U.S. patent application number 11/220857 was filed with the patent office on 2007-02-22 for internal combustion engine capable of selectively resting certain cylinders during low-load operation, and method of using same.
This patent application is currently assigned to Honda Motor Co., Ltd.. Invention is credited to Hayato Maehara, Shinji Saito, Takaaki Tsukui.
Application Number | 20070039586 11/220857 |
Document ID | / |
Family ID | 35149635 |
Filed Date | 2007-02-22 |
United States Patent
Application |
20070039586 |
Kind Code |
A1 |
Maehara; Hayato ; et
al. |
February 22, 2007 |
INTERNAL COMBUSTION ENGINE CAPABLE OF SELECTIVELY RESTING CERTAIN
CYLINDERS DURING LOW-LOAD OPERATION, AND METHOD OF USING SAME
Abstract
An internal combustion engine incorporating rest cylinders is
provided which does not need a high response performance when
operating a throttle valve and which can eliminate engine output
variations as the number of operable cylinders changes. In the
internal combustion engine, some of a plurality of cylinders is
configured to rest during normal operation of the engine. The
cylinders are divided into a plurality of cylinder groups, and each
of the cylinders is provided with an independent throttle valve. An
ECU for increasing the number of operative cylinder groups
according to at least the throttle handgrip opening is provided.
Also provided are motors for bringing the throttle valves in the
cylinder in the rest state into a fully closed state on the basis
of each cylinder group, a throttle valve position sensor, and the
like.
Inventors: |
Maehara; Hayato; (Saitama,
JP) ; Saito; Shinji; (Saitama, JP) ; Tsukui;
Takaaki; (Saitama, JP) |
Correspondence
Address: |
CARRIER BLACKMAN AND ASSOCIATES
24101 NOVI ROAD
SUITE 100
NOVI
MI
48375
US
|
Assignee: |
Honda Motor Co., Ltd.
Minato-ku
JP
|
Family ID: |
35149635 |
Appl. No.: |
11/220857 |
Filed: |
September 7, 2005 |
Current U.S.
Class: |
123/198F ;
123/336; 123/90.16 |
Current CPC
Class: |
F02D 41/0087 20130101;
F01L 13/0005 20130101; F02D 9/105 20130101; F02B 61/02 20130101;
F02D 13/06 20130101; F01L 1/143 20130101; F01L 2800/06 20130101;
F02D 13/0257 20130101; Y02T 10/18 20130101; F01L 1/205 20130101;
F02D 9/1095 20130101; F02D 11/105 20130101; F02D 13/0207 20130101;
F02D 17/02 20130101; F02D 13/0203 20130101; F02D 9/02 20130101;
Y02T 10/12 20130101; F02D 41/008 20130101; F02B 2275/16
20130101 |
Class at
Publication: |
123/198.00F ;
123/336; 123/090.16 |
International
Class: |
F02D 17/02 20060101
F02D017/02; F02D 9/10 20060101 F02D009/10; F01L 1/34 20060101
F01L001/34; F02D 13/06 20060101 F02D013/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 7, 2004 |
JP |
2004-259615 |
Claims
1. An internal combustion engine capable of selectively and
temporarily disabling one or more cylinders during low-load
operation thereof, said engine comprising a plurality of cylinders,
at least some of said cylinders configured to be capable of
selectively resting during engine operation, wherein said cylinders
are divided into a plurality of cylinder groups, and each cylinder
is provided with a throttle valve which is capable of being
actuated in response to a throttle operation by a driver, wherein
the engine further comprises a cylinder control unit for selecting
cylinder groups to be operative or inoperative at a given time,
according to at least a throttle operation, and a throttle valve
control mechanism for each of said cylinder groups, which permits
full closure of the throttle valves of the inoperative cylinders,
and wherein each cylinder is provided with four or more valves and
each cylinder comprises at least one valve stop mechanism the valve
stop mechanism capable of transitioning a selected operable
cylinder into a resting state by effecting an all-valve stop
condition in which all of the valves of said selected cylinder are
stopped and wherein a partial valve stop operation can be conducted
by stopping only some of the valves of the selected cylinder.
2. The internal combustion engine of claim 1, wherein said cylinder
control unit is operable to increase a number of operative cylinder
groups when at least some of said cylinder groups are inoperative,
and when the engine speed is at or above a predetermined value.
3. The internal combustion engine of claim 1, wherein a
determination of whether to effect said partial valve stop
operation is made according to engine speed.
4. The internal combustion engine of claim 1, wherein at the time
of the partial valve stop operation, adjacent exhaust valves in two
adjacent cylinders are selected as operative valves, and an exhaust
device is provided between said adjacent exhaust valves.
5. The internal combustion engine of claim 1, wherein four
cylinders are provided, and an initial number of operative
cylinders is two, and the number of operative cylinders is capable
of being subsequently increased one cylinder at a time, based on a
sensed throttle operation amount.
6. The internal combustion engine of claim 1, wherein each cylinder
has four or more valves, and each cylinder comprises at least one
valve stop mechanism, the valve stop mechanism capable of
transitioning a selected operable cylinder into a partially
operable state or a resting state during engine operation, by
temporarily interrupting an open-and-close action of at least one
valve of each cylinder.
7. The internal combustion engine of claim 1, wherein each cylinder
has plural valves, and each cylinder comprises at least one valve
stop mechanism, a valve stop mechanism operatively connected to a
single valve, wherein each valve comprises a valve stem and a valve
lifter, the valve lifter supported by a body of the engine and
comprising a cylinder having a closed upper end and a passage
formed therein and aligned with an axial direction of the valve
stem, an end of the valve stem is received within the passage
formed in the valve lifter, the valve stop mechanism is disposed
within the valve lifter adjacent to the closed upper end, the valve
stop mechanism comprising: a substantially spool-shaped pin holder
having a slide hole formed therein substantially transverse to the
axis direction of the valve stem, a sliding pin disposed within the
slide hole of the pin holder and slidably reciprocally movable
therein in a direction substantially transverse to the axis
direction of the valve stem, the sliding pin having a through
channel formed therethrough and capable of being aligned in
parallel to the axis direction of the valve stem, such that when
the valve stop mechanism is operated to stop valve operation, the
sliding pin is positioned within the valve lifter such that the
passage is aligned with the through channel, permitting the upper
end of the valve stem to be received in both the valve lifter
passage and the through channel of the sliding pin, thereby
preventing the valve lifter from lifting the valve, and when the
valve stop mechanism is operated to temporarily interrupt valve
operation, the sliding pin is positioned within the valve lifter to
a position in which the through channel thereof is out of alignment
with the upper end of the valve stem, and the valve stem resides
only within the valve lifter passage and is prevented from entering
the through channel of the sliding pin, thereby permitting the
valve lifter to lift the valve.
8. A control system for an internal combustion engine of a vehicle,
the vehicle comprising an internal combustion engine actuated by a
throttle actuator, the internal combustion engine comprising a
plurality of cylinders, at least some of the plurality of cylinders
configured to be selectively inoperative during engine operation,
wherein each cylinder is provided with an independent throttle
valve actuated by a throttle operation of a driver, all cylinders
are divided into a plurality of cylinder groups, each cylinder
group provided with a corresponding throttle control mechanism,
each cylinder is provided with four or more valves and each
cylinder comprises at least one valve stop mechanism wherein the
engine further comprises a controller for determining the number of
operative cylinder groups in use during operation of the engine, a
sensor for sensing the amount of operation of the throttle
actuator, wherein the number of operative cylinder groups is
selected according to at least the amount of operation of the
throttle actuator, wherein the controller controls each valve stop
mechanism according to engine speed in order to permit
transitioning of a selected operable cylinder into either a resting
state by effecting an all-valve stop condition in which all of the
valves of said selected cylinder are stopped or a partial valve
stop state by stopping only some of the valves of the selected
cylinder.
9. The control system for an internal combustion engine of claim 8,
wherein the engine further comprises a sensor for sensing the
engine speed, and wherein the number of operative cylinder groups
is selected by the controller according to the amount of operation
of the throttle actuator and based on whether the engine speed is
higher than a predetermined threshold value.
10. The control system for an internal combustion engine of claim
9, wherein the cylinder groups comprise a first cylinder group
comprising two cylinders, a second cylinder group comprising one
cylinder, and a third cylinder group comprising one cylinder,
wherein when the engine speed is lower than the predetermined
threshold, and the amount of operation of the throttle actuator is
in the range of zero to a first predetermined value, the number of
operative cylinder groups is selected by the controller to be one,
the one selected operative cylinder group comprising the first
cylinder group operated using a partial valve stop operation.
11. The control system for an internal combustion engine of claim
10, wherein when the engine speed is lower than the predetermined
threshold, and the amount of operation of the throttle actuator is
in the range between the first predetermined value and a second
predetermined value, the number of operative cylinder groups is
selected by the controller to be two, the two selected operative
cylinder groups comprising the first cylinder group and the second
cylinder group, both groups operated using a partial valve stop
operation.
12. The control system for an internal combustion engine of claim
11, wherein when the engine speed is lower than the predetermined
threshold, and the amount of operation of the throttle actuator is
in the range between the second predetermined value and a third
predetermined value, the number of operative cylinder groups is
selected by the controller to be three, the three selected
operative cylinder groups comprising a partial valve stop
operation.
13. The control system for an internal combustion engine of claim
12, wherein when the engine speed is at least the predetermined
threshold, the number of operative cylinder groups is selected by
the controller to be three, the three selected operative cylinder
groups comprising no valve stop operation.
14. An method of selectively and temporarily disabling one or more
cylinders of an internal combustion engine during low-load
operation thereof, said engine comprising a plurality of cylinders,
wherein said cylinders are divided into a plurality of cylinder
groups; each of said cylinders is provided with at least one intake
valve and at least one exhaust valve; each cylinder is provided
with an associated throttle valve which is capable of being
actuated in response to a throttle operation by a driver, and each
cylinder is provided with at least four valves and wherein each
cylinder comprises at least one valve stop mechanism the valve stop
mechanism capable of transitioning a selected operable cylinder
into a resting state by effecting an all-valve stop condition in
which all of the valves of said selected cylinder group are stopped
and wherein a partial valve stop operation can be conducted by
stopping only some of the valves of the selected cylinder, said
method comprising the steps of: sensing an instantaneous throttle
actuation level requested by a driver at a given time; operating
the throttle valve of at least one of said cylinder groups in
proportion to said sensed throttle actuation level; inactivating a
throttle valve associated with at least one selected cylinder group
of said cylinder groups, and temporarily interrupting operation of
the intake and exhaust valves of said selected cylinder group via
corresponding valve stop mechanisms when said sensed throttle
actuation level is below a predetermined threshold; and
reactivating the throttle valve associated with the selected
cylinder group and resuming operation of the intake and exhaust
valves of said selected cylinder group when the sensed throttle
actuation level exceeds the predetermined threshold.
15. The method of claim 14, further comprising a step of increasing
a number of operative cylinder groups with a cylinder control unit
when at least some of said cylinder groups are inoperative, when
the sensed throttle actuation level exceeds the predetermined
threshold and when the engine speed is at or above a predetermined
value.
16. The method of claim 14, wherein a determination of whether to
effect said partial valve stop operation is made according to
engine speed.
17. The method of claim 14, wherein at the time of the partial
valve stop operation, adjacent exhaust valves in two adjacent
cylinders are selected as operative valves, and an exhaust device
is provided between said adjacent exhaust valves.
18. The method of claim 14, wherein four cylinders are provided,
wherein an initial number of operative cylinders is two, and
wherein the number of operative cylinders is subsequently increased
one cylinder at a time, based on the sensed throttle actuation
level.
19. The method of claim 14, wherein each cylinder has plural
valves, and each cylinder comprises at least one valve stop
mechanism, a valve stop mechanism operatively connected to a single
valve, wherein each valve comprises a valve stem and a valve
lifter, the valve lifter supported by a body of the engine and
comprising a cylinder having a closed upper end and a passage
formed therein and aligned with an axial direction of the valve
stem, an end of the valve stem is received within the passage
formed in the valve lifter, the valve stop mechanism is disposed
within the valve lifter adjacent to the closed upper end, the valve
stop mechanism comprising: a substantially spool-shaped pin holder
having a slide hole formed therein substantially transverse to the
axis direction of the valve stem, a sliding pin disposed within the
slide hole of the pin holder and slidably reciprocally movable
therein in a direction substantially transverse to the axis
direction of the valve stem, the sliding pin having a through
channel formed therethrough and capable of being aligned in
parallel to the axis direction of the valve stem, such that when
the valve stop mechanism is operated to stop valve operation, the
sliding pin is positioned within the valve lifter such that the
passage is aligned with the through channel, permitting the upper
end of the valve stem to be received in both the valve lifter
passage and the through channel of the sliding pin, thereby
preventing the valve lifter from lifting the valve, and when the
valve stop mechanism is operated to temporarily interrupt valve
operation, the sliding pin is positioned within the valve lifter to
a position in which the through channel thereof is out of alignment
with the upper end of the valve stem, and the valve stem resides
only within the valve lifter passage and is prevented from entering
the through channel of the sliding pin, thereby permitting the
valve lifter to lift the valve.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present invention claims priority under 35 USC 119 based
on Japanese patent application No. 2004-259615, filed on Sep. 7,
2004. The subject matter of this priority document is incorporated
by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a multi-cylinder internal
combustion engine, in which at least some of a plurality of
cylinders are capable of selectively resting during engine
operation under low load.
[0004] 2. Description of the Background Art
[0005] Among multiple-cylinder internal combustion engines, an
engine is known in which some of the cylinders selectively rest, or
become non-operative, during normal engine operation under certain
low-load conditions. With some of the cylinders being permitted to
rest during normal engine operation, it is possible to obtain an
improvement in fuel consumption at the time of a low-load operation
or the like, and also to produce extra power when needed, by
operating all the cylinders at the time of a high-load operation.
Specifically, there is a known system in which an engine control is
performed that permits an increase the number of operating
cylinders from two cylinders to three cylinders and, further, to
four cylinders attendant on the transition from a low-load
operation to a high-load operation. Such an engine is disclosed,
for example, in Japanese Laid-open Patent publication No. Hei
08-105337.
[0006] In Japanese Laid-open Patent publication No. Hei 08-105337,
an ignition-retarding operation is carried out, for suppressing a
forward surge, arising from an increase in engine torque, which
would otherwise be experienced at the time of changeover at a time
when a cylinder transitions from a resting mode to an operating
mode. It has become apparent, however, that control of the intake
air quantity is effective for obtaining a further suppression of
output variation during transitional periods. However, in the case
of controlling the intake air quantity by using a single throttle
valve, a high response performance is required for driving the
throttle valve, at the time of changing over the number of
cylinders. As a result, manufacturing costs are increased in order
to realize the high performance response. In addition, in order to
control the intake quantities for a plurality of cylinders by use
of a single throttle valve, a complicated control system is
needed.
[0007] In view of the foregoing, it is an object of the present
invention to provide an internal combustion engine which is capable
of selectively resting some of the engine cylinders, which does not
need a high performance response in operating throttle valves, and
which can eliminate a step change in engine output at the time of
changing the number of operating cylinders.
SUMMARY OF THE INVENTION
[0008] In order to attain the above object, a first aspect of the
invention resides in an internal combustion engine incorporating a
cylinder rest procedure in which one or more of a plurality of
cylinders are selectively permitted to rest, or become
non-operative, during operation of the engine. The invention is
characterized in that all the cylinders are divided into a
plurality of cylinder groups, and each of the cylinders is provided
with an independent throttle valve (for example, the throttle valve
TH in the illustrative embodiment described herein). In addition, a
cylinder number control unit (for example, the ECU 70 in the
illustrative embodiment described herein) for selectively
increasing the number of the operative cylinder groups according to
at least a throttle operation variable (for example, the handgrip
opening .theta.g in the illustrative embodiment described herein)
is provided. A throttle valve control mechanism (for example, the
motors 21A, 21B, the throttle valve position sensor 22, etc. in the
illustrative embodiment described herein) actuates the throttle
valve(s) of the resting cylinder(s) for movement between a fully
open and closed position, and is provided for each cylinder
group.
[0009] With such a configuration, by using the independent throttle
valves, an independent throttle valve control is performed on the
basis of each cylinder group. In addition, the need for performing
an engine output surge suppressing control, by use of other
controlled variable(s), is eliminated.
[0010] A second aspect of the invention is characterized in that
the cylinder number control unit increases the number of the
operative cylinder groups when the engine speed is not less than a
predetermined value (for example, the threshold value a in the
illustrative embodiment described herein) when at least some of the
cylinder groups are in the resting state.
[0011] With such a configuration, the number of operating cylinders
can be varied, not only according to the throttle opening, but also
according to the engine speed.
[0012] A third aspect of the invention is characterized in that
each cylinder has four or more valves (for example, the intake
valves 461, 462, and exhaust valves 471, 472 in the illustrative
embodiment described herein). A valve stop mechanism (for example,
the valve stop mechanism 63 and the valve stop mechanism 69 in the
illustrative embodiment described herein) is provided for at least
some of the valves of the cylinder. The valve stop mechanism
produces a cylinder resting state by effecting an all valve resting
condition, where all the valves of the cylinder are resting. In
addition, a partial valve stop, or rest, operation can be conducted
by bringing some of the valves of each cylinder into a resting
state according to the engine speed.
[0013] With such a configuration, a temporary interruption of
cylinder operation can be realized by operating the valve stop
mechanism on all valves of a cylinder. In addition, it is possible
to change the number of valves stopped on a given cylinder,
according to the engine speed.
[0014] A fourth aspect of the invention is characterized in that at
the time of a partial valve rest, adjacent exhaust valves (for
example, the exhaust valves 471 and 472 in the illustrative
embodiment described herein) in two adjacent cylinders are selected
as operative valves, and an exhaust device (for example, a
secondary air introduction valve A1 in the illustrative embodiment
described herein) is provided between said adjacent exhaust
valves.
[0015] A fifth aspect of the invention is characterized in that in
a four cylinder engine, during engine operation the number of
operating cylinders is increased from two cylinders, to three
cylinders, and then to four cylinders, attendant on an increase in
throttle operation by the vehicle operator.
[0016] With such a configuration, it is possible to increase the
number of operating cylinders by adding the operation of one
cylinder at a time, and thereby to operate in a region in which the
load factor of each cylinder is high.
[0017] According to the first aspect of the invention, an
independent throttle valve control can be performed on the basis of
each cylinder group by use of independent throttle valves, so that
the need for a high response performance in driving the throttle
valves is eliminated. Additionally, engine output variations,
especially step increases in engine output at the time of changing
over the number of operative cylinders, can be suppressed. In
addition, the need to perform an output variation suppressing
control by other controlled variable(s) is eliminated, and the
control is simplified.
[0018] Further, since the number of cylinders is varied based on at
least a throttle operation variable, the fuel consumption can be
improved while achieving an output demanded by the driver, by
reading the driver's intention from the controlled variable.
[0019] According to the second aspect of the invention, the number
of cylinders can be varied according to not only the throttle
operation but also the engine speed, so that the load factor of
each cylinder can be enhanced appropriately, and compatibility
between engine output and fuel consumption can be achieved.
[0020] In addition, the number of operative cylinders is large in
the region where the throttle operation variable is low and the
engine speed is high, i.e., at the time of engine brake or the
like, so that an appropriate engine brake can be secured.
[0021] According to the third aspect of the invention, cylinder
stop, or rest, can be realized by effecting valve stop for all
valves of a cylinder, so that the oil pumping loss can be reduced,
and an improvement in fuel consumption can be obtained. In
addition, since the number of valves can be changed between rest
and operational according to the engine speed, the engine output
can be made appropriate to the requirements of the operator.
Additionally, since each cylinder group is provided with the
throttle valve control mechanism, engine output variations at the
time of changing over the valves can be suppressed.
[0022] According to the fourth aspect of the invention, intake air
can be introduced into the cylinder by resting the intake valve on
one side of the cylinder, so that an air swirl flow pattern can be
generated within the cylinder, resulting in an improvement in fuel
consumption. In addition, the layout position of the exhaust device
can be made compact.
[0023] According to the fifth aspect of the invention, it is
possible to increase the number of cylinders from two cylinders by
one cylinder at a time, and to operate in the region where the load
factor of each cylinder is high, so that an improvement in fuel
consumption is obtained.
[0024] Modes for carrying out the present invention are explained
below by reference to an embodiment of the present invention shown
in the attached drawings. The above-mentioned object, other
objects, characteristics and advantages of the present invention
will become apparent form the detailed description of the
embodiment of the invention presented below in conjunction with the
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a top plan view of a major part of a four cylinder
engine of one embodiment of the present invention, showing a cam
chain case disposed at one end of the cylinder block, and oil
pressure control valves disposed at the opposed end of the cylinder
block.
[0026] FIG. 2 is a sectional view of the engine along line 2-2 of
FIG. 1 showing the number four cylinder of the engine in which a
first exhaust valve includes a valve stop mechanism, and a second
intake valve is formed conventionally.
[0027] FIG. 3 is a sectional view of the engine along line 3-3 of
FIG. 1 showing the number four cylinder of the engine in which a
second exhaust valve is formed conventionally, and a first intake
valve includes a valve stop mechanism.
[0028] FIG. 4 is a sectional view of the engine along line 4-4 of
FIG. 1 showing the throttle body configuration in which the number
three and four cylinders form a cylinder group and share a throttle
valve control mechanism, the number two cylinder forms a cylinder
group and has a throttle valve control mechanism, and the number
one cylinder forms a cylinder group and has a throttle valve
control mechanism.
[0029] FIG. 5 is a partially enlarged detail sectional view of a
portion of FIG. 3, showing the valve stop mechanism provided within
the valve lifter of the first intake valve of the fourth cylinder
of the engine.
[0030] FIG. 6 is an isolated top perspective view of the pin holder
of the valve stop mechanism, showing the slide pin within the slide
hole formed in the bridging portion.
[0031] FIG. 7 is an isolated bottom perspective view of the pin
holder of the valve stop mechanism, showing an axially aligned
insertion hole surrounded by a pair of projections used to position
an end portion of a biasing spring.
[0032] FIG. 8 is a perspective view of a slide pin, showing a slit
formed in one end, a flat abutment surface formed along a bottom
surface thereof, and a containing hole extending transversely
through the pin and opening at one side of the abutment
surface.
[0033] FIG. 9 is a system diagram showing a valve operating
condition.
[0034] FIG. 10 is a flow chart showing the process of transitioning
from valve operation to valve rest.
[0035] FIG. 11 is a system diagram showing a valve rest
condition.
[0036] FIG. 12 is a flow chart showing the process of transitioning
from valve rest to valve operation.
[0037] FIG. 13 is a graph diagram showing the relationships of
throttle valve opening and engine speed with respect to handgrip
opening.
[0038] FIG. 14 is an illustration of the valve condition for the
valves of each of the four cylinders where the handgrip opening is
in the range of 0 to .theta.g2.
[0039] FIG. 15 is an illustration of the valve condition for the
valves of each of the four cylinders where the handgrip opening is
in the range of .theta.g2 to .theta.g1.
[0040] FIG. 16 is an illustration of the valve condition for the
valves of each of the four cylinders where the handgrip opening is
not less than .theta.g2.
[0041] FIG. 17 is an illustration of the valve condition for the
valves of each of the four cylinders in 4-valve operation.
DETAILED DESCRIPTION
[0042] A selected illustrative embodiment of the invention will now
be described in some detail, with reference to the drawings. It
should be understood that only structures considered necessary for
clarifying the present invention are described herein. Other
conventional structures, and those of ancillary and auxiliary
components of the system, are assumed to be known and understood by
those skilled in the art. As shown in FIGS. 1 to 3, an engine E,
according to the selected illustrative embodiment hereof, is a
water-cooled, 4-cylinder motorcycle engine, for example. In the
engine E, a cylinder head 40 is fixed on the top face of a cylinder
block 30, and a head cover 41 is mounted to the top face of the
cylinder head 40.
[0043] A cam chain case C is formed at a side portion of the engine
E. A number one (#1) cylinder, a number two (#2) cylinder, a number
three (#3) cylinder and a number four (#4) cylinder are arranged
along the vehicle width direction, starting from the side of the
engine opposite the cam chain case C. Each of these cylinders is
provided with four valves, including two intake valves and two
exhaust valves, which will be described later.
[0044] As shown in FIGS. 2 and 3, a throttle body 20 is connected
to the cylinder head 40 so as to be oriented substantially
horizontally. An intake air duct 16 is connected to the throttle
body 20 on the upstream side thereof. During engine operation,
intake air passes through an intake passage 17 formed in the
throttle body, and is subsequently introduced to each cylinder via
an intake port 18 formed in the cylinder head 40.
[0045] A butterfly-type throttle valve TH is provided in the intake
passage 17 of the throttle body 20. The throttle valve TH is
adjustably movable through a range extending between a fully opened
position and a fully closed position. The throttle valve TH is
operated by a so-called drive-by-wire or electronic throttle
control system, in which the throttle valve TH is opened and closed
in conjunction with a motor 21 according to an angular handgrip
opening (throttle operation variable) .theta.g, i.e., the amount of
operation of the throttle handgrip by the driver, indicating the
driver's intention toward acceleration or the like. In addition, a
throttle valve position sensor (throttle valve control mechanism)
22 for detecting the throttle valve opening is connected to the
throttle valve TH, so that the accurate turn angle of the throttle
valve TH turned by the motor 21 can be detected.
[0046] As shown in FIG. 4, in the throttle body 20, a throttle body
block (throttle valve control mechanism) 200 is provided with four
throttle valves TH, TH, TH, TH, wherein a throttle valve TH is
provided for each cylinder. The throttle body block 200 is composed
by interconnecting a third-fourth throttle body block (throttle
valve control mechanism) 200A corresponding to the #4 cylinder and
the #3 cylinder, a second throttle body block (throttle valve
control mechanism) 200B corresponding to the #2 cylinder, and a
first throttle body block (throttle valve control mechanism) 200C
corresponding to the #1 cylinder.
[0047] Therefore, the #3 cylinder and the #4 cylinder,
corresponding to the third-fourth throttle body block 200A,
constitute a first cylinder group, the #2 cylinder corresponding to
the second throttle body block 200B constitutes a second cylinder
group, though it is a single cylinder, and the #1 cylinder
corresponding to the first throttle body block 200C constitutes a
third cylinder group, though it is a single cylinder. Thus, the
engine E according to the illustrative embodiment includes three
cylinder groups.
[0048] A third-fourth shaft 23 is a throttle valve shaft joining
the respective throttle valves TH of the #3 cylinder and the #4
cylinder, for simultaneous concurrent operation of these throttle
valves. At an end portion of the third-fourth shaft 23 on the side
of the cam chain case C, the throttle valve position sensor 22 is
coaxially mounted to the third-fourth throttle body block 200A by
small screws 24. In addition, a pulley 25 is mounted to an end
portion of the third-fourth shaft 23, on the side thereof opposite
to the cam chain case C. On the other hand, an injector 26, for
injecting fuel into each intake passage (see FIG. 2), is inserted
and fixed to an upper portion, or an upper wall, of the
third-fourth throttle body block 200A, for each of the third and
fourth throttle valves TH, and the injector is inclined with its
lower end aimed toward the cylinder head 40, as shown.
[0049] The injector 26 is connected to a fuel supply line 27 (see
FIG. 1). In addition, a third-fourth motor (throttle valve control
mechanism) 21A is mounted, by a fastening means 29, to the
third-fourth throttle body block 200A, on the side of the main body
block 200A opposite the injector 26. The drive shaft 28 of the
third-fourth motor is parallel to the third-fourth shaft 23. Here,
a pulley 31 is mounted to an end portion of the drive shaft 28, on
the side of the third-fourth motor 21A opposite to the cam chain
case C.
[0050] A pulley 32 for opening and closing the throttle valve TH of
the second throttle body block 200B is mounted to an end portion of
a throttle shaft 35 on the side of the throttle valve TH opposite
to the cam chain case C. The throttle valve position sensor 22 for
sensing the throttle opening of the #2 cylinder is mounted to a
lower portion of the second throttle body block 200B. A pulley 33
is mounted to an end portion of a sensor shaft 34, on the side of
the throttle valve position sensor 22 opposite to the cam chain
case C.
[0051] Additionally, as shown in FIG. 4, a first auxiliary motor
(throttle valve control mechanism) 21B is mounted to the front side
of the throttle valve position sensor 22 and on the side of the
throttle body TH opposite to the injector 26, through a bracket
(not shown). The drive shaft of the first auxiliary motor is
parallel to the shaft 35 of the associated throttle valve TH. A
pulley 36 is mounted to an end portion of the drive shaft of the
first auxiliary motor 21B, on the side thereof opposite to the cam
chain case C.
[0052] In addition, a pulley groove 32M of the pulley 32 and a
pulley groove of the pulley 36 of the motor 21B are connected by an
endless wire loop 37, while a pulley groove 32 of the pulley 32 of
the shaft 35 and a pulley groove of the pulley 33 of the throttle
valve position sensor 22 are connected by an endless wire loop
38.
[0053] Similarly, pulleys 32, 33, 36 are mounted to an end portion
of the first throttle body block 200C corresponding to the #1
cylinder. The pulleys 32, 33, 36 are mounted on a side of the
throttle body TH opposite to the cam chain case C. The throttle
valve position sensor 22 and the motor 21B in a font-rear
relationship are mounted to a lower portion of the first throttle
body block 200C. The pulley 32 and the pulley 36 of the motor 21B
are connected by an endless wire loop 37, while the pulley 32 and
the pulley 33 of the throttle valve position sensor 22 are
connected by an endless wire loop 38.
[0054] As shown in FIGS. 2 and 3, the cylinder head 40 is provided
with a recessed portion 43 for defining a combustion chamber 42
together with the cylinder block 30 and a piston 39. The recessed
portion 43 is provided with intake valve ports 441, 442 and exhaust
valve ports 451, 452. The first intake valve port 441 is opened and
closed by a first intake valve 461, and the second intake valve
port 442 is opened and closed by a second intake valve 462.
Similarly, the first exhaust valve port 451 is opened closed by a
first exhaust valve 471, and the second exhaust valve port 452 is
opened and closed by a second exhaust valve 472. Incidentally, in
the #4 cylinder as shown in FIGS. 2 and 3, the first intake valve
461 is a rest-able (ie, configured to be controlled between a rest
mode and an operating mode) intake valve, and the first exhaust
valve 471 is a rest-able exhaust valve.
[0055] The first and second intake valves 461, 462 have a
configuration in which the lower end of a valve stem 49 is
integrally connected to a valve body portion 48, capable of closing
the corresponding intake valve port 441, 442. The first and second
exhaust valves 471, 472 have a configuration in which the lower end
of a valve stem 51 is integrally connected to a valve body portion
50 capable of closing the corresponding exhaust valve port 451,
452.
[0056] The valve stems 49 of the first and second intake valves 461
and 462 are slidably fitted in valve guide cylinders 52 provided in
the cylinder head 40. Similarly, the valve stems 51 of the first
and second exhaust valves 471 and 472 are slidably fitted in valve
guide cylinders 53 provided in the cylinder head 40.
[0057] A retainer 54 is fixed to a portion of the valve stem 49 of
the first intake valve 461 which projects upward from the valve
guide cylinder 52. The first intake valve 461 is biased, in the
direction of closing the first intake valve port 441, by a coil
form valve spring 551, provided between the retainer 54 and the
cylinder head 40. Similarly, a retainer 54 is fixed to a portion of
the valve stem 49 of the second intake valve 462 which projects
upwards from the valve guide cylinder 52. The second intake valve
462 is biased, in the direction of closing the second intake valve
port 442, by a coil form valve spring 552, provided between the
retainer 54 and the cylinder head 40.
[0058] In the same manner as above, the first exhaust valve 471 is
biased, in the direction of closing the first exhaust valve port
451, by a coil form valve spring 571, provided between a retainer
56 fixed to the valve stem 51 of the first exhaust valve 471 and
the cylinder head 40. The second exhaust valve 472 is biased, in
the direction of closing the second exhaust valve port 452, by a
coil form valve spring 572, provided between a retainer 56 fixed to
the valve stem 51 of the second exhaust valve 472 and the cylinder
head 40.
[0059] The first and second intake valves 461, 462 of the
combustion chambers 42 are driven by an intake-side valve operating
device 58. The intake-side valve operating device 58 includes a
camshaft 60 provided with first intake-side valve operating cams
591, corresponding respectively to the first intake valves 461, and
second intake-side valve operating cams 592 corresponding
respectively to the second intake valves 462. The intake-side valve
operating device 58 also includes bottomed cylindrical valve
lifters 611, slidingly driven by the first intake-side valve
operating cams 591, and bottomed cylindrical valve lifters 612,
slidingly driven by the second intake-side valve operating cams
592.
[0060] The camshaft 60 has an axis orthogonal to extensions of the
axes of the valve stems 49 in the first and second intake valves
461, 462, and is rotatably supported between the cylinder head 40
and the head cover 41 joined to the cylinder head 40. The valve
lifters 611 are slidably fitted in the cylinder head 40 in a
direction coaxial with the axes of the valve stems 49 in the first
intake valves 461, and the closing end outside surfaces of the
valve lifters 611 are in sliding contact with the first intake-side
valve operating cams 591. Similarly, the valve lifter 612 is
slidably fitted in the cylinder head 40 in a direction coaxial with
the axes of the valve stems 49 in the second intake valves 462, and
the closing end outside surfaces of the valve lifters 612 are in
sliding contact with the second intake-side valve operating cams
592.
[0061] Moreover, as shown in FIG. 2, the stem ends of the valve
stems 49 in the second intake valve 462 are brought into contact
with the closing end inside surface of the valve lifter 612 through
a shim 62, and are normally opened and closed by the second
intake-side valve operating cams 592 during the operation of the
engine E.
[0062] On the other hand, as shown in FIG. 3, a valve stop
mechanism 63 is provided between the valve stem 49 of the first
intake valve 461 and the valve lifter 611. The valve stop mechanism
effects a change between action and inaction of the pressing force
from the valve lifter 611 to the first intake valve 461 in the
valve-opening direction, and also brings the first intake valve 461
into the rest state, notwithstanding the sliding operation of the
valve lifter 611, by bringing the pressing force into an inactive
state in a specified operation range, for example, a low load range
such as a low speed operation range of the engine E.
[0063] As shown in FIG. 5, which shows a detail view of a part of
FIG. 3, the valve stop mechanism 63 includes a substantially
spool-shaped pin holder 74 which is slidably fitted in the valve
lifter 611, and the pin holder has a hollow cylindrical bore formed
substantially horizontally therein and defining a slide hole 80 for
receiving a slide pin 76. The valve stop mechanism 63 also includes
the slide pin 76, which is slidably fitted in the slide hole 80 of
the pin holder 74. The slide pin 76, the pin holder 74 and the
valve lifter 611 cooperate to form an oil pressure chamber 75 at an
end portion of the slide hole 80, between an end of the slide pin
and the inside surface of the valve lifter 611. The valve stop
mechanism 63 also includes a return spring 77, which fits inside of
a cylindrical spring chamber 86 formed in an open end portion of
the slide pin 76, and is disposed between the slide pin 76 and the
pin holder 74. The return spring 77 provides a spring force for
biasing the slide pin 76 towards the right in FIG. 5, which is in a
direction of reducing the volume of the oil pressure chamber 75.
The valve stop mechanism 63 further includes a stopper pin 78,
disposed in a substantially vertical orientation between the pin
holder 74 and the slide pin 76, while inhibiting the slide pin 76
from rotating about the axis thereof. In addition, a rest
discrimination sensor 71 is mounted on the side of the cylinder
head 40, for detecting the position of the slide pin 76.
[0064] As shown in FIGS. 6 and 7, the spool-shaped pin holder 74
has a cylindrical ring portion 74a extending around an outer
circumference thereof, for slidably fitting in the valve lifter 611
(see FIG. 5). The ring portion 74a is provided with outwardly
extending flanges 55a, 55b extending outwardly thereon at both its
top and bottom edges, as shown. An annular groove 79 is defined in
the outer circumference of the ring portion 74a between the upper
and lower flanges 55a, 55b of the ring portion 74a. In addition, a
bridging portion 74b extends between and connects inner
circumferential portions of the ring portion 74a, and is integrally
formed along a diameter of the ring portion 74a (The slide hole 80
is formed inside of the bridging portion 74b). Portions of the pin
holder 74 are lightened, that is partially removed, between the
inner circumference of the ring portion 74a and both side surfaces
of the bridging portion 74b, in order to obtain a reduction in
weight. Such a pin holder 74 may be formed by lost wax casting, by
forging of iron or an aluminum alloy, or may be formed from a
high-strength synthetic resin. A cementation treatment is applied
to the outer circumferential surface of the pin holder 74, i.e.,
the outer circumferential surface of the ring portion 74a, which is
made of a metal, and to the inner circumferential surface of the
valve lifter 611, thereby integrally affixing the pin holder 74 to
the interior surface of the valve lifter 611.
[0065] The bridging portion 74b is provided with the slide hole 80
formed therein, as noted, and the slide hole 80 has an axis
extending in the longitudinal direction of the bridging portion
74b, i.e., in a direction orthogonal to the axis of the valve
lifter 611. The slide hole 80 has a dead-headed or bottomed shape,
with one end being opened to the annular groove 79, and the other
end being closed. In addition, the bridging portion 74b is provided
with an insertion hole 81 formed in a central lower portion thereof
(FIG. 7), which communicates with the slide hole 80. The bridging
portion 74b is also provided with an extension hole 82 formed in a
central upper portion thereof (FIG. 6), which also communicates
with the slide hole 80, and which is coaxial with the insertion
hole 81. The bridging portion 74b is integrally provided with a
hollow cylindrical seat 83 formed therein at an upper central
portion thereof in the periphery of the extension hole 82,
extending coaxially with the axis of the extension hole 82.
Further, the bridging portion 74b is provided with a upper pin
mount hole 90 which communicates with the slide hole 80. The upper
pin mount hole 90 is formed in an upper section of the bridging
portion 74b at one side of the seat 83, and positioned in the
region extending from a portion corresponding to the one end (open
end) of the slide hole 80 to the extension hole 82. Similarly, as
shown in FIG. 5, the bridging portion 74b is provided in its lower
portion with a lower pin mount hole 89 which communicates with the
slide hole 80, positioned in a region of the bridge portion
extending from a portion corresponding to the one end (open end) of
the slide hole 80 to the insertion hole 81. The lower pin mount
hole 89 is aligned with and formed coaxially with the upper pin
mount hole 90, and the stopper pin 78 is mounted therein.
[0066] A solid, disk-like shim 84 (FIG. 5) is fitted in the seat 83
of the pin holder 74, and an end portion of the extension hole 82
is thereby closed. A central dependent boss 85 of the valve lifter
611, provided at a central portion of the inside surface of the
closed end of the valve lifter 611, rests on and abuts on the shim
84. A stem end 49a of the valve stem 49 of the first intake valve
461 is inserted in the insertion hole 81 in the lower portion of
the pin holder 74. In addition, the slide pin 76 is slidably fitted
in the slide hole 80. The oil pressure chamber 75 communicates with
the annular groove 79, and is formed between one end of the slide
pin 76 and the inside surface of the valve lifter 611. The return
spring 77 is contained in a spring chamber 86 formed between the
other end of the slide pin 76 and the closed end of the slide hole
80. In cases where the pin holder 74 is made of a synthetic resin,
its portion for sliding contact with the slide pin 76 may be
provided as a metal insert, which fits into the body of the
synthetic pin holder.
[0067] As shown in FIGS. 5 and 8, the slide pin 76 is provided with
a containing hole 87 formed through in an intermediate portion of
the slide pin, in the axial direction thereof. The containing hole
87 coaxially communicates with the insertion hole 81 and the
extension hole 82, and has such a diameter that the stem end 49a of
the valve stem 49 can be contained therein. Further, an end portion
of the containing hole 87, on the side of the insertion hole 81, is
opened to a flat abutment surface 88 formed on the outside surface
of a lower portion of the slide pin 76, oppositely to the insertion
hole 81. Here, the abutment surface 88 is formed to be
comparatively long along the axial direction of the slide pin 76,
and the containing hole 87 is opened to a portion of the abutment
surface 88, on the side of the spring chamber 86. In addition, as
seen best in FIG. 8, a slit 91 is provided on one end side of the
slide pin 76, opened toward the side of the oil pressure chamber
75,. A magnetism-generating member, such as a magnet, is embedded
in the slide pin 76 so as to enhance the detection accuracy of a
rest discriminating magnetic sensor 71, which will be described
later.
[0068] Additionally, the slide pin 76 is provided with an axial
communication hole 96, extending axially therein between the spring
chamber 86 and the containing hole 87, for permitting fluid
communication therebetween. The axial communication hole 96
prevents variations from occurring in the pressure inside the
spring chamber 86, when the slide pin 76 is moved in the axial
direction. Further, as shown in FIGS. 5 and 6, the pin holder 74 is
provided with an upper communication hole 97, on the opposite side
of the bridge from the upper mounting hole 90, for permitting
communication between the spring chamber 86 and the space inside of
the valve lifter 611 above the pin holder 74. The upper
communication hole 97 prevents the pressure in the space from
varying with temperature. In addition, a wall portion 79a of the
annular groove 79 forming the spring chamber 86 is provided with an
opening 79b. The diameter of the opening 79b is set smaller than
the diameter of the return spring 77.
[0069] Further, a coil spring 92 is provided between the pin holder
74 and the cylinder head 40, for biasing the pin holder 74 in the
direction of abutting the shim 84 mounted to the pin holder 74
against the central dependent boss 85 of the valve lifter 611. The
coil spring 92 is mounted so as to surround the valve stem 49 at
such a position as to obviate the contact of its outer
circumference with the inside surface of the valve lifter 611. The
lower surface of the bridging portion 74b of the pin holder 74 is
integrally provided with a pair of projections 93, 94 (FIGS. 5, 7)
for positioning an end portion of the coil spring 92 in a direction
orthogonal to the axis of the valve stem 49.
[0070] Both the projections 93, 94 are projectingly provided
integrally on the pin holder 74 with a projection amount not more
than the wire diameter of the coil spring 92, and are formed in a
circular arc shape, with the axis of the valve stem 49 as a center
of the circle. In addition, one projection 93 is provided with a
step portion 95. Step portion 95 abuts an end portion of the
stopper pin 78, on the side of the first intake valve 461, to limit
downward travel of the stopper pin, and to thereby inhibit the
stopper pin 78 from moving toward the side of the first intake
valve 461.
[0071] As illustrated in FIG. 5, the cylinder head 40 is provided
with a support hole 98 for fitting the valve lifter 611 therein so
as to slidably support the valve lifter 611. The support hole 98 is
provided in its inside surface with an annular recessed portion 99
for surrounding the valve lifter 611. The annular recessed portion
99 is connected to a working oil pressure supply passage 103 formed
in the cylinder head 40, and is supplied with a working oil.
Additionally, the valve lifter 611 is provided with a release hole
101 and a lateral communication hole 100 for communicating the
annular recessed portion 99 with the annular groove 79 in the pin
holder 74.
[0072] The lateral communication hole 100 is provided at such a
position as to permit fluid communication between the annular
recessed portion 99 of the cylinder head support hole 98 and the
annular groove 79 of the pin holder 74, notwithstanding the sliding
of the valve lifter 611 in the support hole 98. The release hole
101 is provided in the valve lifter 611 at such a position that the
annular recessed portion 99 communicates with the inside of the
valve lifter 611 on the lower side of the pin holder 74, when the
valve lifter 611 is moved to an uppermost position as shown in FIG.
5, and that the communication with the annular recessed portion 99
is interrupted as the valve lifter 611 is moved downwards from the
uppermost position as shown in FIG. 5, and the working oil is
jetted through the release hole 101 into the inside of the valve
lifter 611 as a lubricating oil.
[0073] The working oil supplied from the working oil pressure
supply passage 103 into the annular groove 79 of the pin holder 74
through the lateral communication hole 100 and the release hole 101
is supplied into the oil pressure chamber 75 of the slide pin, via
one end of the slide hole 80. The slide pin 76 is slid in the axial
direction in such a manner that an oil pressure force, acting on
one end side of the slide pin 76 due to the oil pressure inside the
oil pressure chamber 75, and a spring force acting on the other end
side of the slide pin 76 due to the return spring 77 balance each
other. At a non-operation time (valve rest time), when the oil
pressure in the oil pressure chamber 75 is low, the slide pin 76 is
oriented as shown in FIG. 5, and the stem end 49a of the valve stem
49 is aligned with the containing hole 87 and the extension hole
82, and is inserted in the insertion hole 81. In contrast, in a
working condition, where the oil pressure in the oil pressure
chamber 75 is high, the slide pin 76 is moved to the left side in
FIG. 5, so as to stagger the containing hole 87 from the axes of
the insertion hole 81 and the extension hole 82, and to abut the
stem end 49a of the valve stem 49 on the abutment surface 88 of the
slide pin 76.
[0074] Here, the rotation of the slide pin 76 about its axis is
inhibited by the stopper pin 78. The stopper pin 78 pierces through
the slit 91 of the slide pin 76. Specifically, the stopper pin 78
is mounted to the pin holder 74 by piercing through the slide pin
76 while permitting the slide pin 76 to move in the axial
direction, so that the abutment of the stopper pin 78 on an inner
end closed portion of the slit 91 restricts the end of movement of
the slide pin 76 to the side of the oil pressure chamber 75.
[0075] Further, the rest discriminating magnetic sensor 71 is
mounted to the annular recessed portion 99 of the cylinder head 40
while fronting on the communication hole in the valve lifter 611
and on the opening 79b in the pin holder 76. The rest
discriminating magnetic sensor 71 is a sensor which detects the
distance ds from the rest discriminating magnetic sensor 71 through
the communication hole 100 and the opening 79b to a wall portion
76a of the slide pin 76. The sensor 71 includes a magnet and a
coil, and detects the distance ds by detecting a magnetic flux
variation generated when the slide pin 76, made of a metal, is
moved. A cable 71a for outputting the detection results is
connected to the rest discriminating magnetic sensor 71. The cable
71a is passed through an insertion hole formed in the cylinder head
40, and is connected to an ECU (cylinder number control unit) 70
(see FIG. 9) which will be described later. Incidentally, such a
rest discriminating sensor is not limited to the magnetic sensor;
there may be used a sensor for detecting the distance ds by use of
light, a sensor for detecting the distance ds by detecting a
variation in electrostatic capacity, a sensor for detecting the
distance ds by use of ultrasound, and the like.
[0076] As shown in FIGS. 2 and 3, the first and second exhaust
valves 471, 472 of the combustion chambers 42 are driven by an
exhaust-side valve operating device 68. The exhaust-side valve
operating device 68 has a camshaft 65 provided with a first
exhaust-side valve operating cams 641 corresponding respectively to
the first exhaust valves 471 and with second exhaust-side valve
operating cams 642 corresponding respectively to the second exhaust
valves 472. The exhaust side view of the device has bottomed hollow
cylindrical valve lifters 661 slidingly driven by the first
exhaust-side valve operating cams 641 and bottomed hollow
cylindrical valve lifters 662 slidingly driven by the second
exhaust-side valve operating cams 642.
[0077] The camshaft 65 has an axis orthogonal to the extensions of
the axes of the valve stems 51 of the first and second exhaust
valves 471, 472, and is rotatably supported between the cylinder
head 40 and the head cover 41 joined to the cylinder head 40, like
the camshaft 60 of the intake-side valve operating device 58. The
valve lifters 661 are slidably fitted in the cylinder head 40
coaxially with the axes of the valve stems 51 of the first exhaust
valves 471, and the outside surfaces of the closed ends of the
valve lifters 661 are in sliding contact with the first
exhaust-side valve operating cams 641.
[0078] In addition, the valve lifters 662 are slidably fitted in
the cylinder head 40 coaxially with the axes of the valve stems 51
of the second exhaust valves 472, and the outside surfaces of the
closed ends of the valve lifters 662 are in sliding contact with
the second exhaust-side valve operating cams 642.
[0079] The stem end of the valve stem 51 of the second exhaust
valve 472 abuts on the inside surface of the closed end of the
valve lifter 662 through the shim 67, and are normally opened and
closed by the second exhaust-side valve operating cam 642 during
the operation of the engine E. In addition, a valve stop mechanism
69 effects a change between action and inaction of the pressing
force exerted from the valve lifter 661 on the first exhaust valve
471 in the valve-opening direction, and brings the first exhaust
valve 471 into a resting state irrespective of the sliding of the
valve lifter 661 by putting the pressing force into an inactive
state in a specified operation range of the engine E, for example,
in a low load range such as a low speed operation range. The valve
stop mechanism 69 is provided between the stem ends 51a of the
valve stem 51 of the first exhaust valve 471 and the valve lifter
661. The valve stop mechanism 69 of the exhaust-side valve
operating device 68 is configured in the same manner as the valve
stop mechanism 63 (see FIG. 5) in the intake-side valve operating
device 58.
[0080] In the #3 cylinder, the valve stop mechanism 63 and the
valve stop mechanism 69, configured in the same manner as in the #4
cylinder, are provided for the second exhaust valve 472
(corresponding to a second exhaust valve port 452) and the second
intake valve 462 (corresponding to a second intake valve port 442),
while the first exhaust valve 471 and the first intake valve 461
are not provided with respective valve stop mechanisms 63, 69, in a
manner contrary to that in the #4 cylinder. Further, in the #1
cylinder and the #2 cylinder, the valve stop mechanism 63 and the
valve stop mechanism 69 are provided for all the intake valves 461,
462 and the exhaust valves 471, 472.
[0081] Therefore, since in the #1 cylinder and the #2 cylinder the
valve stop mechanisms 63, 69 are provided for all the engine
valves, these valve stop mechanisms 63, 69 function as a cylinder
resting mechanism, and a cylinder rest where all the engine valves
are in rest (the cylinders are rest-able cylinders) can be
performed. Additionally, in the #3 cylinder and the #4 cylinder, a
valve rest where one engine valve each on the intake side and the
exhaust side is in rest (the cylinders are normally operative
cylinders) can be performed.
[0082] As shown in FIG. 1, a side wall on the #4 cylinder side of
the cylinder head 40 is provided with a cam chain case C, and a cam
chain (not shown) for driving the camshafts 60, 65 of the
intake-side and exhaust-side valve operating devices 58, 68 are
contained in the cam chain case C. A side wall of the cylinder head
40 on the opposite side of the cam chain case C is provided with
connection ports PA, PB, PC of oil pressure control valves 113A,
113B, 113C for controlling the supply of the working oil to the
valve stop mechanisms 63, 69 (see FIGS. 2 and 3) of the intake-side
and exhaust-side valve operating devices 58, 68.
[0083] The connection port PA is connected to a working oil supply
passage 103A which extends in the cylinder head 40 between a
central portion in the front-rear direction of the cylinder head 40
to each intake valve port along the longitudinal direction to the
layout position of the second intake valve port 442 of the #2
cylinder and which is branched toward the second intake valve port
442 of the #2 cylinder and the second exhaust valve port 452 of the
#2 cylinder.
[0084] The connection port PB is connected to a working oil supply
passage 103B which extends in the cylinder head 40 between a
central portion in the front-rear direction of the cylinder head 40
to each exhaust valve port along the longitudinal direction to the
layout position of the first exhaust valve port 451 of the #1
cylinder and which is branched toward the first exhaust valve port
451 of the #1 cylinder and the first intake valve port 441 of the
#1 cylinder.
[0085] The connection port PC is connected to a working oil supply
passage 103C which extends in the other side wall of the cylinder
head 40 along the longitudinal direction to the layout position of
the first exhaust valve port 451 of the #4 cylinder and which is
branched toward the first exhaust valve port 451 of the #4
cylinder, the second exhaust valve port 452 of the #3 cylinder, the
first exhaust valve port 451 of the #2 cylinder and the second
exhaust valve port 452 of the #1 cylinder.
[0086] In addition, in correspondence with the working oil supply
passage 103C, a working oil supply passage 103C' is formed in the
rear side wall of the cylinder head 40 along the longitudinal
direction of the cylinder head 40 to the layout position of the
first intake valve port 441 of the #4 cylinder, and the working oil
supply passage 103C and the working oil supply passage 103C' are
connected to each other through a crossing passage 103X.
Additionally, the working oil supply passage 103C' is branched to
be connected to the first intake valve port 441 of the #4 cylinder,
the second intake valve port 442 of the #3 cylinder, the first
intake valve port 441 of the #2 cylinder and the second intake
valve port 442 of the #1 cylinder. Therefore, in the #1 cylinder
and the #2 cylinder, among the #1 cylinder, the #2 cylinder and the
#3 cylinder, i.e., the cylinders located on the opposite side of
the cam chain case C, all the engine valves consisting of the first
intake valve 461, the second intake valve 462, the first exhaust
valve 471 and the second exhaust valve 472 are configured to be
rest-able.
[0087] When solenoids (not shown) are turned ON, the oil pressure
control valves 113A, 113B, 113C are so operated that a working oil
pressure is exerted on the connection ports PA, PB, PC via an
in-port IN; when the solenoids are turned OFF, the exerted oil
pressure is led to a drain port D, and the oil pressure control
valves 113A, 113B, 113C are so operated that the working oil is
supplied to the valve stop mechanisms 63, 69 through the working
oil supply passage 103A, the working oil supply passage 103B, and
the working oil supply passage 103C (103C'). Incidentally, in FIG.
1, symbol IN denotes an in-port, OUT denotes an out-port, and D
denotes a drain port.
[0088] As shown in FIG. 9, the oil pressure control valves 113A,
113B, 113C are supplied with the working oil which is reserved in
an oil pan 120. A main oil pressure passage 122 fitted with a pump
121 is connected to the oil pan 120, and, on the discharge side of
the pump 121, a branch passage 123 connected to the oil pressure
control valves 113A, 113B, 113C is branched from the main oil
pressure passage 122. In addition, the drain ports D (see FIG. 1)
of the oil pressure control valves 113A, 113B, 113C are connected
to a drain passage 124 so that the working oil can be recovered
into the oil pan 120.
[0089] The control of the oil pressure control valves 113A, 113B,
113C is conducted by the ECU 70, which is an electronic control
unit, based on the handgrip opening .theta.g detected by a handgrip
opening sensor C the engine speed Ne, the rest discriminating
magnetic sensor 71 and the like. In addition, the ECU 70 controls
the throttle valve TH by outputting a turning command signal to
each of the motors 21A, 21B while detecting the throttle valve
opening by a throttle valve position sensor 22 so as to set optimum
the throttle valve opening based on the value detected by the
handgrip opening sensor G and the like. Further, fuel injection
amount at the injector 26 is regulated based on a control signal
from the ECU 70. Thus, the ECU 70 has means for changing over the
oil pressure control valves 113A, 113B, 113C, means for controlling
the throttle valve opening, and a means for controlling the fuel
injection amount.
[0090] Next, the valve rest and the cylinder rest conducted under
the control by the ECU 70 will be described, the description being
centered on the operations of the intake valves 461, 462 and the
exhaust valves 471, 472 provided with the valve stop mechanisms 63,
69.
[0091] As shown in FIG. 9, when the valve rest and the cylinder
rest are not conducted, the ECU 70 drives the throttle valve TH by
outputting the turning command signal to each of the motors 21A,
21B while detecting the throttle valve opening by the throttle
valve position sensor 22, based on the detection signals fed from
the handgrip opening sensor G and the like. In addition, the fuel
injection amount at the injector 26 is regulated based on the
control signal from the ECU 70.
[0092] The oil pressure chamber 75 of the valve stop mechanism 63
is supplied with the working oil via the working oil supply passage
103, whereby the return spring 77 is compressed, and the slide pin
76 is located on a comparatively left side in FIG. 9. Additionally,
the valve stop mechanism 69 on the exhaust side as shown in FIG. 2
is also configured so that the oil pressure of the working oil acts
on the slide pin 76.
[0093] Therefore, when the valve lifter 611 is slid by the pressing
force exerted from the intake-side valve operating device 58, the
pin holder 74 and the slide pin 76 are accordingly moved to the
side of the first intake valve 461, and, attendant on this, a
pressing force in the valve opening direction is exerted on the
first intake valve 461, whereby an air-fuel mixture is taken
through the first intake valve port 441 into the combustion chamber
42 (intake stroke). The mixture gas in the combustion chamber 42 is
compressed by the piston 38 (see FIG. 2) and is then ignited by a
spark plug (not shown) into combustion.
[0094] In addition, as shown in FIG. 2, when the valve lifter 661
is slid by a pressing force exerted from the exhaust-side valve
operating device 68, the pin holder 74 and the slide pin 76 are
accordingly moved to the side of the exhaust valve 471, and,
attendant on this, a pressing force in the valve opening direction
is exerted on the exhaust valve 471, whereby an exhaust gas is
exhaust through the first exhaust valve port 451 to the exhaust
port 19 (exhaust stroke).
[0095] The processing by the ECU 70 in the case where predetermined
conditions are fulfilled and the valve rest and cylinder rest are
conducted will be described based on a flow chart shown in FIG. 10.
First, the ECU 70 detects the handgrip opening .theta.g (step S1),
and the passage of current to the injector 26 is stopped, thereby
stopping the fuel supply (F1) (step S2). Thereafter, the exhaust
valves 471, 472 and the intake valves 461, 462 are rested (step
S3).
[0096] The resting of the exhaust valves 471, 472 and the intake
valves 461, 462 is carried out as follows.
[0097] After the completion of the exhaust stroke is confirmed by a
crank angle sensor (not shown) or the like, a control signal is
outputted to each of the oil pressure control valves 113A, 113B,
113C, to discharge the working oil from the oil pressure chamber 75
(see FIG. 5), and the exhaust valves 471, 472 are rested. The
resting of the exhaust valves 471, 472 is confirmed by use of the
rest discriminating magnetic sensor 71. When the above-mentioned
distance ds detected by the rest discriminating magnetic sensor 71
has reached a distance corresponding to the position where the
containing hole 87 and the insertion hole 81 are matched, the ECU
70 determines that the exhaust valves 471, 472 corresponding to the
rest discriminating magnetic sensor 71 has come to a rest.
[0098] After the resting of the exhaust valves 471, 472 is
confirmed, a control signal is outputted to each of the oil
pressure control valves 113A, 113B, 113C, to stop the intake valves
461, 462. The resting of the intake valves 461, 462 is also
conducted based on the distance ds detected by the rest
discriminating magnetic sensor 71 provided in the vicinity of the
stem end 49a of each of the intake valves 461, 462, in the same
manner as above.
[0099] Then, the throttle valve TH is put into a closed state by
driving the motors 21A, 21B (step S4), and the supply of electric
power to the spark plug is interrupted (step S5). The cutoff of
ignition is carried out for several cycles (in this embodiment, 10
cycles), and thereafter the ignition is reset. This makes it
possible to confirm the cylinder rest (resting of the cylinder)
with a predetermined timing, to prevent the temperature of the
spark plug from being lowered at the time of re-operation, and to
securely perform the cylinder re-operation with a predetermined
timing.
[0100] Under the above-mentioned control, the working oil is
discharged via the drain passage 124 as shown in FIG. 11, the slide
pin 76 is moved by the force of the return spring 77 so as to
reduce the oil pressure chamber 75, and the containing hole 87 is
matched to (aligned with) the insertion hole 81 in the pin holder
74. Even when the valve lifter 611 is moved toward the side of the
first intake valve 461 by the intake-side valve operating device 68
in this condition, the stem end 49a (see FIG. 5) of the valve stem
49 is received within the insertion hole 81 and the containing hole
87, and no pressing force is exerted on the first intake valve 461,
so that the first intake valve port 441 is kept closed.
[0101] In addition, the working oil is similarly discharged also
from the valve stop mechanism 69 on the exhaust side as shown in
FIG. 3, the containing hole 87 is matched to (aligned with) the
insertion hole 81 in the pin holder 74, and no pressing force is
exerted on the first exhaust valve 471, so that the first exhaust
valve port 451 is kept closed.
[0102] Next, the processing by the ECU 70 in the case of resetting
a cylinder in the resting state, the intake valves 461, 462 and the
exhaust valves 471, 472 will be described based on a flow chart
shown in FIG. 12.
[0103] First, the ECU 70 detects the handgrip opening .theta.g
(step S11), and brings the throttle valve TH into an open state by
driving the motors 21A, 21B while detecting the throttle valve
opening by the throttle valve position sensor 22, based on the
handgrip opening .theta.g (step S12).
[0104] Then, the intake valves 461, 462 and the exhaust valves 471,
472 are operated (step S13). The operations of the exhaust valves
471, 472 and the intake valves 461, 462 are conducted as
follows.
[0105] First, a control signal is outputted to each of the oil
pressure control valves 113A, 113B, 113C, whereby an oil pressure
is exerted on the slide pin 76 to move the slide pin 76, to operate
the first exhaust valve 471. The operations of the exhaust valves
471, 472 are confirmed by use of the rest discriminating magnetic
sensor 71. When the distance ds detected by the rest discriminating
magnetic sensor 71 has come to be a distance corresponding to a
position where the containing hole 87 and the insertion hole 81 are
not aligned with each other, the ECU 70 determines that the exhaust
valve 471, 472 corresponding to the rest discriminating magnetic
sensor 71 has changed over to an operative state.
[0106] After the operations of the exhaust valves 471, 472 is
confirmed, a control signal is outputted from the ECU 70 to each of
the oil pressure control valves 113A, 113B, 113C (see FIG. 1),
whereby the intake valves 461, 462 are operated. The operations of
the intake valves 461, 462 are confirmed based on the distance ds
detected by the rest discriminating magnetic sensor 71, in the same
manner as above. After the operations of the intake valves 461, 462
are confirmed, the injector 16 is operated, to start the fuel
supply (step S14). Incidentally, in this instance, the cutoff of
ignition has been reset, so that the engine is driven by starting
the fuel supply.
[0107] Now an explanation is provided as to how the engine valves
(the exhaust valves 471, 472 and the intake valves 461, 462) are
operated according to the handgrip opening .theta.g and how the
throttle valve TH is opened to increase the engine output will be
described, based on FIGS. 14 to 16. Incidentally, in FIGS. 14 to
16, the hatched valves are the engine valves in the resting state.
When the intake valves 461, 462 and the exhaust valves 471, 472,
which are the engine valves, are all rested (all valve rest), the
cylinder rest results. Here, the first intake valve 461 and the
first exhaust valve 472 are disposed on a diagonal line, while the
second intake valve 462 and the second exhaust valve 472 are
disposed on a second diagonal line, the adjacent exhaust valves
471, 472 of the two adjacent cylinders are configured as operative
valves, and a secondary air introduction valve (exhaust device) Al
is provided between the exhaust valves 471, 472 (exclusive of the
portion between the #2 cylinder and the #3 cylinder).
[0108] As shown in FIG. 13, in the engine E of this embodiment, the
cylinders to be operated and the throttle valve opening in each
cylinder group are determined uniquely, on the basis of the
handgrip opening .theta.g best representing the driver's intention
to accelerate. Specifically, the number of the cylinder groups to
be operated is increased with an increase in at least the handgrip
opening .theta.g. In addition, whether the cylinder is to be rested
or operated is determined based on whether the engine speed Ne is
higher or lower than a threshold value a. These are controlled by
the ECU 70.
[0109] First, the case where the engine speed Ne is lower than a
threshold value a will be described. In this case, 2-valve
operation for a low load time is established in which the
individual cylinder groups, here, the cylinder group composed of
the #3 cylinder and the #4 cylinder, the cylinder group composed of
the #2 cylinder (in this embodiment, a single cylinder), and the
cylinder group composed of the #1 cylinder (in this embodiment, a
single cylinder) are each operated by use of single intake and
exhaust valves.
[0110] First, in the range from an idling condition to the
condition where the handgrip opening .theta.g is an opening
.theta.g2, the cylinder rest (all valve rest) is conducted in the
#1 cylinder and the #2 cylinder, the valve rest is conducted in the
#3 cylinder and the #4 cylinder, and, in this condition, the
throttle valve opening is gradually increased with an increase in
the handgrip opening .theta.g.
[0111] In other words, in the condition shown in FIG. 14, the
throttle valve TH for the #3 cylinder and the #4 cylinder is
gradually opened (2-cylinder 2-valve operation shown in FIG. 13).
Here, the average of an increase ratio (dTH/d.theta.g) of the
throttle valve opening to the handgrip opening in the #3 cylinder
and the #4 cylinder is set higher than the average of the increase
ratio of the throttle valve opening to the handgrip opening in the
#2 cylinder.
[0112] Next, when the handgrip opening .theta.g comes to be
.theta.g2, cylinder rest (all valve rest) is conducted in the #1
cylinder, while valve rest is conducted in the #2 cylinder, the #3
cylinder, and the #4 cylinder, and, in this condition, the throttle
valve TH of the #2 cylinder is started to open, in addition to the
#3 cylinder and the #4 cylinder in which the throttle valve opening
thereafter increases continuously. That is, in the condition shown
in FIG. 15, the throttle valve TH in the #2 cylinder, in addition
to the #3 cylinder and the #4 cylinder, is gradually opened
(3-cylinder 2-valve operation shown in FIG. 13). Here, the average
of the increase ratio of the throttle valve opening to the handgrip
opening in the #2 cylinder is set to be higher than that in the #1
cylinder in which the throttle valve is next started to open.
[0113] Then, when the handgrip opening .theta.g2 becomes an opening
.theta.g1, valve rest is conducted in all cylinders from the #1
cylinder to the #4 cylinder, and, in this condition, the throttle
valve TH of the #1 cylinder is started to open, in addition to the
#3 cylinder, the #4 cylinder, and the #2 cylinder in which the
throttle valve thereafter increases continuously. Namely, in the
condition shown in FIG. 16, the throttle valve TH in the #1
cylinder, in addition to the #3 cylinder and the #4 cylinder, is
gradually opened (4-cylinder 2-valve operation shown in FIG.
13).
[0114] On the other hand, when the engine speed Ne reaches or
exceeds the threshold value a, 4-valve operation for a high load
time is established in which each cylinder group is operated with
two intake valves and two exhaust valves. First, in the condition
where valve rest is not conducted in the #3 cylinder, the #4
cylinder, the #2 cylinder and the #1 cylinder, the throttle valve
opening is sequentially increased according to the handgrip opening
.theta.g, and a throttle valve opening best suited to the driver's
intention to accelerate is set. That is, in the condition shown in
FIG. 17, the throttle valve TH is gradually opened and sequentially
in the order of the #3 cylinder, the #4 cylinder, the #2 cylinder
and the #1 cylinder (4-cylinder 4-valve operation shown in FIG.
13). Therefore, the throttle valve openings in the #3 cylinder and
the #4 cylinder, in the #2 cylinder, and in the #1 cylinder are
different, except for the fully opened time and the fully closed
time of the throttle valve TH.
[0115] Therefore, according to the above-described embodiment, the
throttle valve openings in the #3 cylinder and the #4 cylinder, in
the #2 cylinder, and in the #1 cylinder are different, except for
the fully opened time and the fully closed time of the throttle
valve TH, and the throttle valve TH in the next cylinder group is
opened before the throttle valve opening in the former cylinder
group reaches the fully opened state. Therefore, as compared to the
case where the throttle valves in all cylinder groups are
simultaneously opened to thereby increase the output, the engine E
can be operated with high combustion efficiency, which can
contribute to improvement of fuel consumption. Among others, since
the throttle valve in the next cylinder group is opened before the
throttle valve opening in the former cylinder group reaches the
fully opened state, it is possible to eliminate the step in output,
and to realize a smooth operation.
[0116] In addition, in this embodiment, the average of the increase
ratio (dTH/d.theta.g) of the throttle valve opening to the handgrip
opening in the #3 cylinder and the #4 cylinder whose throttle
valves are opened first is set higher than the average of the
increase ratio of the throttle valve opening to the handgrip
opening in the #2 cylinder whose throttle opening is next started
to open. Further, the average of the increase ratio of the throttle
valve opening to the handgrip opening in the #2 cylinder is set
higher than that in the #1 cylinder whose throttle valve is next
started to open. In other words, the increase ratio in a cylinder
whose throttle valve is opened first at the time of starting the
grip operation is set to be high, and the increase ratios in the
cylinders whose throttle valves are thereafter opened sequentially
are set to be gradually lowered. Referring to FIG. 13, the
inclinations of the three lines are so set that the inclination is
greater as the line is located on the more left side.
[0117] Therefore, since the increase ratio is high in a low load
range, by bringing the throttle valve opening to the fully opened
state earlier, it is possible to operate in the range with a higher
load factor, and to reduce the pumping loss, so that an improvement
in fuel consumption can be contrived.
[0118] Since specified valves are rested and 2-valve operation is
conducted at a low load time, it is possible, at the low load time,
to limit the intake air amount and bring the throttle valve to the
fully opened state earlier, and thereby to generate an intake
swirl. As a result, the engine can be operated in a high load
factor range which is advantageous in view of improvement of fuel
consumption. In short, a swirl can be easily generated in the
cylinder by the first intake valve 461 and the first exhaust valve
471 which are disposed on a diagonal line or by the second intake
valve 462 and the second exhaust valve 472 which are disposed on a
diagonal line.
[0119] Since it is possible to perform an independent throttle
valve control on the basis of each cylinder group by use of
independent throttle valves, the need for a high response
performance in driving the throttle valve TH is eliminated, and
output variations at the time of changing over the number of
operative cylinders can be suppressed. Additionally, the need for
performing an output variation suppressing control according to
other controlled variable(s) is eliminated, and the control is
simplified.
[0120] Further, since the number of cylinders is varied based on at
least the handgrip opening .theta.g, the fuel consumption can be
improved while achieving an output demanded by the driver, by
reading the driver's intention from the operation variable.
[0121] In addition, since the number of cylinders can be varied
according to not only the grip operation but also the engine speed
Ne, it is possible to appropriately enhance the load factor of each
cylinder, and to achieve compatibility between engine output and
fuel consumption. Additionally, in a range where the handgrip
opening .theta.g is small and the engine speed Ne is high,
specifically, at the time of engine brake when the engine speed is
not less than the threshold value a or the like times, the number
of operative cylinders is four, so that an appropriate engine brake
can be secured.
[0122] Further, since cylinder rest can be realized by resting the
intake valves 461, 462 and the exhaust valves 471, 472, the pumping
loss can be reduced, and an improvement in fuel consumption can be
contrived. In addition, since the number of operative ones of the
intake valves 461, 462 and the exhaust valves 471, 472 can be
changed over according to the engine speed Ne, the output can be
made appropriate. Additionally, since the motors 21A, 21B, the
throttle valve position sensor 22 and the like which are driven and
controlled by the ECU 70 are provided for each of the cylinder
groups, the output variations at the time of changing over the
valves can be suppressed.
[0123] In addition, since the secondary air introduction valve A1
is provided between the adjacent exhaust valves 471, 472 of the two
adjacent cylinders, the layout position of the secondary air
introduction valve A1 can be made compact.
[0124] Additionally, since it is possible to operate in a range
where the load factor of each cylinder is high by increasing the
number of cylinders from two cylinders by one cylinder at a time,
fuel consumption can be improved also from this point of view.
[0125] The present invention is not limited to the above-described
embodiment; while the invention has been described taking a
motorcycle as an example, it can be applied also to four-wheeled
vehicles. In that case, acceleration pedal opening can be used in
place of handgrip opening. In addition, the present invention is
not limited to 4-cylinder engine, and the combination of cylinders
and the number of cylinder groups can be set freely; for example,
the invention is applicable to a 6-cylinder engine, where three of
the cylinders constitute a cylinder group, two of the cylinders
constitute another cylinder group, and the remaining one of the
cylinders singly constitutes a cylinder group. The above-mentioned
valve stop mechanism is a mere example, and a valve stop mechanism
of the type in which valve rest is achieved by use of a rocker arm
can be adopted. Additionally, all cylinders may be put into all
valve rest. Further, while the description has been made of the
case where 4-cylinder operation is established when the engine
speed Ne in 2-cylinder operation has exceeded the threshold value
a, various modes can be adopted; for example, transition from
2-cylinder operation to 3-cylinder operation and further to
4-cylinder operation according to the engine speed Ne may be
adopted.
[0126] While a working example of the present invention has been
described above, the present invention is not limited to the
working example described above, but various design alterations may
be carried out without departing from the present invention as set
forth in the claims.
* * * * *