JPS6359008B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic lifter for an internal combustion engine, and more specifically, the present invention relates to a hydraulic lifter for an internal combustion engine, and more specifically, a lifter body having a cylinder portion therein, and a lifter body that is slidably inserted into the cylinder portion of the lifter body and is inserted into the cylinder portion. A plunger forming a hydraulic oil chamber, a supply hole for supplying pressure oil to the hydraulic oil chamber, and a check ball and a coil spring arranged in the hydraulic oil chamber, and a check ball and a coil spring arranged in series with the supply hole to supply the same. comprising a check valve that substantially only allows pressure oil to flow into the hydraulic oil chamber from the hole;
The internal combustion engine is configured such that the contact surface of the head comes into contact with a cam rotating via a power transmission mechanism, and the intake and exhaust valves are opened and closed by the action of the cam via the lifter body, the hydraulic pressure in the hydraulic oil chamber, and the plunger. Concerning improvements to hydraulic lifters for engines.

Generally, in this type of hydraulic lifter, lubricating oil from the internal combustion engine flows into the hydraulic lifter, and this oil pressure automatically eliminates valve clearance regardless of the cold temperature of the internal combustion engine or the wear of the contact parts in the valve opening/closing mechanism. , the action of the cam is directly transmitted to the intake and exhaust valves to open and close them. Therefore, this type of hydraulic lifter always maintains the normal opening/closing timing of the intake and exhaust valves, prevents the generation of noise from the valve opening/closing mechanism, and also functions to suppress wear on each contact part in the valve opening/closing mechanism. do. By the way, this type of hydraulic lifter uses pressure oil from a lubricating hydraulic pump installed in the internal combustion engine body, or it uses a separate hydraulic source and hydraulic pump to supply oil from this hydraulic pump. It uses pressure oil. For this reason, conventional hydraulic lifters always require a hydraulic pump and a pressure oil supply passage from the hydraulic pump.

The present invention has been made focusing on this point,
The main purpose is to provide a hydraulic lifter with a simple structure and low cost by omitting the conventionally required hydraulic pump and pressure oil supply passage.

The present invention will be described below with reference to the drawings. FIG. 1 shows an opening/closing mechanism for intake and exhaust valves employing a hydraulic lifter according to the present invention. This valve opening/closing mechanism is employed in a four-stroke motorcycle engine 10 of an overhead camshaft type, and is disposed above a cylinder head 11 and covered with a head cover 12. The valve opening/closing mechanism includes a cam 21 rotated by the engine 10 via a power transmission mechanism, a hydraulic lifter 30 according to the present invention that is slidably fitted into an assembly hole 11a at the top of the cylinder head 11, and an assembly. The valve spring 22 is inserted into the hole 11a. As a result, in the valve opening/closing mechanism, when the cam 21 rotates due to the drive of the engine 10, the action of the cam 21 is transmitted to the intake valve 13 and the exhaust valve 14 via the hydraulic lifter 30.
The intake and exhaust valves 1 are pressed against the valve spring 22.
3 and 14 alternately move up and down to alternately open and close the intake port 11b and the exhaust port 11c.

As shown in an enlarged view in FIG. 2, the hydraulic lifter 30 includes a cylindrical head-shaped lifter body 31 that is slidably inserted into an assembly hole 11a of the cylinder head 11.
, a cylinder 32 assembled into a cylindrical portion 31a concentrically protruding inside the lifter main body 31, and a plunger 3 slidably inserted into the cylinder 32.
3, a check valve 34 and a coil spring 37 disposed within the plunger 33. The cylinder 32 includes a partition plate portion 32a therein, and forms an upper hydraulic chamber _R1 within the cylindrical portion 31a. Further, the plunger 33 is formed in a cylindrical shape with a bottom.
A lower oil chamber R 2 is formed in the lower part of the oil chamber ₂ and communicates with the upper oil chamber R ₁ via a through hole 32 b provided approximately at the center of the starting plate portion 32 a. This plunger 33 is
Stopper 32c provided inside the lower end of the cylinder 32
A check ball 34 is disposed within the plunger 33, and the tips of the intake and exhaust valves 13 and 14 are in contact with the lower surface of the plunger 33. The check ball 34 is elastically supported by a small-diameter coil spring 37 interposed in a retainer 36 supported by a large-diameter coil spring 35, and is mounted on a valve seat portion provided at the lower opening edge of the through hole 32b. is in contact with. Thus, when clearance occurs between the cam 21 and the lifter main body 31 and between the plunger 33 and the intake and exhaust valves 13 and 14,
Large diameter coil spring 35 inside plunger 33
The lifter main body 31 and the plunger 33 are made to slide relative to each other by extending the clearance so that the clearance is always 0, and the check ball 34 is passed through the space created in the lower oil chamber _{R2 and} the upper oil chamber is opened.
Pressure oil is replenished from _R1 .

A supply hole 31b communicating with the upper oil chamber _R1 is formed approximately at the center of the surface of the lifter main body 31 that contacts the cam 21, which is formed in the head portion of the lifter body 31. The hole center of this through hole 31b is slightly eccentric (l in the figure) to the right in the figure with respect to the rotation center 21a of the cam 21 which rotates clockwise (arrow in the figure). As a result, the outer end of the supply hole 31b is located at the rotation center 2 of the cam 21.
It is opened at a position slightly offset from the contact surface of the lifter main body 31 in the counter-rotation direction of the cam 21 with respect to 1a. The check valve is connected to this supply hole 31b.
from the supply hole 31b to the lower oil chamber.
Substantially, only the lubricating oil is allowed to flow into _R2 .

In the hydraulic lifter 30 configured in this manner, the lubricating oil that is splashed and attached to the surface of the cam 21 and the contact surface of the head of the lifter body 31 is transferred to the cam 2.
As the lifter body 31 rotates, the lifter body 31 is drawn into the wedge-shaped space S on the right side of the drawing formed between the surface of the cam 21 and the contact surface of the head of the lifter body 31 due to viscosity. This wedge-shaped space S forms a tapered flow path that gradually reduces to the opening at the outer end of the supply hole 31b of the lifter main body 31, so that the lubricating oil drawn into the wedge-shaped space S flows under the pressure This generates pressurized oil and is supplied into the upper oil chamber _R1 of the lifter main body 31, and then into the lower oil chamber _R2 via the check valve. Therefore,
In the hydraulic lifter 30, unlike conventional hydraulic lifters of this type, there is no need to use pressure oil from a hydraulic pump, and the hydraulic pump for the hydraulic lifter can be omitted, and the hydraulic pump or lubricating oil A pressure oil supply passage from the hydraulic pump to the hydraulic lifter can be omitted.

In this embodiment, the upper and lower oil chambers R ₁ and R ₂ of the hydraulic lifter 30 are formed by the lifter body 31, the cylinder 32, and the plunger 33. It may be formed by a suitably shaped lifter body and a plunger. In short, the present invention provides a lifter body having a cylinder portion therein, a plunger that is slidably fitted into the cylinder portion of the lifter body and forms a hydraulic oil chamber in the cylinder portion, and a plunger that forms a hydraulic oil chamber in the cylinder portion. It consists of a supply hole for supplying oil, a check ball and a coil spring arranged in the hydraulic oil chamber, and is provided in series with the supply hole to only allow pressure oil to flow into the hydraulic oil chamber from the supply hole. The contact surface of the head comes into contact with a cam that rotates via a power transmission mechanism, and the lifter body, the hydraulic pressure in the hydraulic oil chamber, and the action of the cam via the plunger The invention can be implemented in various hydraulic lifters for internal combustion engines that open and close intake and exhaust valves.

As is clear from the above description, in the present invention, in the various hydraulic lifters, the outer end of the supply hole is slightly moved in the counter-rotation direction of the cam at the contact surface with respect to the rotation center of the cam. Its structural feature lies in the fact that it opens only at deviated positions. Therefore, according to the present invention, the shape and function originally possessed by the opening/closing cams of intake and exhaust valves are effectively utilized to generate pressure oil for the hydraulic lifter and to direct this pressure oil into the hydraulic lifter. This makes it possible to omit a hydraulic pump and eliminates the need for a pressure oil supply passage from the hydraulic pump to the hydraulic lifter.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an example of a valve opening/closing mechanism employing a hydraulic lifter according to the present invention, and FIG. 2 is an enlarged longitudinal sectional view of the hydraulic lifter shown in FIG. 1. Explanation of symbols, 10... Engine, 11... Cylinder head, 13... Intake valve, 14... Exhaust valve, 21... Cam, 22... Valve spring, 30... Hydraulic lifter, 31... Lifter body,
31b... Supply hole, 32... Cylinder, 33...
Plunger, 34...Check ball, 37...
Coil spring, R ₂ ... Hydraulic oil chamber (lower oil chamber).

Claims (1)

[Claims] 1. A lifter body having a cylinder portion therein, a plunger that is slidably fitted into the cylinder portion of the lifter body to form a hydraulic oil chamber within the cylinder portion, and a supply supplying pressure oil to the hydraulic oil chamber. A reverse valve is provided in series with the supply hole and substantially only allows pressure oil to flow into the hydraulic oil chamber from the supply hole, and is comprised of a check ball and a coil spring disposed in the hydraulic oil chamber. Equipped with a stop valve, the contact surface of the head comes into contact with a cam that rotates via a power transmission mechanism, and the intake and exhaust valves are opened and closed by the action of the cam via the lifter body, the hydraulic pressure in the hydraulic oil chamber, and the plunger. In the hydraulic lifter for an internal combustion engine, the outer end of the supply hole is opened only at a position slightly offset in the counter-rotation direction of the cam on the contact surface with respect to the rotation center of the cam. Hydraulic lifter featuring: