US20080083386A1

US20080083386A1 - Variable valve lift follower for vehicle

Info

Publication number: US20080083386A1
Application number: US11/648,876
Authority: US
Inventors: Chung Han Oh
Original assignee: Hyundai Motor Co
Current assignee: Hyundai Motor Co
Priority date: 2006-10-10
Filing date: 2006-12-29
Publication date: 2008-04-10
Also published as: KR100867842B1; CN101161995B; KR20080032726A; CN101161995A; DE102007011834A1

Abstract

A variable valve lift follower for a vehicle includes an outer body receiving a rotational force from a high lift cam; an inner body with a first end portion hinge-connected with the outer body, receiving a rotational force from a low lift cam; a hydraulic lash adjuster (HLA) contact portion for supplying oil to the first end portion of the inner body; a valve contact portion on a second end of the inner body; and a knock pin on the top of the valve contact portion, connecting the outer body to the inner body during high lift.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2006-0098272, filed on Oct. 10, 2006, the entire disclosure of which is hereby incorporated by reference.

BACKGOUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a variable valve lift follower for a vehicle and, more particularly, to a variable valve lift follower for a vehicle having a knock pin in a valve contact portion.
2. Description of Related Art
In general, since the rotational speed of internal combustion engines varies from about 500 rpm to 6,000 rpm, the flow of air taken in the engine varies considerably. In a reciprocating internal combustion engine that controls the flow quantities of the air and exhaust gas by opening and closing intake valves and exhaust valves, to obtain high power when driving at high speed, it is necessary to increase the charge efficiency by prolonging the time that the intake valves are open which makes the overlap with the exhaust valves larger and thereby the rotational state of the engine becomes bad when driving at low speed. Accordingly, it is necessary to keep the overlap within a predetermined range.
Variable valve lift systems have been used to improve the output performance of the engine by adjusting the opening and closing timings of the intake valves and the exhaust valves with various operating conditions of the engine.
A valve contact portion is established on the bottom of one side of the inner body of the variable valve lift follower and a hydraulic lash adjuster (HLA) contact portion is provided on the other side.
A lock plate body and a lock plate connected with each other are mounted on one end of an inner body.
One end portion of the lock plate body is connected with the lock plate and the other end portion of the lock plate body comes in contact with the piston.
Since the lock system, such as lock plate and the like, is positioned on the HLA side, the other parts of the variable valve lift are concentrated in the valve contact portion. Accordingly, the effective mass of the follower adds an inertia mass to the valves' motion, thus influencing the dynamic behavior of the valve train.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

The present invention provides a variable valve lift follower for a vehicle, comprising: an outer body receiving a rotational force from a high lift cam; an inner body, one end portion of which is hinge-connected with the outer body, receiving a rotational force from a low lift cam; a hydraulic lash adjuster (HLA) contact portion to supply oil to the end portion of the inner body; a valve contact portion on the other end of the inner body; and a knock pin, installed on the top of the valve contact portion, connecting the outer body with the inner body during high lift.
In an exemplary embodiment, the variable valve lift follower further comprises an oil path connecting the HLA contact portion with the knock pin to transmit oil pressure from the HLA contact portion to the knock pin.
In a further exemplary embodiment, the oil path includes a first connection path connected with the HLA contact portion, a second connection path formed in the horizontal direction with the first connection path, and a third connection path that transmits the oil pressure from the second connection path to the knock pin, the first and third connection path being inclined.
An oil supply hole may further be provided on an end of the second connection path and a cap may be attached detachably on the oil supply hole.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view depicting a variable valve lift system according to an embodiment of the present invention;

FIG. 2 is a perspective view illustrating a variable valve lift follower in accordance with an embodiment of the present invention;

FIG. 3 is a perspective view illustrating an inner body in accordance with an embodiment of the present invention; and

FIG. 4 is a bottom view of FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.
In some embodiments, a variable valve lift follower includes three cams for each valve to control the opening amounts of the valve based on engine conditions by the rotational force of a cam assembly. A middle low lift cam 10 and two high lift cams 11 are disposed in a row.
A knock pin, formed on the top of the valve contact portion 51 positioned opposite to the HLA 23, moves in the longitudinal direction to connect an inner body 54 and an outer body 55 with each other, thus applying a high lift thereto.
An HLA contact portion 50 supplying oil to the inner body 54 is provided on the bottom of one side of the inner body 54, a valve contact portion 51 is provided on the bottom of the other side of the inner body 54, and the knock pin is installed on the top of the valve contact portion 51.
The knock pin is installed on the other end of the inner body 54 so as to move in the forward and backward directions (based on the longitudinal direction of the outer body) by the oil pressure, and a hinge pin 56 is disposed on one end of the inner body 54, through which the outer body 55 and the end portion of the inner body 54 are hinge-connected with each other, thus allowing the other end portion of the outer body 55 to rotate independently.
Since the knock pin is moved by the oil pressure, the oil path 52 is provided to connect the HLA contact portion 50 with a cylinder 53 including the knock pin, thus supplying oil introduced through the HLA contact portion 50 to the knock pin.
The oil path 52 comprises a first connection path 52 a connected with the HLA contact portion 50, a second connection path 52 b formed in the horizontal direction and fluidly connected to the first connection path 52 a, and a third connection path 52 c coupling the second connection path 52 b to the cylinder 53.
The first and third connection paths 52 a and 52 c are inclined. The paths 52 a and 52 c can be inclined at various angles to avoid interference with peripheral parts. An oil supply hole 57 extending to the outside is disposed on an end of the second connection path 52 b and a cap is attached detachably onto the oil supply hole 57.
Operation of the variable valve lift follower in accordance with an embodiment of the present invention will now be described.
(1) When applying high lift: the oil is introduced to the inner body 54 through the HLA contact portion 50 in the period of high speed of full load, supplied from the HLA contact portion 50 to the first connection path 52 a of the oil path, and moved to the second and third connection path 52 b and 52 c, thus transmitting the oil pressure to the knock pin in the cylinder 53.
Subsequently, the knock pin is pushed out from the inner body 54 by the oil pressure and the rotational forces of the high lift cams 11 are transmitted to the knock pin when the other end portion rotates downward, thus becoming in a high lift state.
(2) When applying low lift: as the oil charged in the cylinder is exhausted in the period of low speed of part load, the knock pin is returned to the inside of the inner body 54 and, as the oil moves from the oil path 52 to the HLA contact portion 50 and is discharged to the HLA 23, the outer body 55 and the inner body 54 are separated from each other to rotate independently. The valve is operated only by the inner body 54, thus becoming in a low lift state.
The present invention can reduce stress and friction caught by the valve spring to enhance the fuel efficiency and the engine performance by providing a knock pin connecting the outer body 55 with the inner body 54 on the top of the valve contact portion. The oil path 52, through which the oil is received from the HLA 23 transmits the oil pressure to the knock pin.
As described above, according the variable valve lift follower in accordance with the present invention, it is possible to reduce the effective mass of the valves and decrease the stress and friction on the valve spring, thus enhancing the fuel efficiency and the engine performance, by providing the knock pin connecting the outer body with the inner body on the top of the valve contact portion and by forming the oil path, through which the oil is received from the HLA and the oil pressure is transmitted to the knock pin.
While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A variable valve lift follower for a vehicle, comprising:

an outer body configured to receive a rotational force from a high lift cam;

an inner body comprising a first end portion hinge-connected with the outer body, configured to receive a rotational force from a low lift cam;

a hydraulic lash adjuster (HLA) contact portion configured to supply oil to the first end portion of the inner body;

a valve contact portion disposed on a second end of the inner body; and

a knock pin, disposed on a top of the valve contact portion, configured to connect the outer body to the inner body during a high lift.

2. The variable valve lift follower as recited in claim 1, further comprising an oil path fluidly connecting the HLA contact portion with the knock pin.

3. The variable valve lift follower as recited in claim 2, wherein the oil path comprises a first connection path connected to the HLA contact portion, a second connection path connected to the first connection path, and a third connection path connecting the second connection path to the knock pin, wherein the first and third connection paths are inclined and the second connection path is substantially horizontal.

4. The variable valve lift follower as recited in claim 3, further comprising an oil supply hole on an end of the second connection path, and a cap attached detachably onto the oil supply hole.