is the high pressure chamber, 14
15 is an elastic body, 15 is an oil hole, 16 is a check valve, 17 is a check valve cage, 20 is a rocker arm, 22 is an oil reservoir chamber, and 23 is an oil guide path. Figure Figure Figure Figure Figure

Claims (1)

[Claims] A hollow cylindrical body with a bottom that is attached to the rocker arm and has an oil hole at the bottom; a plunger that is slidably fitted into the body and forms a high pressure chamber between the body and the bottom; an elastic body mounted therein to bias the plunger toward the open end of the body; a check valve also provided in the high pressure chamber for controlling opening and closing of the oil hole; a check valve cage holding the check valve; and adjacent to the bottom of the body. and an oil reservoir chamber provided in the rocker arm, and the oil reservoir chamber is provided so that it is oriented horizontally when the valve is opened, or so that the bottom side of the body is oriented upward when the valve is opened. In a hydraulic lash adjuster that is installed at an angle and supplies oil from a rocker arm into an oil reservoir chamber through an oil guide path, the upper wall of the oil reservoir chamber near the bottom of the body is further expanded upward, and the oil reservoir chamber is expanded upwardly. A hydraulic lash adjuster characterized in that the oil level is located within a gap in an oil reservoir chamber that expands upward.