U.S. patent application number 13/859369 was filed with the patent office on 2013-12-26 for variably operated valve system for internal combustion engine.
This patent application is currently assigned to HITACHI AUTOMOTIVE SYSTEMS, LTD.. The applicant listed for this patent is HITACHI AUTOMOTIVE SYSTEMS, LTD.. Invention is credited to Makoto NAKAMURA.
Application Number | 20130340694 13/859369 |
Document ID | / |
Family ID | 49713815 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130340694 |
Kind Code |
A1 |
NAKAMURA; Makoto |
December 26, 2013 |
VARIABLY OPERATED VALVE SYSTEM FOR INTERNAL COMBUSTION ENGINE
Abstract
A variably operated valve system for an internal combustion
engine, a valve stop mechanism (11) makes at least one of a pair of
fulcrum members lost motion to stop open-and-closure drives for one
of two engine valves per cylinder and a stop of open-and-closure
drives for the one of the engine valves is inhibited, in a case
where a lost motion quantity of the valve stop mechanism exceeds a
predetermined value (M3).
Inventors: |
NAKAMURA; Makoto;
(Zushi-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HITACHI AUTOMOTIVE SYSTEMS, LTD. |
Hitachinaka-shi |
|
JP |
|
|
Assignee: |
HITACHI AUTOMOTIVE SYSTEMS,
LTD.
Hitachinaka-shi
JP
|
Family ID: |
49713815 |
Appl. No.: |
13/859369 |
Filed: |
April 9, 2013 |
Current U.S.
Class: |
123/90.12 |
Current CPC
Class: |
F01L 2305/00 20200501;
F01L 1/267 20130101; F01L 13/0026 20130101; F01L 1/2405 20130101;
F01L 13/0005 20130101; F01L 1/10 20130101; F01L 2013/0073
20130101 |
Class at
Publication: |
123/90.12 |
International
Class: |
F01L 1/26 20060101
F01L001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2012 |
JP |
2012-140574 |
Claims
1. A variably operated valve system comprising: a drive shaft to
which a rotation driving force is transmitted from an engine
crankshaft and on an outer periphery of which drive cams are
disposed; two swing cams that operate two engine valves per engine
cylinder to open against spring forces of respective valve springs;
a transmission mechanism that converts rotation motions of the
drive cams into swing motions and transmits the converted swing
motions to the respective swing cams; a pair of swing arms
interposed between the respective swing cams and the respective
engine valves to operate the respective engine valves to open or
close; a pair of fulcrum members each of which provides a swing
fulcrum of each of the swing arms; a control mechanism that varies
a posture of the transmission mechanism to variably control a lift
quantity of each of the engine valves; a valve stop mechanism that
makes at least one of the pair of fulcrum members lost motion to
stop open-and-closure drives for one of the two engine valves; and
valve stop inhibit means for inhibiting a stop of open-and-closure
drives for the one of the engine valves, in a case where a lost
motion quantity of the valve stop mechanism exceeds a predetermined
value.
2. A variably operated valve system for an internal combustion
engine, comprising: drive cams to which a rotational force is
transmitted from a crankshaft; engine valves, two of the engine
valves being mounted in each of engine cylinders and each engine
valve being biased toward a valve closure direction by means of a
spring force of a corresponding one of valve springs; swing cams
that make the respective engine valves open operation against
spring forces of valve springs; a transmission mechanism that
converts rotation motions of the drive cams into swing motions and
transmits the converted swing motions to the swing cams; a control
mechanism that varies a posture of the transmission mechanism to
variably control a lift quantity of each of the engine valves; a
pair of operational members that swing in accordance with the swing
motions of the swing cams to operate the respective engine valves
to open or close; a valve stop mechanism that absorbs a swing
quantity of one of the pair of operational members to stop
open-and-closure operations of one of the two engine valves; and
valve stop inhibiting means for inhibiting an absorption of a swing
motion of the valve stop mechanism in a case where the swing
quantity of each of the pair of the operational members exceeds a
predetermined quantity.
3. A variably operated valve system for an internal combustion
engine, comprising: a drive cam rotationally driven through a
crankshaft; a pair of engine valves, each engine valve being biased
toward a closure direction by means of a spring force of a valve
spring; a pair of swing cams that swing to drive the pair of engine
valves via a pair of operational members; a transmission mechanism
that converts a rotation motion of the drive cam into a swing
motion and transmits the converted swing motion to the pair of
swing cams; a control mechanism that varies a posture of the
transmission mechanism to vary operation characteristics of the
pair of the engine valves; and a valve stop mechanism disposed on
at least one of the pair of operational members to make a lost
motion to stop a drive of one of the pair of engine valves,
wherein, in a case where a valve lift quantity of one of the pair
of engine valves exceeds a predetermined value, an operation of a
valve stop through the valve stop mechanism is inhibited.
4. The variably operated valve system for the internal combustion
engine as claimed in claim 1, wherein the valve stop mechanism
includes: a retaining hole that holds one of the pair of fulcrum
members movable; and a basing member that biases the one of the
pair of fulcrum members toward a direction of a corresponding one
of the pair of swing arms and the lost motion is made by moving the
one of the pair of fulcrum members against the biasing member.
5. The variably operated valve system for the internal combustion
engine as claimed in claim 4, wherein the pair of fulcrum members
are hydraulic pressure rush adjusters.
6. The variably operated valve system for the internal combustion
engine as claimed in claim 1, wherein the valve stop mechanism is
disposed only in one of the pair of fulcrum members and, when the
lost motion quantity is equal to or below the predetermined value,
only one of the two engine valves corresponding to the one of the
pair of fulcrum members is allowed to be stopped through the valve
stop mechanism.
7. The variably operated valve system for the internal combustion
engine as claimed in claim 1, wherein the valve stop mechanism is
disposed in both of the pair of fulcrum members and, when the lost
motion quantity is equal to or below the predetermined quantity,
both of the two engine valves are allowed to be stopped through the
valve stop mechanism.
8. The variably operated valve system for the internal combustion
engine as claimed in claim 6, wherein the pair of swing cams are
integrally formed.
9. The variably operated valve system for the internal combustion
engine as claimed in claim 4, wherein the swing fulcrum of each of
the pair of each of the pair of swing arms is formed by a spherical
recess section disposed on a corresponding one of the pair of swing
arms and a spherical convex section engaged with the recess
section.
10. The variably operated valve system for the internal combustion
engine as claimed in claim 4, wherein, when the valve stop
inhibiting means mechanically inhibits the lost motion of the one
of the pair of fulcrum members when the lost motion quantity
exceeds the predetermined value.
11. The variably operated valve system for the internal combustion
engine as claimed in claim 4, wherein the control shaft includes a
control cam that is in an eccentricity state to an axial center of
the control shaft, the control cam is inserted through the
transmission mechanism, and the posture of the transmission
mechanism is varied according to a rotation of the control cam.
12. The variably operated valve system for the internal combustion
engine as claimed in claim 10, wherein a limitation of the lost
motion is made by a limitation of a movement of the one of the pair
of fulcrum members by means of a projection section in a movable
range of the one of the pair of fulcrum members.
13. The variably operated valve system for the internal combustion
engine as claimed in claim 10, wherein the valve stop inhibit means
is constituted by a movement purpose hole and a limitation purpose
hole, both of the movement purpose and limitation purpose holes
being disposed in the one of the pair of fulcrum members and in an
inner wall of the retaining hole, and a limitation pin movably
disposed across the movement purpose hole and the limitation
purpose hole and a state in which the one of the pair of fulcrum
members is in a locked state by disposing the limitation pin across
the movement purpose hole and the limitation purpose hole and
another state in which the limitation pin is housed in the movement
purpose hole to enable the one of the pair of fulcrum members to
make the lost motion are controlled.
14. The variably operated valve system for the internal combustion
engine as claimed in claim 13, wherein the valve stop inhibiting
means includes another biasing member disposed in the movement
purpose hole of the one of the pair of fulcrum members to bias the
limitation pin toward a direction of the limitation purpose hole
and a hydraulic pressure circuit that supplies a hydraulic pressure
to press under pressure the limitation pin in another direction of
the movement purpose hole of the one of the pair of fulcrum members
against the biasing force of the other biasing member.
15. The variably operated valve system for the internal combustion
engine as claimed in claim 14, wherein the hydraulic pressure
circuit includes: oil passage holes disposed at a bearing section
of the control shaft and a communication hole penetrated through a
diameter direction of the control shaft to appropriately
communicate with the oil passage holes and wherein, when the
control shaft is rotated through an angle equal to or below a
predetermined rotation angle, both of the oil passage holes and the
communication hole are communicated with each other and, when the
control shaft exceeds the predetermined rotation angle, the
communication between the oil passage holes and communication hole
is interrupted.
16. The variably operated valve system for the internal combustion
engine as claimed in claim 14, wherein, when the lost motion
quantity is smaller than the predetermined value of the lost motion
quantity of the one of the pair of fulcrum members, a hydraulic
pressure is supplied to move the limitation pin toward the
direction of the movement purpose hole against a biasing force of
the other biasing member and, when the lost motion quantity exceeds
the predetermined value, the biasing force of the other biasing
member causes the limitation pin toward the direction of the
limitation purpose hole.
17. The variably operated valve system for the internal combustion
engine as claimed in claim 4, wherein an angle which is a
subtraction of 90.degree. from an angle formed between the
corresponding one of the pair of swing arms and the one of the pair
of fulcrum members when the lost motion quantity of the fulcrum
member is at the predetermined value is smaller than an angle
formed between the corresponding one of the pair of swing arms and
the one of the pair of fulcrum members when the engine valves are
open at a time of a maximum lift control.
18. The variably operated valve system for the internal combustion
engine as claimed in claim 4, wherein the valve stop inhibiting
means includes a limitation member that limits the lost motion by
biasing the one of the pair of fulcrum members toward a direction
of the corresponding one of the pair of swing arms, when the lost
motion quantity of the one of the pair of fulcrum members exceeds
the predetermined value.
19. The variably operated valve system for the internal combustion
engine as claimed in claim 14, wherein the valve stop inhibiting
means includes a valve stop inhibit circuit constituted by a
control unit that interrupts the supply of the hydraulic pressure
via an electromagnetic switching valve of the hydraulic pressure
circuit.
20. The variably operated valve system for the internal combustion
engine as claimed in claim 19, wherein the predetermined value of
the lost motion quantity can arbitrarily be set according to a
driving condition of the engine.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a variably operated valve
system for an internal combustion engine which is capable of
performing a variable control of a valve lift quantity of an engine
valve (one or each of a pair of a pair of engine valves per engine
cylinder) and performing a valve stop.
[0003] (2) Description of Related Art
[0004] A Japanese Patent Application First Publication (tokkai) No.
2010-007636 published on Jan. 14, 2010 exemplifies a previously
proposed variably operated valve system for an internal combustion
engine.
[0005] The previously proposed variable valve system disclosed in
the above-described Japanese Patent Application First Publication
includes a variable mechanism which continuously varies lift
quantities and working angles of two intake valves per cylinder and
a stop mechanism which stops open-and-closure operations of one of
the two intake valves. In a commonly used driving range, one of the
two intake valves is made lost motion to stop the one intake valve
so that only the other of the two intake valves is driven to
strengthen an intake swirl, thereby a fuel consumption and a
combustion performance being improved. On the other hand, in a
driving range requiring an engine torque, the two intake valves are
driven and the working angles of both of the two intake valves are
made substantially equal to each other so that an intake air
charging efficiency can be improved.
[0006] Then, in a case where the required engine torque is
increased in a one-valve driving state, the one-valve driving state
is maintained and the working angle (or the lift quantity) is
increased if this required engine torque is smaller than a maximum
torque in the one-valve driving.
SUMMARY OF THE INVENTION
[0007] However, in the previously proposed variably operated valve
system, as described before, the one-valve driving state is
maintained if the required engine torque is smaller than the
maximum torque in the one-valve driving. Therefore, the working
angle of one of variably operated valve mechanisms in which the
related valve is stopped is forced to be expanded, in other words,
the lift quantity and a lost motion quantity are forced to be
large.
[0008] Therefore, an excessive load is applied onto a posture of
the one of the variably operated valve mechanisms in which the
related valve is stopped so that a space between one end section of
one of swing arms via which the one intake valve is
open-and-closure operated and a pivot which provides a swing
fulcrum of the one swing arm becomes non-uniform or becomes a local
contact. Then, a positional gap between both of the one end section
and the pivot occurs and, in some cases, there is a possibility of
a dropping out of the one end section of the swing arm from the
pivot.
[0009] It is, with the above-described problem in the previously
proposed variably operated valve system in mind, an object of the
present invention to provide a variable operated valve system which
is capable of suppressing an irregular behavior such as the
positional gap and drop out of the swing arm with respect to the
pivot by inhibiting a valve stop control in a case where the lost
motion quantity (a stroke quantity) of the valve stop mechanism
during the one-valve stop state exceeds a predetermined value.
[0010] According to one aspect of the present invention, there is
provided a variably operated valve system comprising: a drive shaft
to which a rotation driving force is transmitted from an engine
crankshaft and on an outer periphery of which drive cams are
disposed; two swing cams that operate two engine valves per engine
cylinder to open against spring forces of respective valve springs;
a transmission mechanism that converts rotation motions of the
drive cams into swing motions and transmits the converted swing
motions to the respective swing cams; a pair of swing arms
interposed between the respective swing cams and the respective
engine valves to operate the respective engine valves to open or
close; a pair of fulcrum members each of which provides a swing
fulcrum of each of the swing arms; a control mechanism that varies
a posture of the transmission mechanism to variably control a lift
quantity of each of the engine valves; a valve stop mechanism that
makes at least one of the pair of fulcrum members lost motion to
stop open-and-closure drives for one of the two engine valves; and
valve stop inhibit means for inhibiting a stop of open-and-closure
drives for the one of the engine valves, in a case where a lost
motion quantity of the valve stop mechanism exceeds a predetermined
value.
[0011] According to another aspect of the present invention, there
is provided a variably operated valve system for an internal
combustion engine, comprising: drive cams to which a rotational
force is transmitted from a crankshaft; engine valves, two of the
engine valves being mounted in each of engine cylinders and each
engine valve being biased toward a valve closure direction by means
of a spring force of a corresponding one of valve springs; swing
cams that make the respective engine valves open operation against
spring forces of valve springs; a transmission mechanism that
converts rotation motions of the drive cams into swing motions and
transmits the converted swing motions to the swing cams; a control
mechanism that varies a posture of the transmission mechanism to
variably control a lift quantity of each of the engine valves; a
pair of operational members that swing in accordance with the swing
motions of the swing cams to operate the respective engine valves
to open or close; a valve stop mechanism that absorbs a swing
quantity of one of the pair of operational members to stop
open-and-closure operations of one of the two engine valves; and
valve stop inhibiting means for inhibiting an absorption of a swing
motion of the valve stop mechanism in a case where the swing
quantity of each of the pair of the operational members exceeds a
predetermined quantity.
[0012] According to a still another aspect of the present
invention, there is provided a variably operated valve system for
an internal combustion engine, comprising: a drive cam rotationally
driven through a crankshaft; a pair of engine valves, each engine
valve being biased toward a closure direction by means of a spring
force of a valve spring; a pair of swing cams that swing to drive
the pair of engine valves via a pair of operational members; a
transmission mechanism that converts a rotation motion of the drive
cam into a swing motion and transmits the converted swing motion to
the pair of swing cams; a control mechanism that varies a posture
of the transmission mechanism to vary operation characteristics of
the pair of the engine valves; and a valve stop mechanism disposed
on at least one of the pair of operational members to make a lost
motion to stop a drive of one of the pair of engine valves,
wherein, in a case where a valve lift quantity of one of the pair
of engine valves exceeds a predetermined value, an operation of a
valve stop through the valve stop mechanism is inhibited.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a perspective view representing a first preferred
embodiment of a variably operated valve system according to the
present invention which is applicable to one bank side of a V
shaped six cylinder internal combustion engine.
[0014] FIG. 2 is a cross sectional view of the variably operated
valve system cut away along a line A to A shown in FIG. 1.
[0015] FIG. 3 is a cross sectional view of the variable operated
valve system cut away along a line B to B shown in FIG. 1.
[0016] FIGS. 4A and 4B are a longitudinal cross sectional view
representing a first hydraulic pressure rush adjuster in the first
preferred embodiment shown in FIG. 1 and a longitudinal cross
sectional view representing an action of the first hydraulic
pressure rush adjuster.
[0017] FIG. 5 is a longitudinal cross sectional view of a second
hydraulic pressure rush adjuster in the first preferred embodiment
shown in FIG. 1 according to the present invention.
[0018] FIG. 6 is a rough configuration view representing a control
hydraulic pressure circuit in the first embodiment shown in FIG.
1.
[0019] FIG. 7A is an explanatory view for explaining an action of
the first hydraulic pressure rush adjuster at a time of a valve
closure in a case where a valve lift quantity of an intake valve in
the first embodiment is controlled to L2 and FIG. 7B is an
explanatory view for explaining an action of the first hydraulic
pressure rush adjuster at a time of open of the intake valve in the
case where the valve lift quantity of the intake valve in the first
embodiment is controlled to L2.
[0020] FIG. 8A is an explanatory view for explaining an action of
the second hydraulic pressure rush adjuster at a time of a valve
closure in a case where a valve lift quantity of an intake valve in
the first embodiment is controlled to L2 and FIG. 8B is an
explanatory view for explaining an action of the second hydraulic
pressure rush adjuster at a time of open of the intake valve in the
case where the valve lift quantity of the intake valve in the first
embodiment is controlled to L2.
[0021] FIG. 9 is an explanatory view for explaining an action of
the first hydraulic pressure rush adjuster in a case where a state
transition is made from a state in which the lift quantity is
controlled to L3 to a state in which a valve stop control is
carried out.
[0022] FIG. 10A is an explanatory view for explaining an action of
the first hydraulic pressure rush adjuster at the time of the valve
closure in a case where the lift quantity of the intake valve in
the first embodiment is controlled to a maximum lift quantity (L7)
and FIG. 10B is an explanatory view for explaining the action of
first hydraulic pressure rush adjuster at the time of the valve
open in the case where the lift quantity of the intake valve in the
first embodiment is controlled to the maximum lift quantity
(L7).
[0023] FIG. 11A is an explanatory view for explaining an action of
the second hydraulic pressure rush adjuster at the time of the
valve closure in a case where the lift quantity of the intake valve
in the first embodiment is controlled to the maximum lift quantity
(L7) and FIG. 11B is an explanatory view for explaining the action
of the second hydraulic pressure rush adjuster at the time of the
valve open in the case where the lift quantity of the intake valve
in the first embodiment is controlled to the maximum lift quantity
(L7).
[0024] FIG. 12 is a graph representing the lift characteristic of
the intake valve in the first embodiment.
[0025] FIG. 13 is a characteristic graph representing a
relationship between a lost motion quantity of the first hydraulic
pressure rush adjuster and a rotation angle of a control shaft, in
the first embodiment.
[0026] FIG. 14 is a characteristic graph representing a
relationship between the lift quantity of the intake valve and the
rotation angle of the control shaft in the first embodiment.
[0027] FIG. 15 is a control flowchart executed by a control unit
used in the first embodiment shown in FIG. 1.
[0028] FIG. 16 is a rough configuration view representing the
control hydraulic pressure circuit in a second preferred embodiment
according to the present invention.
[0029] FIG. 17 is a longitudinal cross sectional view representing
the first hydraulic pressure rush adjuster in a third preferred
embodiment according to the present invention.
[0030] FIG. 18 is a longitudinal cross sectional view representing
the second hydraulic pressure rush adjuster in a fourth preferred
embodiment according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Hereinafter, preferred embodiments of a variably operated
valve system for an internal combustion engine according to the
present invention will be described on a basis of attached drawings
in order to facilitate a better understanding of the present
invention. In these embodiments, the present invention is applied
to a V shaped six cylinder internal combustion engine and the
variably operated valve system includes a variable mechanism which
variably controls working angles and valve lifts (quantities) of
intake valves which are engine valves. A right bank includes a
first cylinder #1, a third cylinder #3, and a fifth cylinder #5 and
a left bank includes a second cylinder #2, a fourth cylinder #4,
and a sixth cylinder #6. However, the right bank and the left bank
have mutually the same structure. Hence, hereinafter, only one side
bank, namely, the right bank will be described.
First Embodiment
[0032] FIGS. 1 through 3 show a first preferred embodiment of the
variably operated valve system according to the present
invention.
[0033] The variably operated valve system includes: first and
second intake valves 3, 3 per (one) cylinder which open or closes a
pair of intake ports formed within a cylinder head 1; a drive shaft
5 disposed at an upper side of first cylinder #1, third cylinder
#3, and fifth cylinder #5 along a forward-or-backward direction of
the engine and having three drive cams 5a on an outer periphery of
drive shaft 5; a pair of swing cams 7, 7 rotatably supported on an
outer peripheral surface of drive shaft 5 to make the respective
intake valves 3, 3 open-and-closure operation via respective swing
arms 6, 6 which are operational members; a transmission mechanism 8
which converts a rotational force of respective swing cams into a
swing force and transmits the converted swing force to respective
swing cams 7, 7; a control mechanism 9 which controls working
angles and lift quantities of respective intake valves 3, 3 via
transmission mechanism 8; first and second hydraulic pressure rush
adjusters 10a, 10b which are two fulcrum members (pivots) to make a
valve clearance between each intake valve 3, 3 and each swing cam
7, 7 via each swing arm 6 zero-rush; and three valve stop
mechanisms 11, each valve stop mechanism 11 stopping the
open-and-closure operations of one (first intake valve) of the two
intake valves 3 via one side first hydraulic pressure rush adjuster
10a in accordance with an engine driving condition.
[0034] It should be noted that drive shaft 5, swing cam 7,
transmission mechanism 8, and control mechanism 9 constitute a
variable mechanism.
[0035] Hereinafter, for explanation conveniences, each structural
member in a single cylinder, for example, in first cylinder #1 will
be described below.
[0036] Each intake valve 3 is slidably held on a cylinder head 1
via a valve guide 4 and is biased toward a closure direction by
means of each valve spring 12 elastically contacted between each
spring retainer 3b disposed adjacently to each stem end 3a and an
upper surface of the inner part of cylinder head 1.
[0037] Drive shaft 5 has swing cam 7 which is rotatably supported
on a plurality of bearing sections 13 mounted on an upper end
section of cylinder head 1 and to which a rotational force of an
engine crankshaft is transmitted via a timing belt disposed on one
end section of drive shaft 5. A drive cam 5a per cylinder is
disposed on the outer periphery of drive shaft 5 has an axial
center X eccentrically disposed in a radial direction from an axial
center Y of drive shaft 5 and has a cam profile on an outer
periphery thereof formed substantially in an ordinary circular
shape.
[0038] A recessed lower surface of one end section 6a of each swing
arm 6 is contacted on a stem end 3a of each intake valve 3 and a
lower surface recess section 6c of the other end section 6b is
contacted on each of first and second hydraulic pressure rush
adjusters 10a, 10b and a roller 14 is rotatably housed in a housing
hole formed on a center section of each swing arm 6 via a roller
shaft 14a.
[0039] Each swing cam 7 is, as shown in FIG. 1, integrally
installed at both ends of a cylindrical camshaft 7a and a cam
surface 7b including a base circle surface, a ramp surface, and a
lift surface is formed on a lower surface of each swing arm 7 and
the base circle surface, the ramp surface, and the lift surface are
rollably contacted on an upper surface of roller 14 of each swing
arm 6 in accordance with a swing position of swing cam 9.
[0040] Camshaft 7a has a journal section which is formed on an
axially substantial center position of an outer peripheral surface
of cam shaft 7a and is rotatably supported on journal sections 13
with a minute clearance and has an inner peripheral surface
rotatably supporting an outer peripheral surface of drive shaft
5
[0041] Transmission mechanism 8 includes a rocker arm 15 arranged
on an upper side of drive axle 5; a link arm 16 which links between
one end section 15a of rocker arm 15 and drive cam 5a; and a link
rod 17 which links between the other end section 15b of rocker arm
15 and one swing cam 7.
[0042] Rocker arm 15 has: a cylindrical base section at a center
section of rocker arm 15 which is rotatably supported on a control
cam, as will be described later; one end section 15a rotatably
linked to link arm 16 by means of a pin 18; and the other end
section 15b rotatably linked to an upper end section of link rod 17
via a pin 19.
[0043] Link arm 16 has a fitting hole 16a provided on a center
position of an annular base section of link arm 16 to which a cam
main body of drive cam 5a is rotatably fitted and has a projection
end linked to one end section 15a of rocker arm by means of pin
18.
[0044] It should be noted that a lower end section of link rod 17
is rotatably linked to a cam nose section of swing cam 7 via pin
20.
[0045] It should also be noted that an adjuster mechanism 23 which
minutely adjusts the lift quantity of each intake valve 3 during an
assembly of structural parts is interposed between the other end
15b of rocker arm 15 and the upper end of link rod 17.
[0046] On control mechanism 9, a control shaft 21 rotatably
supported on the same journal section at the upper position of
drive shaft 5 and a control cam 22 which is provided on the outer
periphery of control shaft 21, is slidably fitted into a supporting
hole pf rocker arm 15, and provides a swing fulcrum of rocker arm
15 are fixed onto control mechanism 9.
[0047] Control shaft 9 is disposed in parallel to drive shaft 5 in
the engine forward-or-backward direction and rotatably controls
actuator 50 shown in FIG. 6. On the other hand, control cam 22 has
an axial center position eccentrically deviated from the axial
center of control shaft 21 by a predetermined distance.
[0048] Actuator 50, as shown in FIG. 6, includes: an electrically
driven motor 51 fixed to one end section of a housing (not shown);
and a ball screw mechanism 52 as a speed reduction mechanism which
disposed in the inside of the housing and transmits a rotational
drive force of electrically driven motor 51 to control shaft
21.
[0049] Electrically driven motor 51 is constituted by a DC motor of
a proportional type and is controlled to be normally or reversely
rotated by a control signal from a control unit 53 as will be
described later.
[0050] Each of first and second hydraulic pressure rush adjusters
10a, 10b, as shown in FIGS. 1 through 5, includes: a bottomed
cylindrical body 24 slidably held in an upward-or-downward
direction within a retaining hole is of cylinder head 1; a plunger
27 slidably housed within body 24 in the upward-or-downward
direction, having a partitioning wall 25 integrally provided at a
lower section of plunger 27, and having an inner section
constituting a reservoir chamber 26; a high pressure chamber 28
communicated with reservoir chamber 26 via a communication hole 25a
penetrated through partitioning wall 25; and a check valve 29
disposed in the inner section of high pressure chamber 28 to allow
the working oil within reservoir chamber 26 only in the direction
to high pressure chamber 28. In addition, an exhaust hole 1b
through which working oil reserved within retaining hole 1a is
exhausted externally is formed.
[0051] Body 24 has an outer peripheral surface on which a circular
first recess groove 24a is formed and a first passage hole 31
radially formed in the inner section of cylinder head 1. A
downstream end of first passage hole 31 communicates oil passage 30
opened to first recess groove 24a with the inner part of body
24.
[0052] In addition, body 24 at first hydraulic pressure rush
adjuster 10a side has a bottom section, as shown in FIGS. 4A and
4B, extended toward a more downward direction than body 24 at
second hydraulic pressure rush adjuster 10b and cylindrically
formed.
[0053] Oil passage 30 is communicated with a main oil gallery 31a
for a lubricating oil supply formed within cylinder head 1 and
lubricating oil is supplied under pressure into main oil galley 31a
from an oil pump 54 shown in FIG. 6.
[0054] A cylindrical second recess groove 27a is formed on an outer
peripheral surface at a substantially center section in the axial
direction of plunger 27 and a second passage hole 32 which
communicates first passage hole 31 with reservoir chamber 26 is
penetrated through a peripheral wall of second recess groove 27a
along the radial direction. In addition, a tip surface of a tip
head section 27b is formed in a spherical (surface) shape in order
to secure a favorable sliding characteristic on a lower surface
recess section 6c of the other end section 6b of corresponding one
of swing arms 6, 6.
[0055] It should be noted that a maximum projection quantity of
plunger 27 is limited by means of a stopper member 33 fitted and
fixed onto an upper end section of body 24.
[0056] An axial length of second recess groove 27a is relatively
largely formed so that first passage hole 31 and second passage
hole 32 are, at all times, communicated with each other regardless
of whether any upward-or-downward sliding position is taken by
plunger 27 with respect to body 24.
[0057] Check valve 29 includes: a check ball 29a which opens or
closes a lower section opening edge of communication hole 25a; a
cup-shaped retainer 29c which retains a first coil spring 29b; and
a second coil spring 29d which biases whole plunger 27 while
biasing retainer 29c in the direction of partitioning wall 25.
[0058] Then, at a base circle interval of swing cam 7, high
pressure chamber 28 provides a low pressure along with an advance
movement of plunger 27 (upward movement) by a biasing force through
second coil spring 29d. At this time, a working oil supplied from
into retaining hole is caused to flow into reservoir chamber 26 via
second recess groove 27a and second passage hole 32, presses check
ball 29a to open against the spring force of first coil spring 29b
so that the working oil is caused to flow within high pressure
chamber 28.
[0059] Plunger 27, at all times, pushes other end section 6b of
swing arm 6, a gap among swing cam 7, one end section 6a of swing
arm 6, and stem end 3a of each intake valve 3 is adjusted to
zero-rush via a contact between roller 14 and swing cam 7.
[0060] Then, at the lift interval of swing cam 7, downward load is
acted upon plunger 27. Hence, the hydraulic pressure within high
pressure chamber 28 is raised and oil within high pressure chamber
28 leaks out from a gap between plunger 27 and body 24 so that
plunger 27 is slightly dropped (leak down).
[0061] At the next (again) base circle interval of swing cam 7, as
described above, the gap between each part is adjusted to provide a
zero rush due to an advance movement (upward motion) of plunger 27
by means of a biasing force of second coil spring 29d.
[0062] The rush adjustment function as described above is provided
in both of first and second hydraulic pressure rush adjusters 10a,
10b.
[0063] Valve stop mechanism 11 is, as shown in FIGS. 4A and 4B,
disposed only at first hydraulic pressure rush adjuster 10a. Valve
stop mechanism 11 includes: a cylindrical sliding purpose hole 34
continuously formed at a bottom side of retaining hole 1a; a lost
motion spring 35 which biases first hydraulic pressure rush
adjuster 10a toward the upward direction; and a limitation
mechanism 36 which limits a lost motion of first hydraulic pressure
rush adjuster 10a.
[0064] Sliding purpose hole 34 has an inner diameter set at the
same length as the inner diameter of retaining hole 1a and is
arranged such that body 24 is slidably and continuously held in the
upward-or-downward direction from retaining hole 1a.
[0065] Lost motion spring 35 is formed of a coil spring and biases
the bottom surface of body 24 in the upward direction so that tip
end section 27a of plunger 27 is elastically contacted on the lower
surface of the other end section 6b of swing arm 6.
[0066] In addition, a maximum upward movement position of body 24
is limited by means of stopper pin 17 inserted and arranged through
an inside of cylinder head 1. That is to say, stopper pin 37 is
disposed in the axial right angle direction toward body 24 within
cylinder head 1 and tip section 37a of stopper pin 37 is slidably
disposed in the axial right angle direction within first recess
groove 24a. Then, a maximum upward sliding position of body 24 is
limited by a contact of tip section 37a along with the upward
movement of body 24 on the lower end edge of first recess groove
24a.
[0067] Therefore, first hydraulic pressure rush adjuster 10a
carries out the lost motion by stroking in the upward-or-downward
direction between retaining hole 1a and sliding purpose hole 34 via
a spring force of lost motion spring 35 along with the swing motion
of swing arm 6 so that a function of swing arm as the swing fulcrum
is lost and the open-and-closure operations of first intake valve 3
is stopped.
[0068] Limitation mechanism 36 mainly includes: a movement purpose
hole 38 penetrated in the inner diameter direction of bottom
section 24b of body 24; a limitation purpose hole 39 formed in the
axial right angle direction to retaining hole is of cylinder head
1; a retainer 40 fixed to one end side of the internal of movement
purpose hole 38; a limitation pin 41 slidably disposed in the
inside of movement purpose hole 38 and movable from movement
purpose hole 38 to limitation purpose hole 39; and a return spring
42 elastically disposed between a rear end of limitation pin 41 and
retainer 40 to bias limitation pin 41 toward limitation purpose
hole 39.
[0069] Limitation purpose hole 39 is made coincident with movement
purpose hole 38 from the axial direction when body 34 is limited to
the maximum upward direction by means of stopper pin 37. An inner
diameter of limitation purpose hole 39 is formed at substantially
the same as movement purpose hole 38 and a signal hydraulic
pressure is introduced from an oil passage hole 43 formed within
cylinder head 1 at one end side of limitation purpose hole 39.
[0070] It should be noted that the limitation of body 24 in the
rotational direction can easily be realized by slightly increasing
a jump out quantity (projection quantity) of stopper pin 37,
providing an elongated slit within first recess groove 24a of body
24, and by engaging the elongated slit with the tip of stopper pin
37. Or alternatively, a separate rotation limitation member may be
equipped between cylinder head 1 and body 24.
[0071] Retainer 40 is formed in a bottomed cylindrical shape and
has a breathing hole 40a penetrated through a bottom section of
retainer 40 to secure a smooth movement of limitation pin 41. In
addition, an axial length of retainer 40 is set to a length such
that a rear end of limitation pin 41 is contacted on a tip end edge
of retainer 40 and a further retractable movement of limitation pin
41 is limited at a time point at which limitation pin 41 is
completely housed within movement purpose hole 38, as shown in FIG.
4B.
[0072] Limitation pin 41 is formed in an approximately hollow
cylindrical shape, an outer diameter is slightly smaller than
movement purpose hole 38 and an inner diameter of a limitation
purpose hole 39 so that a smooth slidability (a smooth sliding
motion) is secured. In addition, this limitation pin 41 receives
the hydraulic pressure supplied from oil passage hole 43 to
limitation purpose hole 39 by a pressure receiving surface of tip
section 41a so that a retractable movement against the spring force
of return spring 42 is carried out, the tip section of limitation
pin 41 is dropped out from limitation purpose hole 39 and housed
within movement purpose hole 38 and the limitation is released.
[0073] The hydraulic pressure supplied under pressure from oil pump
54 is supplied to oil passage hole 43 (limitation purpose hole 39)
6 via an electromagnetic switching valve 55 as a signal hydraulic
pressure as shown in FIG. 6.
[0074] Electromagnetic switching valve 55 switches a spool valve
slidably disposed in the inside of the valve body (not shown) at
two stages in an on-or-off manner by means of an electromagnetic
force of a solenoid thereof and a spring force of a coil spring
thereof. A control current is supplied or not supplied from a
control unit 53 which controls a drive of electrically driven motor
51 to the solenoid so that a switching control such that a pump
draining passage and oil passage hole 43 are communicated or the
pump draining passage is closed to communicate oil passage hole 43
with a drain passage 44 is carried out. Thus, the signal hydraulic
pressure is controlled in two stages of large and small.
[0075] Control unit 53 detects an engine driving state (or an
engine driving condition) on a basis of information signals from
various sensors such as a crank sensor, an airflow meter, coolant
temperature sensor, a throttle valve angle sensor, and so forth and
controls a rotational position of control axis 21 by drivingly
controlling electrically driven motor 51 in response to the
information signal from a rotational position sensor (not shown)
which detects the present rotational position of control shaft 21.
Thus, lift quantities and working angles of respective intake
valves 3, 3 are varied.
[0076] In addition, this control unit 53 includes a valve stop
inhibit circuit which is valve stop inhibiting means for inhibiting
the lost motion of valve stop mechanism 11 via electromagnetic
switching valve 55. This valve stop inhibit circuit performs such a
control that oil passage hole 43 is communicated with drain passage
44 via electromagnetic switching valve 55 on a basis of a rotation
angle .theta. of control shaft 21. This causes limitation pin 41 to
move toward a direction of limitation purpose hole 39 by means of
the spring force of return spring 42 and tip end section 41a of
limitation pin 41 is engageably inserted into limitation purpose
hole 39. Thus, body 24 (first hydraulic pressure rush adjuster 10a)
is locked to cylinder head 1 and the lost motion of first hydraulic
pressure rush adjuster 10a is inhibited.
[0077] The rotation angle position of control shaft 21 to control
the drive of electromagnetic switching valve 55 by means of the
valve stop inhibit circuit can arbitrarily be set in accordance
with an engine driving state or so forth. In the first embodiment,
the rotation angle position is .theta.3 for which control shaft 21
provides in such a way that the lift quantity becomes L3 shown in
FIG. 12.
[0078] In other words, in a case where that the lift quantity of
first intake valve 3 exceeds L3, this lift quantity having a
proportional relationship to the stroke quantity of the lost motion
of first hydraulic pressure rush adjuster 10a, is detected by
rotational angle .theta. of control shaft 21 and, at this time
point, intake valves 3, 3 is in the valve stop state, the control
current flowing toward electromagnetic switching valve 55 is
interrupted to communicate oil passage hole 43 with drain passage
44 so that limitation pin 41 forcibly locks first hydraulic
pressure rush adjuster 10a. It should be noted that if, at a time
point at which the lift quantity of first intake valve 3 exceeds
L3, limitation pin 41 is already locked and the state is in a
two-valve lift operation state, this state is maintained.
[Operation of Variably Valve Operated System]
[0079] Hereinafter, an operation of the variably operated valve
system in the above-described first embodiment will be
explained.
[0080] For example, when the engine is driven in a range from an
idling state to a low rotation region, electrically driven motor 51
is rotationally driven by means of a control current outputted from
control unit 53. This rotational torque is transmitted to control
shaft 21 via ball screw mechanism 52. When this control shaft 21 is
rotationally driven in one direction, as shown in FIGS. 7A, 7B, 8A,
and 8B, control cam 22 is uni-directionally pivoted so that an
axial center of control cam 22 is rotated around the axial center
of control shaft 21 at the same radius and a wall thickness section
of control cam 22 is spaced apart from drive shaft 5 and moved
toward a right upper direction as shown in FIGS. 7A through 8B.
Thus, the other end section 15b of rocker arm 15 and a pivot point
(linkage pin 19) of link rod 17 are moved in the upper direction
with respect to drive shaft 5 and, thus, the cam nose section side
of each swing cam 7 is forcibly lifted via link rod 17.
[0081] Thus, when drive cam 5a is rotated and pushes up one end
section 15a of rocker arm 15 via link arm 16, the lift quantity of
rocker arm 15 is transmitted to each swing cam 7 and each swing arm
6 via link rod 17 so that each intake valve 3 is open against the
basing spring of valve spring 12 and the lift quantity of each
intake valve 3 becomes sufficiently small as L1 through L3 shown in
FIG. 12.
[0082] For example, in a case where the engine driving state is
transferred from the low engine speed range to a middle or high
engine speed range, the control current causes electrically driven
motor 51 to reversely be rotated so that ball screw mechanism 52 is
rotated in the same direction. As shown in FIGS. 10A, 10B, 11A, and
11B, control shaft 21 causes control cam 22 to be rotated in the
other direction and the axial center of control cam 22 is moved
toward the downward direction.
[0083] Thus, whole rocker arm 15 is, at this time, moved toward the
direction of drive axle 5 so that the other end section 15b of
rocker arm 15 presses a cam nose section of swing cam 7 in the
downward direction via link rod 17 so that a whole of each swing
cam 7 is pivoted in a counterclockwise direction by a predetermined
quantity from a position shown in FIGS. 7A through 8B. Hence, as
shown in FIGS. 10A through 11B, a contact position of cam surface
7b of each swing cam 7 to an outer peripheral surface of roller 14
is moved toward the cam nose side (lift section side).
[0084] Therefore, when drive cam 5a is rotated at a time of valve
open of intake valve 3 so as to push up one end section 15a of
rocker arm 15 via link arm 16, each intake valve 3 is opened
against the spring force of each valve spring 12 via each swing arm
6. The valve lift quantity of each intake valve 3 is continuously
varied up to a maximum of L7 shown in FIG. 12 and becomes large
from L4 to L7 as the rotation of drive cam 5a is increased.
Therefore, an intake air charging efficiency is improved and an
improvement in the output can be achieved.
[Operation of Valve Stop Mechanism]
[0085] Then, in a case where the lift quantity of each intake valve
3, 3 in the engine driving state of the idling state and the low
engine speed area becomes a small lift quantity range of L1 through
L3 shown in FIG. 12, especially, in a particular engine driving
state in which an improvement of fuel economy is achieved, the
control current is outputted to electromagnetic switching valve 55
from control unit 53 and, thus, a large discharge hydraulic
pressure is introduced from oil pump 54 to limitation purpose hole
39 via oil passage hole 43 as the signal hydraulic pressure.
[0086] Limitation pin 41 on which this large signal hydraulic
pressure is moved toward the backward direction (or retracted)
against the spring force of return spring 42 so that tip end
section 41a of return spring 41 is slipped out from limitation
purpose hole 39 so that a lock of first hydraulic pressure rush
adjuster 10a to cylinder head 1 is released.
[0087] Hence, first hydraulic pressure rush adjuster 10a, as shown
in FIG. 4B, the whole of first rush adjuster 10a can make the lost
motion and the upward-or-downward movement within retaining hole 1a
and sliding purpose hole 34 is repeated via the spring force of
lost motion spring 35 and first hydraulic pressure rush adjuster
10a enters the lost motion state. Hence, first intake valve 3 is in
the valve closure state (valve stop state).
[0088] That is to say, until the valve is in the valve stop state,
swing cam 7 is varied from a zero-lift position (valve closure)
shown in FIG. 7A to a maximum valve open lift position shown in
FIG. 7B.
[0089] Suppose that each intake valve 3, 3 is opened by a lift
quantity of L2. Even if, in the valve stop state, swing cam 7 is
maximally swung, first hydraulic pressure rush adjuster 10a makes
the lost motion by stroke quantity M2 shown in FIG. 7B and,
actually, the state of the engine is transferred to the valve stop
state in which not valve lift is carried out. An instantaneous
opening angle formed between first swing arm 6 and first hydraulic
pressure rush adjuster 10a is .alpha. (refer to FIG. 7B). This
.alpha. indicates .beta.7 shown in FIG. 10B when swing cam 7 is
placed at position indicating a peak lift (maximum lift control)
but this opening angle does not give an excessive opening
angle.
[0090] Hence, even if swing cam 7 indicates the peak lift (maximum
valve open operation), a smooth valve stop operation can be
obtained.
[0091] On the other hand, second hydraulic pressure rush adjuster
10b functions as an ordinary swing fulcrum to second swing arm 6 as
shown in FIGS. 8A and 8B. Hence, second intake valve 3 still
carries out the open-and-closure operations at lift quantity of L2.
Thus, the intake air swirl is reinforced and the improvements in
the fuel economy and combustion can be achieved.
[0092] Next, consider such a case where the engine speed is,
furthermore, increased, the required torque is increased, the
engine valve is again transferred to the two-valve lift operation
state, and the lift quantity is increased so that control shaft 21
is rotated in the clockwise direction to provide .theta.3 of
rotation angle, namely, a case where the lift quantities of both of
intake valves 3, 3 indicate L3 shown in FIG. 12. Suppose a case
when the requirement (request) of fuel economy is again increased
from this state and the engine driving state is transferred to the
valve stop state. In this case shown in FIG. 9, the opening angle
formed between first swing arm 6 and first hydraulic pressure rush
adjuster 10a is considerable open as .alpha.3.
[0093] Therefore, a contact of tip end head section 27b of first
hydraulic pressure rush adjuster 10a on lower surface recess
section 6c of first hydraulic pressure rush adjuster 10a becomes
uniform.
[0094] That is to say, tip end head section 27b of first hydraulic
pressure rush adjuster 10a, ordinarily, stably holds lower surface
recess section 6c of the other end section 6b of first swing arm 6
while the contact of tip end head section 27b on a spherical
surface section at the lost motion 4 side and the contact of tip
end head section 27b on the spherical surface section at an
anti-roller 14 are balanced. However, when opening angle of
.theta.3 becomes wide (large), the contact on the spherical surface
section of roller 14 side is moved toward the upward direction and
the contact section of the spherical surface section at the
anti-roller side is moved in the downward direction.
[0095] If a weight (load) from roller 14 acted upon first swing arm
6, the load received at the contact section of the spherical
surface section of roller side 14 moved in the upward direction is
extremely increased. Thus, the balance is broken and it easily
becomes a local contact.
[0096] Consequently, in addition to the contact section to move in
the upward direction, a positional gap on the contact section due
to the load of roller 14 is easily generated. Hence, a phenomenon
such that first swing arm 6 is deviated toward an anti-valve side
(toward away from the intake valves 3, 3) and, dependent upon the
situation, there is a possibility that lower surface recess section
6c of the other end section 6b of first swing arm 6 becomes out of
place from tip end head section 27b. However, at the level of this
.alpha.3, the fact that lower surface recess section 6c of the
other end section 6b which becomes out of place (deviated from) tip
head section 27b falls one way or another an allowable range but if
it exceeds .alpha.3, there is increased possibility that actually
an deviation-out phenomenon described above is developed.
[0097] Therefore, at a time point at which the lift quantity is in
excess of lift quantity of L3, the valve stop inhibit circuit of
control unit 53 interrupts the cut off of the control current to
electromagnetic switching valve 55 so that oil passage hole 43 is
communicated with drain passage 44 so that the hydraulic pressure
within limitation purpose hole 39 and oil passage hole 43 is
exhausted toward an inside of an oil pan 45 (refer to FIG. 6) so
that the pressure within limitation purpose hole 39 is under a low
pressure state.
[0098] Thus, limitation pin 41 is moved in the direction of
limitation purpose hole 39 by means of the spring force of return
spring 42 so that first hydraulic pressure rush adjuster 10a at the
base circle range of swing cam 7 to move in the upward direction,
as shown in FIG. 4A, and stopper pin 37 and a further upward
movement is limited by stopper pin 27. At a time point at which
movement purpose hole 38 and limitation purpose hole 39 are made
coincident with each other, tip end section 41a of limitation pin
41 is inserted and engaged with limitation purpose hole 39 so that
first hydraulic pressure rush adjuster 10a is locked to cylinder
head 1.
[0099] Hence, the lost motion of first hydraulic pressure rush
adjuster 10a is limited at this time point.
[0100] A dot-and-dash line shown in FIG. 13 represents a
correlation between rotation angle .theta. of control shaft 21 and
a lost motion quantity (stroke length M) in a case where the valve
is stopped and a broken line shown in FIG. 14 represents a
correlation between rotation angle .theta. of control shaft 21 and
lift quantity L of intake valve 3 in a case where the lift
operation is carried out.
[0101] That is to say, as shown in FIG. 13, the correlation is
provided between lost motion quantity (stroke, length M) in a case
where the valve is stopped and rotation angle .theta. of control
shaft 21. As shown in FIG. 14, the correlation is provided between
rotation angle .theta. of control shaft 21 and lift quantity L of
intake valve 3. Hence, control unit 53 forcibly interrupts the
power supply to electromagnetic switching valve 55 at a time point
at which rotation angle of control shaft 21 exceeds .theta.3 on a
basis of the information signal from the rotation angle sensor.
[0102] The above-described series of operation is depicted as a
solid line of each of FIGS. 13 and 14. At a time point at which the
lost motion quantity exceeds M3, namely, at a time point at which
the lift quantity of first intake valve 3 exceeds L3, lost motion
operation of first hydraulic pressure rush adjuster 10a is
mechanically inhibited. Thus, together with second intake valve 3,
first intake valve 3 is open-and-closure operated and the engine
driving by means of both intake valves 3, 3 (two-valve driving) is
carried out.
[0103] Hence, at a time point at which the lift quantity of intake
valve 3 exceeds L3, the lost motion of first hydraulic pressure
rush adjuster 10a becomes eliminated (nullified or is not carried
out). Hence, the uniform and local contact between lower surface
recess section 6c at the other end section 6b of first swing arm 6
and tip end section 27b of plunger 27 of first hydraulic pressure
rush adjuster 10a and tip end head section 27b of plunger 27 of
first hydraulic pressure rush adjuster 10a can be avoided.
Therefore, lower surface recess section 6c of first swing arm 6 is,
for example, not dropped out from tip head section 27b of plunger
27 so that the smooth operation state can, at all times, be
obtained.
[0104] In addition, in a case where the engine speed is, for
example, further increased and fall in a region in which the lost
motion quantity of first hydraulic pressure rush adjuster 10a
further exceeds M3 (considerably larger than M3) (in a case where
the lift quantity of each of intake valves 3, 3 exceeds further L3
shown in FIG. 12, the non-power supply state from control unit 53
to electromagnetic switching valve 55 is continued so that the
signal hydraulic pressure is not introduced into limitation purpose
hole 39. Hence, the state in which no lost motion state of first
hydraulic pressure rush adjuster 10a is continued so that first
hydraulic pressure rush adjuster 10a exhibits the function as the
swing fulcrum in the same manner as second hydraulic pressure rush
adjuster 10b.
[0105] In other words, until the lost motion quantity of first
hydraulic pressure rush adjuster 10a indicates M3 (rotation angle
.theta. of control shaft 21 is .theta.3), first hydraulic pressure
rush adjuster 10a is allowed to be made the lost motion but, at the
time pint at which the lost motion quantity exceeds M3, the valve
stop is inhibited, the lost motion is limited and fixed, and first
hydraulic pressure rush adjuster 10a functions as the ordinary
swing fulcrum.
[0106] FIG. 15 shows a specific control flowchart executed by the
valve stop inhibit circuit of control unit 53.
[0107] That is to say, at a step S1, control unit 53 reads the
present engine driving state on a basis of the information signal
from the various kinds of sensors described above, at a step S2,
control unit 53 reads target lift quantities of first and second
intake valves 3, 3 in accordance with the engine driving state from
a preset control map, for example, a control map of the engine
speed and an engine load. Suppose now that the target lift quantity
of second intake valve 3 is L2, the target lift quantity of first
intake valve 3 is zero (the valve stop), and the present lift
quantities of first and second intake valves 3, 3 are the proximity
of L3.
[0108] At a step S3, control unit 53 determines whether target lift
quantity of first intake valve 3 of first hydraulic pressure rush
adjuster 10a side is zero or not. If zero, namely, the
determination of the valve stop is made, the routine goes to a step
S4. At this step S4, control unit 53 determines whether the actual
lift quantities of respective intake valves 3, 3 are equal to or
below L3 from rotation angle .theta. derived from the rotation
angle sensor of control shaft 21 and, in a case where the actual
lift quantities of respective intake valves 3, 3 are determined to
be equal to or below L3, the routine goes to a step S5.
[0109] At this step S5, control unit 53 carries out an output of an
on signal or continuation of the on signal to electromagnetic
switching valve 55. In other words, since the lift quantity is
equal to or below L3, the signal hydraulic pressure is supplied to
limitation purpose hole 39 and the valve state is transferred to
the lost motion of first hydraulic pressure rush adjuster 10a or
the lost motion is continued so that the valve is in one valve stop
state. (in the present case, the on signal is outputted to
electromagnetic switching valve 55 and the valve state is
transferred to the lost motion state.)
[0110] Thereafter, at a step S6, electrically driven motor 51 is
controlled toward the target lift quantity and a process in which
rotation angle .theta. of control shaft 21 is controlled is carried
out and the routine returns.
[0111] If, at step S3, target lift quantity of first intake valve 3
is determined not to be zero, or if, at step S4, the actual lift
quantities of respective intake valves 3, 3 are determined to
exceed L3, the routine goes to a step S7.
[0112] At step S7, control unit 53 carries out the process such
that the on signal is outputted to electromagnetic switching valve
55 or the on signal is continued (at the present case, the on
signal is continued).
[0113] In details, in a case where the actual lift quantities of
respective intake valves 3, 3 exceed L3, the supply of the signal
hydraulic pressure within limitation purpose hole 39 is interrupted
or the interruption is continued and limitation pin 41 is inserted
and engaged with limitation purpose hole 39 by means of the spring
force of return spring 42 or the insertion and engagement are
continued so that first hydraulic pressure rush adjuster 10a is
locked to cylinder head 1 or this lock is continued. Thus, for
first intake valve 3, the valve stop state is inhibited and the
open-and-closure operations (a lift operation) by means of first
swing arm 6 is carried out with first hydraulic pressure rush
adjuster 10a as the swing fulcrum. Hence, as described above, the
excessive lost motion of first hydraulic pressure rush adjuster 10a
is inhibited so that the irregular motion due to the local contact
of lower surface recess section 6c of the other end section 6b of
first swing arm on the tip head section 27b or so forth can be
avoided and a smooth operation state can be obtained.
[0114] It should be noted that, although, in the first embodiment,
a condition to forcibly inhibit the lost motion of first hydraulic
pressure rush adjuster 10a is when the lost motion exceeds M3 (when
the target lift of first intake valve 3 exceeds L3). However, it is
natural that, on the control map, the valve stop transition of
first intake valve 3 is not carried out even in the case of the
lower lift quantity than L3 and both of first and second intake
valves 3, 3 may be under a lift operation control.
[0115] For example, in a case where the engine is in a cold start
state in which a combustion torque overcoming an engine friction is
required even in a case of small working angle (for example, small
lift quantity L2), it is preferable to perform the open-and-closure
operations for two intake valves 3, 3 without the lost motion.
Hence, it is possible to inhibit the lost motion even if the list
quantity is below L3.
[0116] The time point at which lift quantity L3 or lost motion M3
is exceeded merely a reference to forcibly inhibit the lost motion.
However, the valve stop transition (transition to lost motion
operation) at the smaller lift quantity than L3 in the control map
is not carried out depending upon the driving condition but may be
carried out at the two-valve operation.
[0117] On the other hand, the setting of values of L3 or M3 which
provide a criterion to forcibly inhibit the lost motion described
above may be modified. For example, in the engine high speed range,
a slight separation between each component of the variably operated
valve mechanism is apt to occur. Hence, the irregular behavior such
as the positional gap or drop out of swing arm 6 with respect to
the pivot may furthermore be generated. Hence, the values of L3 and
M3 which provide the criterion described above may further be set
to smaller.
[0118] Hereinafter, merits of the first embodiment to the technique
of the previously proposed variably operated valve system described
in the Japanese Patent Application First Publication No.
2010-007636 described in the BACKGROUND OF THE INVENTION will
supplementary be described.
[0119] That is to say, in the previously proposed variably operated
valve system, as shown in FIG. 4 of the above-described Japanese
Patent Application first Publication, body (41) is housed and fixed
by means of cylinder head (11) and plunger itself (42) is in the
lost motion so that the valve stop is carried out.
[0120] Specifically, the lost motion quantity of plunger (42) is
increased by reducing the working oil acted upon the body to
perform the valve stop. In a midway through the reduction in the
working hydraulic pressure, the lost motion quantity is not
instantaneously increased and an instant at which an unstable
intermediate lost motion quantity is provided is present. In this
case, a lift curve is unstable, the motion of the variably operated
valve system is irregular, and it is not unprofitable for the
suppression of the irregular motion, and there is an anxiety of an
occurrence of a phenomenon such that the engine performance becomes
unstable.
[0121] Whereas, in the first embodiment, either of the lift
operation state or the valve stop state (lost motion state) is
selectively selected according to the engagement or the engagement
release by means of the limitation pin and no intermediate lift
curve is present. Hence, there is no anxiety described above.
[0122] In addition, the body (41) in the previously proposed
variable operated valve system is fixed to the cylinder head (11)
and the plunger itself (42) is made the lost motion. Hence, return
spring (45) to push up the plunger (42) serves as a spring function
(a minute stroke) to perform a rush adjustment of the hydraulic
pressure rush adjuster and a spring function (a large stroke) for
the plunger to make the lost motion. Hence, if the importance is
placed on the rush adjustment and the spring load is reversely
increased, the rush adjustment is not well performed an a pump up
phenomenon such that the plunger (42) excessively rises is
developed.
[0123] It should be noted that reference numerals described in
respective brackets denote those described in the above-identified
Japanese Patent Application First Publication.
[0124] Whereas, in the first embodiment, spring 29d to make the
rush adjustment and spring 35 for the lost motion can separately
and independently be set. Hence, there is no anxiety described
above.
[0125] In addition, in the previously proposed variable operated
valve system, when the working oil pressure (the working hydraulic
pressure) from the oil pump is low, as described above, the valve
state is in the valve stop state. Hence, at the time of an engine
cranking or engine start at which the hydraulic pressure from the
oil pump is not expected, the engine valve is in the valve stop
state. Therefore, an intake air quantity at the time of the engine
start becomes insufficient and a startability becomes worsened due
to an insufficient torque.
[0126] Whereas, in the first embodiment, as described before, in a
case where the signal hydraulic pressure is not acted, the valve
state is the two-valve operations. Thus, there is no anxiety of
worsening of the startability. A favorable startability can be
obtained.
Second Embodiment
[0127] FIG. 16 shows a second preferred embodiment of the variably
operated valve system in which, as the valve stop inhibiting means,
a mechanical structure is added.
[0128] A pair of oil holes 43a, 43b penetrated in the axial right
angle direction through control shaft 21 of bearing section 13
which journals (serves as a bearing for) control shaft 21 and are
formed on part of oil passage hole 43. On the other hand, a
communication hole 46 appropriately communicated with respective
oil holes 43a, 43b is penetrated and formed in the inside of
control shaft 21 in the axial right angle direction. Arc shaped oil
grooves 46a, 46b are formed on both end sections of this
communication hole 46.
[0129] This communication hole 46 serves to communicate both of oil
holes 43a, 43b of oil passage hole 43 via oil grooves 46a, 46b as
denoted by a solid line in FIG. 16 in a case where the rotation
angle position of control shaft 21 is .theta.2 (L2). In a case
where the rotation angle position of control shaft 21 indicates the
angle position exceeding .theta.3 (L3), as shown in the broken line
of FIG. 16, both of oil grooves 46a, 46b provide the positional gap
to interrupt the communication between both oil holes 43a, 43b.
[0130] Hence, in a case where the engine rotation (the engine
speed) falls in the low speed range and the revolution angle of
control shaft 21 falls in a range of .theta.1 through .theta.3 (L1
through L3 in each intake valve 3, 3), as denoted by the solid
line, oil passage 43 and communication hole 46 are communicated and
the signal hydraulic pressure is supplied within limitation purpose
hole 39. However, when the rotation angle gives a value exceeding
.theta.3 (L3), as denoted by a broken line in FIG. 16, closes both
oil holes 43a, 43b by the outer peripheral surface of control shaft
21 to interrupt mechanically the communication with oil passage
hole 43.
[0131] Therefore, the same effect and action as the first
embodiment can be obtained. Especially, in this embodiment, if
control unit 53 fails, electromagnetic switching valve 55 is
abnormally operated, and an abnormal signal hydraulic pressure is
supplied to the upstream side of oil passage hole 43, the passage
is interrupted by means of control shaft 21. Hence, if rotation
angle (lift quantity) exceeds L3 (L3), the lost motion of first
hydraulic pressure rush adjuster 10a is limited and the valve stop
is inhibited.
Third Embodiment
[0132] FIG. 17 shows a third preferred embodiment of the variably
operated valve system according to the present invention. A
bottomed cylindrical holding member 47 which is arranged for first
hydraulic pressure rush adjuster 10a to be slidable in the
upward-or-downward direction is press-fitted within retaining hole
1a of cylinder head 1 at first hydraulic pressure rush adjuster 10a
side and a projection section 47b is integrally disposed at a
center position of an inner surface of bottom wall 47a of holding
member 47.
[0133] A height of projection section 47b is set such that the
bottom surface of body 24 of first hydraulic pressure rush adjuster
10a is contacted on projection section 47b to limit the further
lost motion stroke, in a case where the lost motion quantity shown
in FIG. 13, in a slight degree, exceeds M3 when the first hydraulic
pressure rush adjuster 10a is made the lost motion.
[0134] It should be noted that a communication passage 47c which
communicates first recess groove 24a with oil passage 30 and a
breathing hole 47d at a bottom wall 47a side of holding member 47
are formed.
[0135] As described above, in the third embodiment, the lost motion
stroke of first hydraulic pressure rush adjuster 10a is
mechanically limited so that the excessive lost motion can be
suppressed. Hence, the local contact of first swing arm 6 on tip
head section 27b of plunger 27 can more accurately be avoided.
[0136] In addition, this holding member 47 is made of an iron
series material different from cylinder head 1 (ordinarily,
aluminum material). Thus, a wear and abrasion resistance such as
limitation purpose hole 39 which slides the limitation pin, sliding
purpose hole 34 which slides body 24 of first hydraulic pressure
rush adjuster 10a can be improved. As described above, holding
member 47 except projection member 47b can be applied to the first
embodiment.
Fourth Embodiment
[0137] FIG. 18 shows a fourth preferred embodiment of the variably
operated valve system according to the present invention.
[0138] A basic structure is the same as the first embodiment. The
whole lift quantity variable mechanism including respective swing
arms 7, 7 is arranged like a reflecting mirror in a reverse
direction as each embodiment.
[0139] Thus, swing cam 7 swings and lifts in a clockwise direction
shown in FIG. 18 so that swing arms 6, 6 and intake valves 3, 3 are
valve open lifted.
[0140] In this embodiment, as compared with the structure shown in
FIG. 9 in the first embodiment, the swing lift direction of swing
cam 7 is the same as the lost motion direction of first hydraulic
pressure rush adjuster 10a. Hence, the cam nose section of swing
cam 7 and swing arm 6 become difficult to be interfered during the
operation.
[0141] In addition, a contact point between swing cam 7 and roller
14 of swing arm 6 comes near to first hydraulic pressure rush
adjuster 10a side and just presses under pressure the vicinity to
the center of swing arm 6. A contact characteristic between first
hydraulic pressure rush adjuster 10a and swing arm 6 becomes
favorable and becomes difficult to remove. This is because, in tip
head section 27b of first hydraulic pressure rush adjuster 10a, the
contact at the spherical surface section at the roller section side
and the contact at the spherical surface section at the anti-roller
section side are balanced.
[0142] As described above, in the fourth embodiment, a favorable
contact state between first hydraulic pressure rush adjuster 10a
and swing arm 6 can be obtained and an interference between
respective components (parts) can be suppressed.
[0143] The present invention is not limited to this structure of
each of the preferred embodiments described above. For example, the
present invention is applicable to a V shaped eight cylinder engine
not only the V shaped six cylinder engine. The present invention is
also applicable to an inline four cylinder engine corresponding to
one bank of the V shaped cylinder engine, and another type
engine.
[0144] In addition, one of the two swing cams 7, 7 may have
different cam profiles and this achieves a combustion improvement
due to a slight swirl while the suction (intake) air charging
efficiency is maintained in a high engine load region in which both
of the (intake) valves are operated. In addition to intake valves
3, 3 as the engine valves, the present invention is applicable to
an exhaust valve side. In this alternative case, since the swirl of
exhaust gas can be reinforced, an exhaust emission transformation
performance at catalyst can be improved.
[0145] In addition, in each of the above-described embodiments,
from among the pair of engine valves, one of the pair of engine
valves is in the valve stop. However, the present invention is
applicable to a case where the two (pair of) engine valves are
valve stopped.
[0146] Furthermore, as the member which makes the lost motion, a
member having no rush function may be applied in addition to the
respective hydraulic pressure rush adjusters.
[0147] In addition, it is possible to dispose the valve stop
mechanism on first swing arm 6. In this case, a roller element
which can displace (make the lost motion) to a main swing arm, for
example, as disclosed in a Japanese Patent Application First
Publication (tokuhyou) No. 2010-270633 published on Dec. 2, 2010
(which corresponds to a U.S. Pat. No. 7,712,443 issued on May 11,
2010) and this roller element and main swing arm may be switched
between an engagement and a non-engagement. Even in this case, an
unusual posture such that the contact between the roller element
and the swing cam becomes out of place or becomes interfered or a
bottoming occurs at the time of the lost motion due to the
excessive lost motion is suppressed and the smooth operation cam be
realized.
[0148] Furthermore, the present invention is applicable to the
variably operated valve system of a lift type having no hydraulic
pressure rush adjuster described in a Japanese Patent Application
First Publication (tokkai) No. 2010-270633 published on Dec. 2,
2010. In this case, the valve stop mechanism incorporated in a
valve lifter as shown in a Japanese Patent Application First
Publication (tokkai) No. showa 63-016112 published on Jan. 23, 1988
may be used. Furthermore, the present invention is applicable to a
two-valve stop mechanism. It should be noted that a reference sign
T shown in, for example, FIG. 9 denotes a radial clearance formed
between an inner peripheral surface of cylindrical member 7a of
swing cam 7 and an outer peripheral surface of drive shaft 5.
[0149] Technical ideas graspable from the above-described
embodiments except the claims 1, 2, and 3 will be described
below.
(a) The variably operated valve system for the internal combustion
engine as claimed in claim 1, wherein the valve stop mechanism
includes: a retaining hole that holds one of the pair of fulcrum
members movable; and a basing member that biases the one of the
pair of fulcrum members toward a direction of a corresponding one
of the pair of swing arms and the lost motion is made by moving the
one of the pair of fulcrum members against the biasing member. (b)
The variably operated valve system for the internal combustion
engine as claimed in claim 4, wherein the pair of fulcrum members
are hydraulic pressure rush adjusters. (c) The variably operated
valve system for the internal combustion engine as claimed in claim
1, wherein the valve stop mechanism is disposed only in one of the
pair of fulcrum members and, when the lost motion quantity is equal
to or below the predetermined value, only one of the two engine
valves corresponding to the one of the pair of fulcrum members is
allowed to be stopped through the valve stop mechanism.
[0150] According to the present invention described in item (c),
the one-valve stop is carried out and a swirl effect becomes large
so that the improvement in fuel economy can be achieved.
(d) The variably operated valve system for the internal combustion
engine as claimed in claim 1, wherein the valve stop mechanism is
disposed in both of the pair of fulcrum members and, when the lost
motion quantity is equal to or below the predetermined quantity,
both of the two engine valves are allowed to be stopped through the
valve stop mechanism.
[0151] According to the present invention described in item (d),
both of the engine valves are stopped so that the corresponding
engine cylinder is in the cylinder stopped state, a throttle valve
of each of the remaining others of the engine cylinders which is
not stopped can largely be opened, and a pumping loss can be
reduced.
(e) According to the present invention described in item (c),
wherein, when the valve stop inhibiting means mechanically inhibits
the lost motion of the one of the pair of fulcrum members when the
lost motion quantity exceeds the predetermined value. (f) The
variably operated valve system for the internal combustion engine
as set forth in item (a), wherein the swing fulcrum of each of the
pair of each of the pair of swing arms is formed by a spherical
recess section disposed on a corresponding one of the pair of swing
arms and a spherical convex section engaged with the recess
section. (g) The variably operated valve system for the internal
combustion engine as set forth in item (a), wherein, when the valve
stop inhibiting means mechanically inhibits the lost motion of the
one of the pair of fulcrum members when the lost motion quantity
exceeds the predetermined value. (h) The variably operated valve
system for the internal combustion engine as set forth in item (a),
wherein the control shaft includes a control cam that is in an
eccentricity state to an axial center of the control shaft, the
control cam is inserted through the transmission mechanism, and the
posture of the transmission mechanism is varied according to a
rotation of the control cam. (i) The variably operated valve system
for the internal combustion engine as set forth in item (g),
wherein a limitation of the lost motion is made by a limitation of
a movement of the one of the pair of fulcrum members by means of a
projection section in a movable range of the one of the pair of
fulcrum members. (j) The variably operated valve system for the
internal combustion engine as set forth in item (g), wherein the
valve stop inhibit means is constituted by a movement purpose hole
and a limitation purpose hole, both of the movement purpose and
limitation purpose holes being disposed in the one of the pair of
fulcrum members and in an inner wall of the retaining hole, and a
limitation pin movably disposed across the movement purpose hole
and the limitation purpose hole and a state in which the one of the
pair of fulcrum members is in a locked state by disposing the
limitation pin across the movement purpose hole and the limitation
purpose hole and another state in which the limitation pin is
housed in the movement purpose hole to enable the one of the pair
of fulcrum members to make the lost motion are controlled. (k) The
variably operated valve system for the internal combustion engine
as set forth in item (j), wherein the valve stop inhibiting means
includes another biasing member disposed in the movement purpose
hole of the one of the pair of fulcrum members to bias the
limitation pin toward a direction of the limitation purpose hole
and a hydraulic pressure circuit that supplies a hydraulic pressure
to press under pressure the limitation pin in another direction of
the movement purpose hole of the one of the pair of fulcrum members
against the biasing force of the other biasing member. (l) The
variably operated valve system for the internal combustion engine
as set forth in item (k), wherein the hydraulic pressure circuit
includes: oil passage holes disposed at a bearing section of the
control shaft and a communication hole penetrated through a
diameter direction of the control shaft to appropriately
communicate with the oil passage holes and wherein, when the
control shaft is rotated through an angle equal to or below a
predetermined rotation angle, both of the oil passage holes and the
communication hole are communicated with each other and, when the
control shaft exceeds the predetermined rotation angle, the
communication between the oil passage holes and communication hole
is interrupted. (m) The variably operated valve system for the
internal combustion engine as set forth in item (k), wherein, when
the lost motion quantity is smaller than the predetermined value of
the lost motion quantity of the one of the pair of fulcrum members,
a hydraulic pressure is supplied to move the limitation pin toward
the direction of the movement purpose hole against a biasing force
of the other biasing member and, when the lost motion quantity
exceeds the predetermined value, the biasing force of the other
biasing member causes the limitation pin toward the direction of
the limitation purpose hole. (n) The variably operated valve system
for the internal combustion engine as set forth in item (a),
wherein an angle which is a subtraction of 90.degree. from an angle
formed between the corresponding one of the pair of swing arms and
the one of the pair of fulcrum members when the lost motion
quantity of the fulcrum member is at the predetermined value is
smaller than an angle formed between the corresponding one of the
pair of swing arms and the one of the pair of fulcrum members when
the engine valves are open at a time of a maximum lift control.
[0152] According to the present invention described in item (n), a
degree of worsening of a posture of the corresponding one of the
pair of swing arms becomes more favorable that the worsening of the
posture of the corresponding swing arm at the valve open position
at the time of the maximum lift control so that the valve stop
operation can more smoothly be made.
(o) The variably operated valve system for the internal combustion
engine as set forth in item (a), wherein the valve stop inhibiting
means includes a limitation member that limits the lost motion by
biasing the one of the pair of fulcrum members toward a direction
of the corresponding one of the pair of swing arms, when the lost
motion quantity of the one of the pair of fulcrum members exceeds
the predetermined value. (p) The variably operated valve system for
the internal combustion engine as claimed in claim 14, wherein the
valve stop inhibiting means includes a valve stop inhibit circuit
constituted by a control unit that interrupts the supply of the
hydraulic pressure via an electromagnetic switching valve of the
hydraulic pressure circuit. (q) The variably operated valve system
for the internal combustion engine as set forth in item (p),
wherein the predetermined value of the lost motion quantity can
arbitrarily be set according to a driving condition of the
engine.
[0153] According to the present invention described in item (q),
the inhibited lost motion quantity can arbitrarily be set. Thus,
for example, an effective suppression of the irregular behavior at
the time of the valve stop can be made at the high engine speed
region (area).
[0154] This application is based on a prior Japanese Patent
Application No. 2012-140574 filed in Japan on Jun. 22, 2012. The
entire contents of this Japanese Patent Application No. 2012-140574
are hereby incorporated by reference. Although the invention has
been described above by reference to certain embodiments of the
invention, the invention is not limited to the embodiment described
above. Modifications and variations of the embodiments described
above will occur to those skilled in the art in light of the above
teachings. The scope of the invention is defined with reference to
the following claims.
* * * * *