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Patent 2541726 Summary

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Claims and Abstract availability

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(12) Patent Application: (11) CA 2541726
(54) English Title: OSCILLATING CAM AND DYNAMIC VALVE MECHANISM OF INTERNAL COMBUSTION ENGINE
(54) French Title: CAME OSCILLANTE ET MECANISME A SOUPAPE DYNAMIQUE DE MOTEUR A COMBUSTION INTERNE
Status: Deemed Abandoned and Beyond the Period of Reinstatement - Pending Response to Notice of Disregarded Communication
Bibliographic Data
(51) International Patent Classification (IPC):
  • F01L 01/08 (2006.01)
  • F01L 13/00 (2006.01)
(72) Inventors :
  • FUJITA, HIDEO (Japan)
  • HATAMURA, KOICHI (Japan)
(73) Owners :
  • YAMAHA HATSUDOKI KABUSHIKI KAISHA
(71) Applicants :
  • YAMAHA HATSUDOKI KABUSHIKI KAISHA (Japan)
(74) Agent: BARRIGAR INTELLECTUAL PROPERTY LAW
(74) Associate agent:
(45) Issued:
(86) PCT Filing Date: 2004-08-25
(87) Open to Public Inspection: 2006-03-02
Examination requested: 2009-01-08
Availability of licence: N/A
Dedicated to the Public: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/JP2004/012193
(87) International Publication Number: JP2004012193
(85) National Entry: 2006-02-27

(30) Application Priority Data: None

Abstracts

English Abstract


An oscillating cam provided with a cam face having a base circle part and a
lift part and disposed to perform reciprocating operation in which the contact
surface of the a base circle part is formed narrower than the contact surface
of the lift part.


French Abstract

La présente invention concerne une came oscillante disposant d'une base circulaire et d'un élément de levage, et disposée de manière à réaliser une opération de va-et-vient ; et au sein de laquelle la surface de contact de la base circulaire est plus étroite que la surface de contact de l~élément de levage.

Claims

Note: Claims are shown in the official language in which they were submitted.


CLAIMS
[Claim 1] A rocking cam comprising a cam surface having a base circle
portion and a lift portion, and disposed so as to make reciprocating
motion,
wherein a width of a contact surface of the base circle portion
is formed smaller than a width of a contact surface of the lift portion.
[Claim 2] A valve mechanism for an internal combustion engine,
having: a camshaft rotated by a crankshaft of the internal combustion
engine; a rotating cam provided to the camshaft; a rocking shaft
provided in parallel to the camshaft; and a rocking cam supported
with the rocking shaft and freely rockable by the rotating cam, and
capable of varying a lift amount of an intake valve or an exhaust
valve of the internal combustion engine, wherein the rocking cam
includes a cam surface having a base circle portion and a lift portion,
and is disposed so as to make reciprocating motion; and
a width of a contact surface of the base circle portion is formed
smaller than a width of a contact surface of the lift portion.
[Claim 3] The valve mechanism for an internal combustion engine
according to Claim 2,
wherein the rocking cam is provided with a movable rotating cam
abutment portion that comes into contact with the rotating cam to
transmit a drive force from the rotating cam to the rocking cam, and
provided with a guide portion for guiding the rotating cam abutment
portion in a certain direction; the drive force from the rotating
cam is inputted to the guide portion via the rotating cam abutment
portion so that the rocking cam is rocked;
a variable abutment portion mechanism is provided for making a
relative distance between the rotating cam abutment portion and a
center axis of the rocking shaft variable by making the rotating cam
abutment portion movable along the guide portion; and a lift amount
of each valve is made variable by thus making the relative distance
variable.

Description

Note: Descriptions are shown in the official language in which they were submitted.


CA 02541726 2006-02-27
Specification
ROCKING CAM AND VALVE MECHANISM FOR AN INTERNAL COMBUSTION ENGINE
Technical Field
[0001]
The present invention relates to a rocking cam, which includes a
cam surface having a base circle portion and a lift portion, and which
is disposed so as to make reciprocating motion, and relates to a valve
mechanism for an internal combustion engine, which is provided with
the rocking cam.
Related Art
[0002]
Conventionally, this type of valve mechanism for an internal
combustion engine has: a camshaft rotated by a crankshaft; a rotating
cam provided to the camshaft; a rocking cam rocked by the rotating
cam for reciprocating motion; and a rocker arm partly coming into
contact with a cam surface of the rocking cam. When the rocking cam
is rocked, the cam surface thereof allows the rocker arm to be rocked.
This motion by the rocker arm presses an intake or exhaust valve to
open/close the valve (See Patent Document 1).
Patent Document 1: JP-A-H7-063023
Disclosure of the Invention
Problem to be Solved by the Invention
[0003]
However, in such a conventional valve mechanism that the cam surface
of the rocking cam has a base circle portion, a lift portion and a
ramp portion for connecting therebetween, the cam surface requires
a certain width to secure strength enough to withstand a large force
acting on the cam surface. This results in an increase in weight
of the rocking cam on its distal end side, causing an increase in
inertia force of the rocking cam which makes reciprocating motion.
Accordingly, other parts associated with the rocking cam also need
to secure certain strength, causing increases in weight of the parts
as well as in size of the entire system. This creates additional
problem with an increase in wear and the like on a contact portion
1

CA 02541726 2006-02-27
of the rocking cam.
[0004]
In the view of the above, the present invention has been made in
order to solve the above-mentioned problems of the prior art.
Accordingly, it is an object of the present invention to provide a
rocking cam and a valve mechanism for an internal combustion engine,
which can achieve reductions in size and weight as well as in wear
and the like on a contact portion of the rocking cam.
Means for Solving the Problem
[0005]
In order to attain the above object, the invention as described in
Claim 1 provides a rocking cam including a cam surface having a base
circle portion and a lift portion, and disposed so as to make
reciprocating motion, in which a width of a contact surface of the
base circle portion is formed smaller than a width of a contact surface
of the lift portion.
[0006]
The invention as described in Claim 2 provides a valve mechanism
for an internal combustion engine, having: a camshaft rotated by a
crankshaft of the internal combustion engine; a rotating cam provided
to the camshaft; a rocking shaft provided in parallel to the camshaft;
and a rocking cam supported with the rocking shaft and freely rockable
by the rotating cam and capable of varying a lift amount of an intake
valve or an exhaust valve of the internal combustion engine, in which
the rocking cam includes a cam surface having a base circle portion
and a lift portion, and is disposed so as to make reciprocating motion,
and a width of a contact surface of the base circle portion is formed
smaller than a width of a contact surface of the lift portion.
[0007]
The invention as described in Claim 3 provides the valve mechanism
for an internal combustion engine according to Claim 2, in which the
rocking cam is provided with a movable rotating cam abutment portion
that comes into contact with the rotating cam to transmit a drive
force from the rotating cam to the rocking cam, and provided with
a guide portion for guiding the rotating cam abutment portion in a
certain direction; the drive force from the rotating cam is inputted
2

CA 02541726 2006-02-27
to the guide portion via the rotating cam abutment portion so that
the rocking cam is rocked; a variable abutment portion mechanism is
provided for making a relative distance between the rotating cam
abutment portion and a center axis of the rocking shaft variable by
making the rotating cam abutment portion movable along the guide
portion; and a lift amount of each valve is made variable by thus
making the relative distance variable.
Effect of the Invention
[0008]
According to the invention as described in Claim 1, the rocking cam
includes the cam surface having the base circle portion and the lift
portion, and is disposed so as to make reciprocating motion, in which
the width of the contact surface of the base circle portion is formed
smaller than the width of the contact surface of the lift portion.
Therefore, weight of the rocking cam can be reduced. This results
in a reduction in inertia force of the rocking cam at the time of
rocking movement, as well as in a reduction in weight of parts
associated with the rocking cam.
[0009]
According to the invention as described in Claims 2 and 3, the valve
mechanism for an internal combustion engine, which is capable of
changing the lift amount of the intake valve or the exhaust valve
of the internal combustion engine, is provided with the rocking cam
having the base circle portion and the lift portion, with the width
of the contact surface of the base circle portion being formed smaller
than the width of the contact surface of the lift portion. This allows
this variable valve mechanism to provide the above-mentionedeffects.
Brief Description of the Drawings
[0010]
FIG. 1 is a longitudinal sectional view of the main portion of the
variable valve mechanismfor the internal combustion engine according
to Embodiment 1 of the present invention when the maximum lift amount
is required, illustrating the state in which the intake valve is
closed.
FIG. 2 is a longitudinal sectional view of the main portion of the
variable valve mechanismfor the internal combustion engine according
3

CA 02541726 2006-02-27
to Embodiment 1 of the present invention when the maximum lift amount
is required, illustrating the state in which the intake valve is open.
FIG. 3 is a longitudinal sectional view of the main portion of the
variable valve mechanismforthe internal combustion engine according
to Embodiment 1 of the present invention when the minimum lift amount
is required, illustrating the state in which the intake valve is
closed.
FIG. 4 is a longitudinal sectional view of the main portion of the
variable valve mechanismforthe internal combustion engine according
to Embodiment 1 of the present invention when the minimum lift amount
is required, illustrating the state in which the intake valve is open.
FIGS. 5(a) and 5(b) are views showing a rocking cam according to
Embodiment 1 of the present invention, of which FIG. 5 (a) is a front
view, and FIG. 5(b) is a bottom view.
FIG. 6 is a longitudinal sectional view of the main portion of the
variable valve mechanismfor the internal combustion engine according
to Embodiment 2 of the present invention when the maximum lift amount
is required, illustrating the state in which the intake valve is
closed.
FIG. 7 is a longitudinal sectional view of the main portion of the
variable valve mechanismforthe internal combustion engine according
to Embodiment 2 of the present invention when the minimum lift amount
is required, illustrating the state in which the intake valve is
closed.
FIGS. 8(a) and 8(b) are views showing a rocking cam according to
Embodiment 2 of the present invention, of which FIG. 8 (a) is a front
view, and FIG. 8(b) is a bottom view.
FIG. 9 is a longitudinal sectional view of the main portion of the
variable valve mechanismfor the internal combustion engine according
to Embodiment 3 of the present invention when the maximum lift amount
is required, illustrating the state in which the intake valve is
closed.
FIGs. 10(a) and 10(b) are views showing a rocking cam according to
Embodiment 3 of the present invention, of which FIG. 10 (a) is a front
view, and FIG. 10(b) is a bottom view.
FIG. 11 is a perspective view of a rocking cam according to Embodiment
4

CA 02541726 2006-02-27
3, viewed obliquely from below.
FIG. 12 is a longitudinal sectional view of the main portion of
variable valve mechanism for an internal combustion engine according
to Embodiment 4 of the present invention, illustrating a state in
which the intake valve is closed.
FIGS. 13(a) and 13(b) are views showing a rocking cam according to
Embodiment 4 of the present invention, of which FIG. 13 (a) is a front
view, and FIG. 13(b) is a bottom view.
FIG. 14 is a longitudinal sectional view of the main portion of
variable valve mechanism for an internal combustion engine according
to Embodiment 5 of the present invention, illustrating a state in
which the intake valve is closed.
FIGS. 15(a) and 15(b) are views showing a rocking cam according to
Embodiment 5 of the present invention, of which FIG. 15 (a) is a front
view, and FIG. 15(b) is a bottom view.
Best Mode for Carrying Out the Invention
[0011]
Hereinafter, embodiments of the present invention will be described
with reference to the drawings.
[Embodiment 1 of the Invention]
[0012]
FIGs. 1 through 5 illustrate Embodiment 1 of the present invention.
[0013]
First, the construction will be described. In FIG. l, reference
numeral 1 denotes a variable valve mechanism for an intake valve 11
of an internal combustion gasoline engine. The variable valve
mechanism 1 has a camshaft 2 rotated by a crankshaft (not shown) of
the internal combustion engine, a rotating cam 3 provided to the
camshaft 2, a rocking shaft 4 provided in parallel to the camshaft
2, a rocking cam 5 supported on the rocking shaft 4 and adapted to
rock by the rotating cam 3, and a rocker arm 6 that is rocked in
synchronization with the rocking cam 5 to open/close the intake valve
11.
[0014]
It should be noted that the construction of the variable valve
mechanism 1 is the same between the intake valve 11 and exhaust valve

CA 02541726 2006-02-27
of the gasoline engine. Accordingly, Embodiment 1 focuses on the
mechanism on the intake valve 11 side, and the description of the
mechanism on the exhaust valve side is omitted.
[0015]
As shown in FIG. l, the camshaft 2 is arranged with its longitudinal
direction extending toward the front and back (i.e. in the direction
perpendicular to the plane) of FIG. 1. The camshaft 2 is rotated
about a center axis Ol at a half rotational speed of that of the
crankshaft of the internal combustion engine.
[0016]
Further, the rotating cam 3 is fixed onto the outer peripheral
surface of the camshaft 2 and, as shown in FIG. l, the outer peripheral
portion thereof is configured with a base surface 3a that is
arc-shaped in plan view, and a nose surface 3b projecting from the
base surface 3a.
[0017]
Further, a center axis 02 of the rocking shaft 4 is arranged in
parallel to the center axis Ol of the camshaft 2.
[0018]
The rocking cam 5 is in fitting engagement with the outer peripheral
surface of the rocking shaft 4, and is supported so as to be rockable
about the center axis 02 of the rocking shaft 4. A cam surface 5a
for rocking the rocker arm 6 is formed in the lower end portion of
the rocking cam 5.
[0019]
As shown in FIGS. 1 through 5, in the cam surface 5a, there are
formed an arc-shaped base circle portion 5c around the center axis
02, a lift portion 5d for rocking the rocker arm 6, and a ramp portion
5e connecting between the lift portion 5d and the base circle portion
5c.
[0020]
Further, as shown in FIG. 5, a width L1 of a contact surface of
the base circle portion 5c is formed smaller than a width L2 of a
contact surface of the lift portion 5d.
[0021]
Further, a guide portion 5b as an elongate through-hole is formed
6

CA 02541726 2006-02-27
at the longitudinally middle portion of the rocking cam 5. A roller
shaft 7, which has a center axis 03 in parallel to the center axis
02 of a rocking shaft 4, is movably inserted through the guide portion
5b. Provided to the roller shaft 7 is a roller 8 as a "rotating cam
abutting portion" that contacts and operates in synchronization with
a base surface 3a or a nose surface 3b of the rotating cam 3, for
transmitting the drive force from the rotating cam 3 to the rocking
cam 5.
[0022]
Further, the guide portion 5b is formed in the shape of an elongate
hole so as to guide the roller shaft 7 along its longitudinal direction
over a predetermined distance, and the guiding direction at this time
is inclined with respect to the radial direction of the camshaft 2.
[0023]
Further, as shown in FIG. l, the roller 8 is formed in a circular
shape, and is arranged on the outer peripheral surface of the roller
shaft 7 so that the center axis of the roller 8 becomes the same as
the center axis 03 of the roller shaft 7. The outer peripheral surface
of the roller 8 is capable of rolling on the base surface 3a and nose
surface 3b of the rocking cam 3.
[0024]
In such manner, "the rotating cam abutment portion" which abuts
the rotating cam 3 is formed in the shape of a roller to rotate on
the rotating cam 3 face. This reduces loss of the drive force
transmitted from the rotating cam 3 to "the rotating cam abutment
portion."
[0025]
Incidentally, "the rotating cam abutment portion" is the roller
8 which rotates on the rotating cam 3 face, but is not limited to
this. The rotating cam abutment portion may be the one which slides
on the rotating cam 3 face, as long as the drive force from the rotating
cam 3 is transmitted to the rocking cam 5.
[0026]
Further, a spring 15 for urging the rocking cam 5 toward the rotating
cam 3 side is in fitting engagement with the rocking shaft 4. Thus,
the rocking cam 5 is urged toward the rotating cam 3 side by the urging
7

CA 02541726 2006-02-27
force of the spring 15, so that the outer peripheral surface of the
roller 8 is in constant contact with the base surface 3a or nose surface
3b of the rotating cam 3.
[0027]
Furthermore, the variable valve mechanism 1 is provided with "a
variable abutment portion mechanism"formaking the relative distance
between the roller 8 and the center axis 02 of the rocking shaft 4
variable.
[0028]
"The variable abutment portion mechanism" has a drive shaft 9
fixedly provided onto the rocking shaft 4, and an arm 10 whose one
end portion 10a is connected to the roller shaft 7 and whose other
end portion lOb is connected to the drive shaft 9.
[0029]
The drive shaft 9 is provided to the rocking shaft 4 in such a manner
that a center axis 04 thereof is located in parallel and eccentrically
to the center axis 02 of the rocking shaft 4.
[0030]
Further, an actuator (not shown) for rotating the rocking shaft
4 within a predetermined angle range about the center axis 02 is
connected to one end portion of the rocking shaft 4. Connected to
the actuator is control means (not shown) for controlling the angle
of the actuator according to the operational state of the internal
combustion engine.
[0031]
Thus, when the rocking shaft 4 turns by a predetermined angle, the
drive shaft 9 turns by a predetermined angle about the center axis
02 of the rocking shaft 4, whereby the position of the center axis
04 changes relative to the center axis 02 of the rocking shaft 4.
[0032]
The arm 10 is capable of keeping the distance between the center
axis 03 of the roller shaft 7 and the center axis 04 of the drive
shaft 9 constant. A through-hole 10c, with which the roller shaft
7 is fitted, is formed at the one end portion 10a of the arm 10, and
an insertion portion 10d, into which the drive shaft 9 is inserted
and which is partially open, is formed at the other end portion lOb
8

CA 02541726 2006-02-27
thereof. Accordingly, the roller shaft 7 is rotatably fitted with
the through-hole lOc at the one end portion 10a, and the drive shaft
9 is rotatably fitted with the insertion portion lOd at the other
end portion lOb and mounted in place with a pin 16 so as to prevent
dislodging thereof.
[0033]
Thus, when the rocking shaft 4 is rotated by a predetermined angle
by the actuator, the drive shaft 9 provided to the rocking shaft 4
is turned by a predetermined angle about the center axis 02 of the
rocking shaft 4, and the roller shaft 7 is operated in synchronization
with this turning movement through the arm 10. The roller shaft 7
can be thus moved within the guide portion 5b while keeping the
distance between the center axis 03 of the roller shaft 7 and the
center axis 04 of the drive shaft 9 constant with the arm 10, whereby
the relative distance between the center axis 02 of the rocking shaft
4 and the roller 8 can be made variable.
[0034]
Further, the rocker arm 6 is disposed below the rocking cam 5 while
being rockably supported on the rocker arm shaft 12.
[0035]
Although the rocker arm 6 is rockably supported with the rocker
arm shaft 12, the configuration is not limited to this. The rocker
arm 6 may be rockably supported with a spherical pivot, hydraulic
lash adjuster, or the like.
[0036]
Further, a valve pressing portion 6a is formed at the distal end
portion of the rocker arm 6 for pressing on the upper surface of a
shim 23 fitted on an intake valve 11 which will be described later.
[0037]
A roller 14 is rotatably provided to the roller shaft 13, and the
outer peripheral surface of the roller 14 is capable of rolling on
the cam surface 5a of the rocking cam 5.
[0038]
Further, a spring 17 for urging the rocker arm 6 toward the rocking
cam 5 side is in fitting engagement with the rocker arm shaft 12.
Thus, the rocker arm 6 is urged toward the rocking cam 5 side by means
9

CA 02541726 2006-02-27
of the spring 17, so that the outer peripheral surface of the roller
14 is in constant contact with the cam surface 5a of the rocking cam
5.
[0039]
Further, the intake valve 11 pressed by the valve pressing portion
6a is arranged below the valve pressing portion 6a of the rocker arm
6 so as to be vertically movable.
[0040]
The intake valve 11 has a collet 20 and an upper retainer 21 that
are provided in its upper portion. A valve spring 22 is arranged
below the upper retainer 21. The intake valve 11 is urged toward
the rocker arm 6 side by the urging force of the valve spring 22.
Further, the shim 23 is fitted on the upper end portion of the intake
valve 11.
[0041]
Accordingly, the intake valve 11 can be vertically moved by rocking
the rocker arm 6 in synchronization with the rocking motion of the
rocking cam 5. Thus, by making the relative distance between the
center axis 02 of the rocking cam 4 and the roller 8 variable to adjust
the rocking start position of the rocking cam 5, the lift amount and
the maximum lift timing of the intake valve 11 can be adjustEd and
made variable through the rocker arm 6.
[0042]
Operation of the variable valve mechanism 1 constructed as above
will next be described.
[0043]
First, detailed description will be made on the operation of the
variabJ_e valve mechanism 1 for an internal combustion engine when
the maximum lift amount is required, with reference to FIGS. 1 and
2.
[0044]
Here, FIG. 1 is a longitudinal sectional view of the main portion
of variable valve mechanism 1 of the internal combustion engine
according to Embodiment 1 of the present invention when the maximum
lift amount is required, illustrating the state in which the intake
valve 11 is closed. FIG. 2 is a longitudinal sectional view of the

CA 02541726 2006-02-27
main portion of the variable valve mechanism 1 of the internal
combustion engine according to Embodiment 2 of the present invention
when the maximum lift amount is required, illustrating the state in
which the intake valve is open.
[0045]
First, as shown in FIG. l, the roller shaft 7 is moved to the rotating
cam 3-side end portion of the guide portion 5b, thereby changing the
relative distance between the center axis 02 of the rocking shaft
4 and the roller 8. That is, the rocking shaft 4 is turned by a
predetermined angle by the actuator, causing the drive shaft 9 to
move in the circumferential direction of the rocking shaft 4. Thus,
the roller shaft 7 is operated in synchronization with this movement
via the arm 10 so as to be moved to the rotating cam 3-side end portion
of the guide portion 5b, whereby the relative distance between the
center axis 02 of the rocking shaft 4 and the roller 8 changes.
[0046]
Further, as shown in FIG. l, while the roller 8 provided to the
rocking cam 5 is in contact with the base surface 3a of the rotating
cam 3, the rocking cam 5 is not rocked to the intake valve 11 side,
the rocker arm 6 is urged to the rocking cam 5 side by the urging
force of the spring 17, and also the intake valve 11 is urged to the
rocker arm 6 side by the urging force of the valve spring 22. Thus,
the lift of the intake valve 11 does not occur and the intake valve
11 is brought into a closed state.
[0047]
In this state, the roller 14 is located at the position corresponding
to the base circle portion 5c of the cam surface 5a of the rocking
cam 5. Since no large abutment force acts between the roller 14 and
the base circle portion 5c in the valve closure state, a sufficient
durability can be secured even through the width Ll of the base circle
portion 5c is small.
[0048]
Then, when the rotating cam 3 is rotated via the camshaft 2 due
to the rotation of the crankshaft of the internal combustion engine,
as shown in FIG. 2, the roller 8 is pressed on by the nose surface
3b. As the roller 8 is further pressed, the rocking cam 5 is pressed
11

CA 02541726 2006-02-27
via the roller shaft 7, causing the rocking cam 5 to rock
counterclockwise in FIG. 1 against the urging force of the spring
15.
[0049]
Through the rocking movement of the rocking cam 5, the portion of
the cam surface 5a of the rocking cam 5 which presses the roller 14
changes from the base circle portion 5c to the lift portion 5d via
the ramp portion 5e, and the rocker arm 6 is turned via the roller
shaft 13 to the intake valve 11 side. In this way, a relative distance
M between the center axis 02 of the rocking shaft 4 and the roller
14 in contact with the cam surface 5a of the rocking cam 5 as shown
in FIG. 1 is largely changed to a relative distance N between the
center axis 02 of the rocking shaft 4 and the roller 14 in contact
with the cam surface 5a of the rocking cam 5 as shown in FIG. 2. The
rocker arm 6 thus undergoes large rocking movement to the intake valve
6 side.
[0050]
Then, the valve pressing portion 6a formed at the distal end portion
of the rocker arm 6 that has thus undergone large rocking movement
to the intake valve 11 side presses on the upper surface of the shim
23 to push down the intake valve 11 by a large distance. As described
above, by moving the roller shaft 7 to the end portion of the guide
portion 5b in the rotating cam 3 side to make the relative distance
between the center axis 02 of the rocking shaft 4 and the roller 8
variable, the relative distance between the center axis 02 of the
rocking shaft 4 and the roller 14 in contact with the cam surface
5a of the rocking cam 5 can be largely changed, whereby the intake
valve 11 can be pushed down by a large distance to bring the intake
valve 11 into an open state at the maximum lift amount.
[0051]
In the case where the intake valve 11 is opened in this way, the
width L2 of the lift portion 5d is made large because a large reaction
force acts on the cam surface 5a of the rocking cam 5, thereby making
it possible to secure strength.
[0052]
Next, detailed description will be made on the operation of the
12

CA 02541726 2006-02-27
variable valve mechanism 1 of the internal combustion engine when
the minimum lift amount is required, with reference to FIG. 3 and
4.
[0053]
Here, FIG. 3 is a longitudinal sectional view of the main portion
of the variable valve mechanism for the internal combustion engine
according to Embodiment 1 of the present invention when the minimum
lift amount is required, illustrating the state in which the intake
valve is closed. FIG. 4 is a longitudinal sectional view of the main
portion of the variable valve mechanism for the internal combustion
engine according to Embodiment 1 of the present invention when the
minimum lift amount is required, illustrating the state in which the
intake valve is open.
[0054]
First, as shown in FIG. 3, in the state as shown in FIG. 1 where
the roller shaft 7 is retained at the rotating cam 3-side end portion,
the roller shaft 7 is moved to the rocking shaft 4-side end portion
of the guide portion 5b, thereby changing the relative distance
between the center axis 02 of the rocking shaft 4 and the roller 8.
[0055]
That is, the rocking shaft 4 ~s turned within a predetermined angle
range by the actuator, causing the drive shaft 9 to move in the
circumferential direction of the rocking shaft 4. Accordingly, the
roller shaft 7 is operated in synchronization with this movement via
the arm 10 so that the roller shaft 7 is moved to the rocking shaft
4-side end portion of the guide portion 5b from the state where it
is retained at the rotating cam 3-side end portion, whereby the
relative distance between the center axis 02 of the rocking shaft
4 and the roller 8 decreases. Then, the rocking cam 5 turns from the
position as shown in FIG. 1 to the position as shown in FIG. 3 due
to the urging force of the spring 15.
[0056]
Further, as shown in FIG. 3, while the roller 8 provided to the
rocking cam 5 is in contact with the base surface 3a of the rotating
cam 3, the rocking cam 5 is not rocked to the intake valve 11 side,
the rocker arm 6 is urged to the rocking cam 5 side by the urging
13

CA 02541726 2006-02-27
force of the spring 17, and also the intake valve 11 is urged to the
rocker arm 6 side by the urging force of the valve spring 22. Thus,
the lift of the intake valve 11 does not occur and the intake valve
11 is brought into a closed state.
[0057]
When the rotating cam 3 is rotated via the camshaft 2 due to the
rotation of the crankshaft of the internal combustion engine, as shown
in FIG. 4, the roller 8 is pressed on by the nose surface 3b, and
the rocking cam 5 is pressed via the roller shaft 7, causing the rocking
cam 5 to rock counterclockwise in FIG. 3 against the urging force
of the spring 15.
[0058]
As the rocking cam 5 is further rocked, the roller 14 in contact
with the rocking shaft 4-side distal end portion of the cam surface
5a of the rocking cam 5 is pushed down to the intake valve 11 side
by using the range of the cam surface 5a from the rocking shaft 4-side
distal end portion to the center portion thereof, whereby the rocker
arm 6 is rocked to the intake valve 11 side via the roller shaft 13.
In this way, a relative distance P between the center axis 02 of the
rocking shaft 4 and the roller 14 in contact with the cam surface
5a of the rocking cam 5 as shown in FIG. 3 undergoes a small change
to become a relative distance Q between the center axis 02 of the
rocking shaft 4 and the roller 14 in contact with the cam surface
5a of the rocking cam 5 as shown in FIG. 4. The rocker arm 6 thus
undergoes small rocking movement to the intake valve side.
[0059]
Then, the valve pressing portion 6a formed at the distal end portion
of the rocker arm 6 that has thus undergone small rocking movement
to the intake valve 11 side presses on the upper surface of the shim
23 to push down the intake valve 11 by a small distance. In this way,
by moving the roller shaft 7 to the rocking shaft 4-side end portion
of the guide portion 5b to make the relative distance between the
center axis 02 of the rocking shaft 4 and the roller 8 variable, the
relative distance between the center axis 02 of the rocking shaft
4 and the roller 14 in contact with the cam surface 5a of the rocking
cam 5 can be subj ected to a small change to push down the intake valve
14

CA 02541726 2006-02-27
11 by a small distance, whereby, in Embodiment l, the intake valve
11 can be brought into an open state at the minimum lift amount.
[0060]
Further, although the width Ll of the base circle portion 5c is
small, since no large load acts on this portion, a requisite strength
can be secured for the base circle portion 5c. Because a large load
acts on the lift portion 5d, the width L2 thereof is made larger to
secure a requisite strength.
[0061]
Weight of the rocking cam 5 can be reduced because of the small width
Ll of the base circle portion 5c. This results in a reduction in
inertia force of the rocking cam 5 at the time of rocking movement,
as well as in a reduction in weight of parts associated with the rocking
cam 5 (e . g . spring 15 ) . This allows the whole system to be smaller
while reducing wear on a contact portion of the cam surface 5a.
[0062]
Particularly, the base circle portion 5c is formed in a position
apart from the center axis 02, and therefore can more contribute to
the reduced inertia force.
[0063]
In the variable valve mechanism 1 of the internal combustion engine
constructed as described above, the rocking cam 5 is provided with
the roller 8 or the rotating cam abutment portion that comes into
contact with the rotating cam 3 to transmit the drive force from the
rotating cam to the rocking cam 5. The valve mechanism 1 is provided
with the variable abutment portion mechanism for making the relative
distance between the roller 8 and the center axis 02 of the rocking
shaft 4 variable by making the roller 8 movable; the lift amount or
the like of each valve is made variable by thus making the relative
distance variable, whereby the structure can be simplified to achieve
low-cost construction.
[0064]
Further, the load from the rotating cam 3 is input to the roller
8, and the load is directly transmitted from the roller 8 tc the guide
portion 5a of the rocking cam 5. Then, the load is transmitted from
the rocking cam 5 to the intake valve 11 via the rocker arm 6. Thus,
IJ

CA 02541726 2006-02-27
no large load acts on the arm 10 that supports the roller 8, and since
the arm 10 serves the sole function of moving the roller 8 along the
guide portion 5a, not so large strength is required for the arm 10.
[Embodiment 2 of the Invention]
[0065]
FIGS. 6 through 8 illustrate Embodiment 2 of the present invention.
FIG. 6 is a longitudinal sectional view of the main portion of the
variable valve mechanism for the internal combustion engine when the
maximum lift amount is required, illustrating the state in which the
intake valve is closed. FIG. 7 is a longitudinal sectional view of
the main portion of the variable valve mechanism for the internal
combustion engine when the minimum lift amount is required,
illustrating the state in which the intake valve is closed.
[0066]
In Embodiment 2, the rocker arm 6 which opens and closes an intake
valve 11 as in Embodiment 1 is not provided, but a rocking cam 5
directly moves the intake valve 11 upward and downward to open and
close the intake valve 11.
[0067]
As shown in FIGs. 6 through 8, the rocking cam 5 is formed in the
shape of a comma-shaped bead. The rocking cam 5 is fitted on the
peripheral surface of a rocking shaft 4 and supported so as to be
rockable about the center axis 02 of the rocking shaft 4.
[0068]
More specifically, as shown in FIG. 8, the rocking cam 5 includes
a cam surface 5a having a base circle portion 5c, a lift portion 5d
and a ramp portion 5e. A width L1 of a contact surface of the base
circle portion 5c is formed smaller than a width L2 of a contact surface
of the lift portion 5d. Further, the bottom end of the rocking cam
is formed with a cam surface 5a. The cam surface 5a is curved toward
the intake valve 11 to form a projection, and depresses a lifter 26
of the intake valve 11 to vertically move the intake valve 11. The
upper portion of the cam surface 5a is formed with a guide portion
5b, along which a roller shaft 7 having a roller 8 slides.
[0069]
The roller shaft 7 is connected to one end portion 10a of an arm
16

CA 02541726 2006-02-27
connected to a drive shaft 9. A roller 8 rotatably supported with
the roller shaft 7 comes into contact with a rotating cam 3.
[0070]
The rocking shaft 4 is provided with a spring (not shown) for urging
the rocking cam 5 toward the rotating cam 3. The rocking cam 5 is
thereby urged toward the rotating cam 3 by the urging force of the
spring, so that the peripheral surface of the roller shaft 7 is
normally in contact with the guide portion 5b, and the peripheral
surface of the roller 8 is normally in contact with a base surface
3a or a nose surface 3b of the rotating cam 3.
[0071]
There is provided, below the cam surface 5a of the rocking cam 5,
the lifter 26 attached on the intake valve 11. Thus, the swinging
motion of the rocking cam 5 directly moves the intake valve 11 upward
and downward.
[0072]
Thus, when the rocking shaft 4 is rotated by a predetermined angle
by the actuator, the drive shaft 9 provided to the rocking shaft 4
is turned by a predetermined angle about the center axis 02 of the
rocking shaft 4, and the roller shaft 7 is operated in synchronization
with this turning movement through the arm 10. The roller shaft 7
can be thus moved within the guide portion 5b while keeping the
distance between the center axis 03 of the roller shaft 7 and the
center axis 04 of the drive shaft 9 constant with the arm 10, whereby
the relative distance between the center axis 02 of the rocking shaft
4 and the roller 8 can be made variable. Therefore, the lift amount
and the maximum lift timing of the intake valve 11 can be adjusted
and made variable.
[0073]
As shown in FIG. 6, when the roller shaft 7 is displaced to the
distal end portion of the guide portion 5b so that the relative
distance between the center axis 02 of the rocking shaft 4 and the
roller 8 is made variable, the intake valve 11 is depressed with the
cam surface 5a of the rocking cam 5 by a larger amount. A maximum
lift amount is thus obtained in Embodiment 2.
[0074]
17

CA 02541726 2006-02-27
As shown in FIG. 7, when the roller shaft 7 is displaced to the
rocking shaft 4 side of the guide portion 5b so that the relative
distance between the center axis 02 of the rocking shaft 4 and the
roller 8 is made variable, the intake valve 11 is depressed with the
cam surface 5a of the rocking cam 5 by a smaller amount . A minimum
lift amount is thus obtained in Embodiment 2.
[0075]
Further, although the width L1 of the base circle portion 5c is
small, as in the Embodiment described above, since no large load acts
on this portion, a requisite strength can be secured for the base
circle portion 5c. Because a large load acts on the lift portion
5d, the width L2 thereof is made larger to secure a requisite strength.
[0076]
Weight of the rocking cam 5 can be reduced because of the small width
Ll of the base circle portion 5c. This results in a reduction in
inertia force of the rocking cam 5 at the time of rocking movement,
as well as in a reduction in weight of parts associated with the rocking
cam 5 (e.g. spring 15) . This allows the whole system to be smaller
while reducing wear on a contact portion of the cam surface 5a.
[0077]
Otherwise, Embodiment 2 is of the same construction and operation
as Embodiment 1 of the present invention, so repetitive description
will not be repeated.
[Embodiment 3 of the Invention]
[0078]
FIGS. 9 through 11 are longitudinal sectional views of the main
portion of valve mechanism for an internal combustion engine
according to Embodiment 3 of the present invention, illustrating a
state in which the intake valve is closed.
[0079]
In Embodiment 3, a rocker arm 6 has a roller 14 that comes into
contact with a cam surface 5a of a rocking cam 5, a roller arm 6c
for supporting the roller 14, which is operated in synchronization
with the rocking motion of the rocking cam 5, and a rocker arm main
body 6d that rocks in synchronization with the roller arm 6c to
vertically move an intake valve 11.
18

CA 02541726 2006-02-27
[0080]
A leaf spring 28 is used to urge the roller arm 6c to the rocking
cam 5 side to bring the roller 14 and the cam surface 5a of the rocking
cam 5 into contact with each other.
[0081]
As shown in FIG. 10, as in the Embodiments described above, the cam
surface 5a has a base circle portion 5c, a lift portion 5d, and a
ramp portion 5e, and a width Ll of the base circle portion 5c is formed
smaller than a width L2 of the lift portion 5d.
[0082]
Further, the roller arm 6c is freely movable to a predetermined
position. By changing the contact position between the roller 14
provided to the roller arm 6c and the cam surface 5a of the rocking
cam 5, the life amount of each valve or the like can be adjusted.
[0083]
Specifically, as shown in FIG. 9, an eccentric shaft 29 is fixedly
provided to the rocker arm shaft 12 in such a manner that a center
axis 07 thereof is located in parallel and eccentrically to the center
axis 05 of the rocker arm shaft 12. The roller arm 6c of the rocker
arm 6 is rotatably locked onto the eccentric shaft 29 by means of
the leaf spring 28.
[0084]
The roller arm 6c has an engaging portion 6e formed at its one end.
The engaging portion 6e engages with the outer peripheral surface
of the eccentric shaft 29, and is so shaped as to be capable of sliding
on the outer peripheral surface of the eccentric shaft 29. Formed
at a position adjacent to the engaging portion 6e is a fitting
engagement portion 6f with which the leaf spring 28 for integrally
locking the roller arm 6c and the eccentric shaft 29 in place is brought
into fitting engagement so as to prevent dislodging thereof.
Further, a through-hole 6g, with which the roller shaft 13 supporting
the roller 14 that slides on the cam surface 5a of the rocking cam
is brought into fitting engagement, is formed at the other end of
the roller arm 6c. Formed below the through-hole 6g is a pressing
portion 6h for pressing the rocker arm main body 6d to the intake
valve 11 side when the roller arm 6c rocks to the intake valve 11
19

CA 02541726 2006-02-27
side in synchronization with the rocking motion of the rocking cam
5.
[0085]
Further, the rocker arm main body 6d of the rocker arm 6 is rockably
supported and arranged on the rocker arm shaft 12, and has the valve
pressing portion 6a formed at is distal end portion. The valve
pressing portion 6a presses on the upper surface of the shim 23 fitted
on the intake valve 11. Further, a contact surface 6i with which
a distal end portion 28b of the leaf spring 28, which will be described
later, comes into contact is formed above the valve pressing portion
6a, and a guide portion 6j pressed on by the pressing portion 6h formed
in the rocker arm 6c is formed above the contact surface 6i.
[0086]
Further, the leaf spring 28 is formed into a predetermined
configuration by bending a planar spring at several locations. More
specifically, the leaf spring 28 is formed in a configuration allowing
fitting engagement with the fitting engagement portion 6f of the
roller arm 6c and with the eccentric shaft 29, and has formed therein
a locking portion 28a for integrally locking the roller arm 6c and
the eccentric shaft 29 onto each other. Further, the distal end
portion 28b of the leaf spring 28 on the roller arm 6c side extends
to the roller 14 side and comes into contact with the contact surface
6i formed in the rocker arm main body 6d.
[0087]
Further, the leaf spring 28 is formed in such a configuration as
to urge the roller arm 6c and the rocker arm main body 6d so as to
spread out from each other when the roller arm 6c and the eccentric
shaft 29 are integrally locked onto each other by the locking portion
28a.
[0088]
Further, a predetermined clearance A is provided between a pressing
portion 6h of the roller arm 6c and a guide portion 6j of the rocker
arm main body 6d.
[0089]
Thus, since the roller arm 6c is integrally locked onto the eccentric
shaft 29 by the leaf spring 28 so that the roller arm 6c can slide

CA 02541726 2006-02-27
on the outer peripheral surface of the eccentric shaft 29, when the
rocking cam 5 is rocked, the roller arm 6c is caused via the roller
14 and the roller shaft 13 to rock to the intake valve 11 side against
the urging force of the leaf spring 28. Further, as the rocker arm
6c is rocked to the intake valve 11 side, the pressing portion 6h
of the roller arm 6c presses on the guide portion 6j of the rocker
arm main body 6d, causing the rocker arm main body 6d to rock to the
intake valve 11 side, thereby making it possible to open and close
the intake valve 11.
[0090]
Further, the roller arm 6c is urged to the rocking cam 5 side by
the leaf spring 28, so the outer peripheral surface of the roller
14 provided to the roller arm 6c is held in constant contact with
the cam surface 5a of the rocking cam 5.
[0091]
Further, an actuator (not shown) for rotating the rocker arm shaft
12 within a predetermined angle range about the center axis 05 is
connected to one end portion of the rocker arm shaft 12. Connected
to the actuator is control means (not shown) for controlling the angle
of the actuator according to the operational state of the internal
combustion engine.
[0092]
Thus, when the rocker arm shaft 12 is rotated by a predetermined
angle by the actuator, the eccentric shaft 29 provided to the rocker
arm shaft 12 is turned by a predetermined angle about the center axis
05 of the rocker arm shaft 12. Further, when the eccentric shaft
29 is turned by the predetermined angle, the roller arm 6c operating
in synchronization therewith is moved, for example, from the position
indicated by the solid line in FIG. 9 to a predetermined position
indicated by the chain double-dashed line in FIG. 9. Then, once the
roller arm 6c has been moved to the predetermined position, the
contact point where the cam surface 5a of the rocking cam 5 and the
roller 14 provided to the roller arm 6c come into contact with each
other changes. The rocking amount of the rocker arm main body 6d
can be thus changed, which makes it possible to adjust the lift amount
or the like of the intake valve 11 that is vertically moved by the
21

CA 02541726 2006-02-27
rocker arm 6.
[0093]
Further, even in the case where a predetermined clearance is not
provided between the valve pressing portion 6a of the rocker arm main
body 6d and the intake valve 11, the predetermined clearance (A)
provided between the pressing portion 6h and the guide portion 6j
allows the intake valve 11 to be reliably opened/closed even when,
due to a rise in the temperature of the internal combustion engine,
the intake valve 11 undergoes thermal expansion to cause upward
jumping of the valve.
[0094]
Also with the valve mechanism 1 for an internal combustion engine
constructed as described above, in which the lift amount or the like
of each valve can be adjusted by making the roller arm 6c be movable
to the predetermined position and changing the contact position
between the roller 14 provided to the roller arm 6c and the cam surface
5a of the rocking cam 5, the roller arm 6c is urged toward the rocking
cam 5 side by the leaf spring 28. Accordingly, when the roller arm
6c has been moved to the predetermined position and the contact
position between the roller 14 and the cam surface 5a changes, the
roller 14 of the rocker arm 6 and the cam surface 5a of the rocking
cam 5 constantly come into contact with each other, thereby making
it possible to prevent adhesive wear.
[0095]
Further, although the width Ll of the base circle portion 5c is
small, as in the Embodiments described above, since no large load
acts on this portion, a requisite strength can be secured for the
base circle portion 5c. Because a large load acts on the lift portion
5d, the width L2 thereof is made larger to secure a requisite strength.
[0096]
Weight of the rocking cam 5 can be reduced because of the small width
Ll of the base circle portion 5c. This results in a reduction in
inertia force of the rocking cam 5 at the time of rocking movement,
as well as in a reduction in weight of parts associated with the rocking
cam 5 (e. g. spring 15).
[0097]
22

CA 02541726 2006-02-27
Particularly, the base circle portion 5c is formed in a position
apart from the center axis 02, and therefore can more contribute to
the reduced inertia force.
[0098]
Otherwise, Embodiment 3 is of the same construction and operation
as Embodiment 1 of the present invention, so repetitive description
will not be repeated.
[0099]
Otherwise, Embodiment 3 is of the same construction and operation
as Embodiment 1 of the present invention, so repetitive description
will not be repeated.
[Embodiment 4 of the Invention]
[0100)
FIGS . 12 and 13 are longitudinal sectional views of the main portion
of a valve mechanism for an internal combustion engine according to
Embodiment 4 of the present invention, illustrating a state in which
the intake valve is closed.
[0101]
The valve mechanism 1 for an internal combustion engine according
to Embodiment 4 is capable of adjusting the lift amount or the like
of each valve by making the rocking shaft 4 movable to a predetermined
position.
[0102]
Specifically, as shown in FIG. 12, a roller 33 is arranged on the
outer peripheral surface of the rocking shaft 4. The roller 33 is
in contact with a guide portion 19a formed in the cylinder head main
body 19 for guiding the rocking shaft 4 to a predetermined position.
Further, the rocking shaft 4 is provided to the cylinder head main
body 19 such that, when the rocking cam 5 is pressed by a control
cam 34 that will be described next, the rocking shaft 4 can move in
synchronization with the rocking cam 12 within a range from a position
indicated by the solid line in FIG. 12 to that indicated by the chain
double-dashed line in FIG. 12.
[0103]
The control cam 34 is fixed onto the outer peripheral surface of
a control shaft 35 provided in parallel to the camshaft 2. Further,
23

CA 02541726 2006-02-27
the outer peripheral portion of the control cam 34 contacts the
rocking cam 5 and is formed in a configuration allowing the rocking
shaft 4 to be guided to a predetermined position by rotating the
control cam 34 in a predetermined angle.
[0104]
As shown in FIG. 13, the cam surface 5a of the rocking cam 5 has
a base circle portion 5c, a lift portion 5d, and a ramp portion 5e,
and a width L1 of the base circle portion 5c is formed smaller than
a width L2 of the lift portion 5d.
[0105]
Further, an actuator (not shown) for rotating the control shaft
35 within a predetermined angle range about a center axis 08 of the
control shaft 35 is connected to one end portion of the control shaft
35. Connected to the actuator is control means (not shown) for
controlling the angle of the actuator according to the operational
state of the internal combustion engine.
[0106]
Further, the rocker arm 6, which makes reciprocating motion while
rocking within a predetermined range in synchronization with the
rocking cam 5, is of the same construction as that of Embodiment 1.
That is, the rocker arm 6 has the valve pressing portion 6a formed
therein, is provided with the roller shaft 13 and the roller 14, and
is rockably supported on the rocker arm shaft 12.
[0107]
Further, as in Embodiment 1, the rocker arm shaft 12 is provided
with the torsion spring 17 as a spring member for bringing the roller
14 and the cam surface 5a into constant contact with each other.
[0108]
Thus, when the control shaft 35 is turned by a predetermined angle
by the actuator, the control cam 34 is rotated by a predetermined
angle about the center axis 08 of the control shaft 35. When the
control cam 34 is rotated by the predetermined angle, by the control
cam 34, the roller 33 is caused via the rocking cam 5 to slide on
the guide portion 19a of the cylinder head main body 19 so as to be
moved, for example, from the position indicated by the solid line
in FIG. 12 to a predetermined position indicated by the chain
24

CA 02541726 2006-02-27
double-dashed line in FIG. 12. Then, as the rocking shaft 4 is moved,
the position of the cam surface 5a of the rocking cam 5 changes. The
rocking amount of the rocker arm 6 can be thus changed, which makes
it possible to adjust the lift amount or the like of the intake valve
11 that is vertically moved by the rocker arm 6.
[0109]
Also with the valve mechanism 1 constructed as described above,
which makes the lift amount or the like of each valve variable by
moving the rocking shaft 4 to a predetermined position, the rocker
arm 6 is urged to the rocking cam 5 side by the torsion spring 17,
so even when the rocking shaft 4 has been moved to the predetermined
position, and the position of the cam surface 5a of the rocking cam
changes, the roller 14 of the rocker arm 6 and the cam surface 5a
of the rocking cam 5 constantly come into contact with each other.
Adhesive wear can be thus prevented.
[0110]
Further, although the width L1 of the base circle portion 5c is
small, as in the Embodiments described above, since no large load
acts on this portion, a requisite strength can be secured for the
base circle portion 5c. Because a large load acts on the lift portion
',d, the width L2 thereof is made larger to secure a requisite strength.
[0111]
Weight of the rocking cam 5 can be reduced because of the small width
Ll of the base circle portion 5c. This results in a reduction in
inertia force of the rocking cam 5 at the time of rocking movement,
as well as in a reduction in weight of parts associated with the rocking
cam 5 (e. g. spring 15).
[0112]
Particularly, the base circle portion 5c, formed in a position apart
from the center axis 02, can more contribute to the reduced inertia
force.
[0113]
Otherwise, Embodiment 4 is of the same construction and operation
as Embodiment 1 of the present invention, so repetitive description
will not be repeated.
[Embodiment 5 of the Invention]

CA 02541726 2006-02-27
[0114]
FIGS . 14 and 15 are longitudinal sectional views of the main portion
of a valve mechanism for an internal combustion engine according to
Embodiment 5 of the present invention, illustrating a state in which
the intake valve is closed.
[0115]
Embodiment 5 provides the valve mechanism 1 for an internal
combustion engine in which the rotating cam 3 has a tapered
configuration, and the contact position between the outer peripheral
portion of the rotating cam 3 and the rocking cam 5 is changed by
moving the rotating cam 3 in the direction of the center axis Ol of
the camshaft 2, thereby making it possible to adjust the lift amount
or the like of each valve.
[0116]
Specifically, as shown in FIG. 14, the rotating cam 3 is fixed onto
the outer peripheral surface of the camshaft 2. The outer peripheral
portion of the rotating cam 3 is constructed with the base surface
3a that is arc-shaped in plan view, and the nose surface 3b projecting
from the base surface 3a. The base surface 3a and the nose surface
3b are formed in the tapered configuration in the direction of the
center axis Ol (in the direction perpendicular to the sheet plane)
of FIG. 14.
[0117]
Further, an actuator (not shown) for moving the camshaft 2 within
a predetermined range in the direction of the center axis O1 is
connected to one end portion of the camshaft 2. Connected to the
actuator is control means (not shown) for controlling the angle of
the actuator according to the operational state of the internal
combustion engine.
[0118]
Further, the outer peripheral surface of the roller 8 provided to
the rocking cam 5 rocked by the rotating cam 3 is capable of sliding
on the base surface 3a and base surface 3b of the rotating cam 3 formed
in the tapered configuration.
[0119]
Further, as shown in FIG. 15, the cam surface 5a of the rocking cam
26

CA 02541726 2006-02-27
has a base circle portion 5c, a lift portion 5d, and a ramp portion
5e, and a width Ll of the base circle portion 5c is formed smaller
than a width L2 of the lift portion 5d.
[0120]
Further, the rocker arm 6, which makes reciprocating motion while
rocking within a predetermined range in synchronization with the
rocking cam 5, is of the same construction as that of Embodiment 4.
That is, the rocker arm 6 has the valve pressing portion 6a formed
therein, is provided with the roller shaft 13 and the roller 14, and
is rockably supported on the rocker arm shaft 12.
[0121]
Further, as in Embodiment 4, the rocker arm shaft 12 is provided
with the torsion spring 17 for bringing the roller 14 and the cam
surface 5a into constant contact with each other.
[0122]
Thus, when the camshaft 2 moves within a predetermined range in
the direction of the center axis O1 by the actuator, the rotating
cam 3 moves within a predetermine range in the direction of the center
axis Ol of the camshaft 2. Since the rotating cam 3 is formed in
the tapered configuration, when the rotating cam 3 is moved with the
predetermined range, the rocking cam 5 is caused via the roller shaft
7 and the roller 8 to move, for example, from the position indicated
by the solid line in FIG. 14 to a predetermined position indicated
by the double-dashed chain line in FIG. 14. Then, when the rocking
cam 5 has been moved to the predetermined position, the position of
the cam surface 5a of the rocking cam 5 changes. Therefore, the
rocking amount of the rocker arm 6 can be changed, which makes it
possible to adjust the lift amount or the like of the intake valve
11 that is vertically moved by the rocker arm 6.
[0123]
Also with the valve mechanism 1 constructed as described above,
in which the rotating cam 3 is tapered, and the lift amount or the
like of each valve variable is made variable by moving the rotating
cam 3 in the direction of the center axis Ol of the camshaft 2 and
changing the contact position between the outer peripheral portion
of the rotating cam 3 and the rocking cam 5, the rocker arm 6 is urged
27

CA 02541726 2006-02-27
to the rocking cam 5 side by the torsion spring 17, so even when the
rocking shaft 4 has been moved to the predetermined position, and
the position of the cam surface 5a of the rocking cam 5 changes, the
roller 14 of the rocker arm 6 and the cam surface 5a of the rocking
cam 5 constantly come into contact with each other. Adhesive wear
can be thus prevented.
[0124]
Further, although the width Ll of the base circle portion 5c is
small, as in the Embodiments described above, since no large load
acts on this portion, a requisite strength can be secured for the
base circle portion 5c. Because a large load acts on the lift portion
5d, the width L2 thereof is made larger to secure a requisite strength.
[0125]
Weight of the rocking cam 5 can be reduced because of the small width
Ll of the base circle portion 5c. This results in a reduction in
inertia force of the rocking cam 5 at the time of rocking movement,
as well as in a reduction in weight of parts associated with the rocking
cam 5 (e. g. spring 15).
[0126]
Particularly, the base circle portion 5c is formed in a position
apart from the center axis 02, and therefore can more contribute to
the reduced inertia force.
[0127]
Otherwise, Embodiment 5 is of the same construction and operation
as Embodiment 1 of the present invention, so repetitive description
will not be repeated.
[0128]
It should be noted that while, in the Embodiments described above,
the present invention is applied to the variable valve mechanism 1
provided with the rocking cam 5, the present invention is not limited
to this construction. The present invention may also be applied to
any valve mechanism incapable of changing the lift amount or the like.
[0129]
Description of Reference Numerals and Symbols
l: variable valve mechanism
2: camshaft
28

CA 02541726 2006-02-27
3: rotating cam
4: rocking shaft
5: rocking cam
5a: cam surface
5b: guide portion
5c: base circle portion
5d: lift portion
5e: ramp portion
6: rocker arm
7: roller shaft
8: roller (rotating cam abutting portion)
9: drive shaft
10: arm (variable abutment portion mechanism)
L1: width of base circle portion
L2: width of lift portion
29

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

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Event History

Description Date
Application Not Reinstated by Deadline 2010-08-25
Time Limit for Reversal Expired 2010-08-25
Deemed Abandoned - Failure to Respond to Maintenance Fee Notice 2009-08-25
Letter Sent 2009-02-17
Amendment Received - Voluntary Amendment 2009-01-08
Request for Examination Requirements Determined Compliant 2009-01-08
All Requirements for Examination Determined Compliant 2009-01-08
Request for Examination Received 2009-01-08
Letter Sent 2007-03-22
Inactive: Single transfer 2007-01-30
Inactive: Cover page published 2006-06-21
Inactive: Courtesy letter - Evidence 2006-06-20
Inactive: Notice - National entry - No RFE 2006-06-16
Inactive: Inventor deleted 2006-06-16
Application Received - PCT 2006-05-05
Application Published (Open to Public Inspection) 2006-03-02
National Entry Requirements Determined Compliant 2006-02-27

Abandonment History

Abandonment Date Reason Reinstatement Date
2009-08-25

Maintenance Fee

The last payment was received on 2008-07-18

Note : If the full payment has not been received on or before the date indicated, a further fee may be required which may be one of the following

  • the reinstatement fee;
  • the late payment fee; or
  • additional fee to reverse deemed expiry.

Patent fees are adjusted on the 1st of January every year. The amounts above are the current amounts if received by December 31 of the current year.
Please refer to the CIPO Patent Fees web page to see all current fee amounts.

Fee History

Fee Type Anniversary Year Due Date Paid Date
Basic national fee - standard 2006-02-27
MF (application, 2nd anniv.) - standard 02 2006-08-25 2006-08-21
Registration of a document 2007-01-30
MF (application, 3rd anniv.) - standard 03 2007-08-27 2007-07-24
MF (application, 4th anniv.) - standard 04 2008-08-25 2008-07-18
Request for examination - standard 2009-01-08
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
YAMAHA HATSUDOKI KABUSHIKI KAISHA
Past Owners on Record
HIDEO FUJITA
KOICHI HATAMURA
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

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({010=All Documents, 020=As Filed, 030=As Open to Public Inspection, 040=At Issuance, 050=Examination, 060=Incoming Correspondence, 070=Miscellaneous, 080=Outgoing Correspondence, 090=Payment})


Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Drawings 2006-02-26 15 337
Claims 2006-02-26 1 42
Description 2006-02-26 29 1,214
Representative drawing 2006-03-22 1 24
Abstract 2006-02-26 1 7
Reminder of maintenance fee due 2006-06-18 1 110
Notice of National Entry 2006-06-15 1 192
Request for evidence or missing transfer 2007-02-27 1 101
Courtesy - Certificate of registration (related document(s)) 2007-03-21 1 105
Acknowledgement of Request for Examination 2009-02-16 1 176
Courtesy - Abandonment Letter (Maintenance Fee) 2009-10-19 1 172
PCT 2006-02-26 3 113
Correspondence 2006-06-15 1 28
Fees 2006-08-20 1 41
Fees 2007-07-23 2 126
Fees 2008-07-17 1 37