U.S. patent application number 12/369229 was filed with the patent office on 2009-08-20 for variable air intake system.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Tsuyoshi KANDA.
Application Number | 20090205596 12/369229 |
Document ID | / |
Family ID | 40896876 |
Filed Date | 2009-08-20 |
United States Patent
Application |
20090205596 |
Kind Code |
A1 |
KANDA; Tsuyoshi |
August 20, 2009 |
VARIABLE AIR INTAKE SYSTEM
Abstract
A valve closing side engaging groove is formed in a
circumferential surface of a collar of a clutch between an optimum
angular position, which implements a most effective valve angle for
making the maximum fuel consumption improving effect, and a valve
closing side least effective angular position, which implements a
valve closing side least effective valve angle. Similarly, a valve
opening side engaging recess is formed in the circumferential
surface of the collar between the optimum angular position and a
valve opening side least effective angular position, which
implements a valve opening side least effective valve angle. Each
of the grooves is engageable with a roller to securely hold the
roller in corporation with a driven-side rotator to limit rotation
of the driven-side rotator in a deenergized state of a motor.
Inventors: |
KANDA; Tsuyoshi; (Obu-city,
JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
40896876 |
Appl. No.: |
12/369229 |
Filed: |
February 11, 2009 |
Current U.S.
Class: |
123/90.15 |
Current CPC
Class: |
F02D 11/10 20130101;
F02D 9/1065 20130101; F02D 9/1095 20130101; F02B 31/06 20130101;
F02D 9/103 20130101 |
Class at
Publication: |
123/90.15 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 20, 2008 |
JP |
2008-38882 |
Claims
1. A variable air intake system for an internal combustion engine,
comprising: an electric motor that is rotated to generate a
rotational force in an energized state of the electric motor; a
valve that is placed in an air intake passage of the internal
combustion engine and is rotated by the rotational force
transmitted from the electric motor to adjust intake air supplied
to the internal combustion engine through the air intake passage;
and a clutch that is placed between the electric motor and the
valve to enable transmission of the rotational force from the
electric motor to the valve and to disable transmission of a
rotational force from the valve to the electric motor, wherein: the
clutch includes: a driving-side rotator that is rotated by the
rotational force transmitted from the electric motor and includes a
plurality of circumferential side engagement releasing projections,
each of which circumferentially projects from a corresponding
adjacent part of the driving-side rotator that is adjacent to the
circumferential side engagement releasing projection; a driven-side
rotator that is coaxial with the driving-side rotator and is
rotated by the driving-side rotator upon circumferential engagement
with the driving-side rotator to rotate the valve in the energized
state of the electric motor; an annular collar that is
non-rotatably held and has a circumferential surface, which is
coaxial with the driven-side rotator, wherein a radial gap is
formed between an engaging portion of the driven-side rotator and
the circumferential surface of the collar and includes first and
second circumferential side gap sections and a circumferentially
intermediate gap section, which are arranged in such a manner that
the circumferentially intermediate gap section is circumferentially
placed between the first and second circumferential side gap
sections and has a radial size larger than a radial size of any of
the first and second circumferential side gap sections; and an
engageable element that is circumferentially placed between the
first and second circumferential side gap sections in the radial
gap, wherein a radial size of the engageable element is smaller
than the radial size of the circumferentially intermediate gap
section and is larger than the radial size of any of the first and
second circumferential side gap sections, and the engageable
element is circumferentially displaceable by a corresponding one of
the plurality of circumferential side engagement releasing
projections at a time of driving the driven-side rotator by the
driving-side rotator; the clutch and the valve are synchronized to
satisfy all of the following conditions: when the driving-side
rotator is rotated to rotate the driven-side rotator and thereby to
place the engageable element in a first angular position along the
circumferential surface of the collar, the valve is placed in a
most effective valve angle, at which a fuel consumption improving
effect of the intake air supplied from the valve to the internal
combustion engine through the air intake passage is maximized; when
the driving-side rotator is rotated to rotate the driven-side
rotator and thereby to displace the engageable element in a first
circumferential direction from the first angular position to a
second angular position along the circumferential surface of the
collar, the valve is rotated in a valve closing direction from the
most effective valve angle to a valve closing side least effective
valve angle, at which the fuel consumption improving effect of the
intake air supplied from the valve to the internal combustion
engine through the air intake passage is reduced to zero; and when
the driving-side rotator is rotated to rotate the driven-side
rotator and thereby to displace the engageable element in a second
circumferential direction, which is opposite from the first
circumferential direction, from the first angular position to a
third angular position along the circumferential surface of the
collar, the valve is rotated in a valve opening direction from the
most effective valve angle to a valve opening side least effective
valve angle, at which the fuel consumption improving effect of the
intake air supplied from the valve to the internal combustion
engine through the air intake passage is reduced to zero; a valve
closing side engaging recess is formed in the circumferential
surface of the collar between the first angular position and the
second angular position and is engageable with the engageable
element to securely hold the engageable element in cooperation with
the engaging portion of the driven-side rotator in the de-energized
state of the electric motor; and a valve opening side engaging
recess is formed in the circumferential surface of the collar
between the first angular position and the third angular position
and is engageable with the engageable element to securely hold the
engageable element in cooperation with the engaging portion of the
driven-side rotator in the de-energized state of the electric
motor.
2. The variable air intake system according to claim 1, further
comprising a speed reducer that is placed between the electric
motor and the valve to reduce a rotational speed of rotation, which
is originated from the electric motor and is conducted to the speed
reducer, wherein a speed reduction ratio G of the speed reducer
satisfies relationships of .gamma.1/G.ltoreq..alpha. and
.gamma.2/G.ltoreq..beta. where: .gamma.1 denotes an angular
difference between the first angular position and an angular
position of the valve closing side engaging recess along the
circumferential surface of the collar; .alpha. denotes an angular
difference between the most effective valve angle and the valve
closing side least effective valve angle; .gamma.2 denotes an
angular difference between the first angular position and an
angular position of the valve opening side engaging recess along
the circumferential surface of the collar; and .beta. denotes an
angular difference between the most effective valve angle and the
valve opening side least effective valve angle.
3. The variable air intake system according to claim 1, wherein:
the collar is placed radially outward of the driving-side rotator
and the driven-side rotator; and the circumferential surface of the
collar is an inner circumferential surface of the collar.
4. The variable air intake system according to claim 1, wherein the
engageable element is a roller, which is rollable along the
circumferential surface of the collar.
5. The variable air intake system according to claim 4, wherein
each of the valve closing side engaging recess and the valve
opening side engaging recess is in a form of a groove, into which a
portion of an outer peripheral surface of the roller is
engageable.
6. The variable air intake system according to claim 1, wherein:
the engageable element has a circular cross section; each of the
valve closing side engaging recess and the valve opening side
engaging recess has an arcuate surface; and a radius of curvature
of the arcuate surface of each of the valve closing side engaging
recess and the valve opening side engaging recess is generally the
same or slightly larger than that of the circular cross section of
the engageable element.
7. The variable air intake system according to claim 1, wherein an
optimal position engaging recess is formed in the circumferential
surface of the collar at the first angular position and is
engageable with the engageable element to securely hold the
engageable element in cooperation with the engaging portion of the
driven-side rotator in the de-energized state of the electric
motor.
8. The variable air intake system according to claim 1, wherein:
the engageable element is positionable in a securely engaged state
when the engageable element is circumferentially moved from the
circumferentially intermediate gap section toward one of the first
and second circumferential side gap sections and is securely held
between the engaging portion of the driven-side rotator and the
circumferential surface of the collar upon rotation of the
driven-side rotator induced by the rotational force transmitted
from the valve in a de-energized state of the electric motor; and
the engageable element is positionable in a released state when the
engageable element held in the securely engaged state is
circumferentially pushed by one of the plurality of circumferential
side engagement releasing projections of the driving-side rotator
toward the circumferentially intermediate gap section to release
the engageable element from the securely engaged state and thereby
to permit integral rotational movement of the driving-side rotator,
the driven-side rotator and the engageable element in the energized
state of the electric motor.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2008-38882 filed on Feb.
20, 2008.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a variable air intake
system, which includes a clutch that enables transmission of a
rotational force of an electric motor toward a valve and disables
transmission of a rotational force of the valve toward the electric
motor.
[0004] 2. Description of Related Art
[0005] In a known variable air intake system, a valve is placed in
an air intake passage of an internal combustion engine
(hereinafter, referred to as an engine). An opening degree of the
valve is held in an intermediate opening degree of the valve to
generate, for example, a tumble flow or swirl flow in a combustion
chamber of the engine to improve a combustion state of fuel in the
combustion chamber. Thereby, purification of exhaust gas of the
engine at the time of engine start can be improved, and the fuel
consumption improving effect can be enhanced.
[0006] In the above-described technique, the opening degree of the
valve is held constant at the time of implementing the above
effects, and this opening degree of the valve is maintained through
the energization of the electric motor. Thus, the electric power is
required to maintain the opening degree of the valve as long as the
engine is operated.
[0007] In order to minimize the electric power consumption, it is
conceivable to use a clutch, which conducts a rotational force from
a driving-side rotator to a driven-side rotator and does not
conduct a rotational force from the driven-side rotator to the
driving-side rotator while transmitting such a rotational force to
a collar (serving as a stationary member). With this clutch, the
energization of the motor can be stopped at the time of maintaining
the opening degree of the valve. For example, WO 00/08349A1
(corresponding to U.S. Pat. No. 6,575,277B1), WO 00/08350A1
(corresponding to U.S. Pat. No. 6,789,443B1) and JP 2001-214946A
teach various types of clutches.
[0008] In the case of the WO 00/08349A1 (corresponding to U.S. Pat.
No. 6,575,277B1) or WO 00/08350A1 (corresponding to U.S. Pat. No.
6,789,443B1), the collar is placed radially outward of the
driven-side rotator. In contrast, in the case of JP 2001-214946A,
the collar is placed radially inward of the driven-side
rotator.
[0009] However, in the case of the clutch recited in WO 00/08349A1
(corresponding to U.S. Pat. No. 6,575,277B1), WO 00/08350A1
(corresponding to U.S. Pat. No. 6,789,443B1) or JP 2001-214946A,
the clutch is used in a power window system of a vehicle. When such
a clutch is used for the valve of the variable air intake system, a
pressure pulsation, which occurs in the intake passage, causes
application of a rotational force (specifically, a rotational force
caused by large vibration, large load, large pressure pulsation or
the like) to the valve, so that the holding state of the valve (the
engaged state of the clutch) may possibly be released. That is, the
rotation of the valve cannot be limited by the clutch.
[0010] In view of the above disadvantage, a plurality of recesses
may be provided in an engaging surface of the collar, to which
rollers are locked. The rollers are fitted into the corresponding
recesses of the collar, so that the holding force (the engaging
force of the clutch) for holding the valve in place is improved.
Therefore, even when the rotational force is applied to the valve
due to the pressure pulsation, the holding state of the valve is
not unintentionally released. This technique is recited in, for
example, JP 2007-198584A (corresponding to US 200710144854A1).
[0011] In the case of JP 2007-198584A (corresponding to US
2007/0144854A1), the recesses are provided in the collar to
increase the holding force for holding the valve. However, the
locations of the recesses are not set to maintain an effective
opening degree range of the valve, which enables the improvement of
the fuel consumption.
[0012] Specifically, in the case of the variable air intake system,
the opening degree of the valve needs to be maintained within the
effective opening degree range shown, for example, in FIG. 6 (the
opening degree range of the valve, in which the fuel consumption
improving effect is larger than zero and is indicated as "required
accuracy" in FIG. 6), which enables the improvement of the fuel
consumption of the engine. However, in the previously proposed
techniques discussed above, the above point is not concerned.
SUMMARY OF THE INVENTION
[0013] The present invention addresses the above disadvantage.
According to the present invention, there is provided a variable
air intake system for an internal combustion engine. The variable
air intake system includes an electric motor, a valve and a clutch.
The electric motor is rotated to generate a rotational force in an
energized state of the electric motor. The valve is placed in an
air intake passage of the internal combustion engine and is rotated
by the rotational force transmitted from the electric motor to
adjust intake air supplied to the internal combustion engine
through the air intake passage. The clutch is placed between the
electric motor and the valve to enable transmission of the
rotational force from the electric motor to the valve and to
disable transmission of a rotational force from the valve to the
electric motor. The clutch includes a driving-side rotator, a
driven-side rotator, an annular collar and an engageable element.
The driving-side rotator is rotated by the rotational force
transmitted from the electric motor and includes a plurality of
circumferential side engagement releasing projections, each of
which circumferentially projects from a corresponding adjacent part
of the driving-side rotator that is adjacent to the circumferential
side engagement releasing projection. The driven-side rotator is
coaxial with the driving-side rotator and is rotated by the
driving-side rotator upon circumferential engagement with the
driving-side rotator to rotate the valve in the energized state of
the electric motor. The annular collar is non-rotatably held and
has a circumferential surface, which is coaxial with the
driven-side rotator, wherein a radial gap is formed between an
engaging portion of the driven-side rotator and the circumferential
surface of the collar and includes first and second circumferential
side gap sections and a circumferentially intermediate gap section,
which are arranged in such a manner that the circumferentially
intermediate gap section is circumferentially placed between the
first and second circumferential side gap sections and has a radial
size larger than a radial size of any of the first and second
circumferential side gap sections. The engageable element is
circumferentially placed between the first and second
circumferential side gap sections in the radial gap. A radial size
of the engageable element is smaller than the radial size of the
circumferentially intermediate gap section and is larger than the
radial size of any of the first and second circumferential side gap
sections, and the engageable element is circumferentially
displaceable by a corresponding one of the plurality of
circumferential side engagement releasing projections at a time of
driving the driven-side rotator by the driving-side rotator.
[0014] The clutch and the valve are synchronized to satisfy all of
the following conditions. That is, when the driving-side rotator is
rotated to rotate the driven-side rotator and thereby to place the
engageable element in a first angular position along the
circumferential surface of the collar, the valve is placed in a
most effective valve angle, at which a fuel consumption improving
effect of the intake air supplied from the valve to the internal
combustion engine through the air intake passage is maximized.
Also, when the driving-side rotator is rotated to rotate the
driven-side rotator and thereby to displace the engageable element
in a first circumferential direction from the first angular
position to a second angular position along the circumferential
surface of the collar, the valve is rotated in a valve closing
direction from the most effective valve angle to a valve closing
side least effective valve angle, at which the fuel consumption
improving effect of the intake air supplied from the valve to the
internal combustion engine through the air intake passage is
reduced to zero. Furthermore, when the driving-side rotator is
rotated to rotate the driven-side rotator and thereby to displace
the engageable element in a second circumferential direction, which
is opposite from the first circumferential direction, from the
first angular position to a third angular position along the
circumferential surface of the collar, the valve is rotated in a
valve opening direction from the most effective valve angle to a
valve opening side least effective valve angle, at which the fuel
consumption improving effect of the intake air supplied from the
valve to the internal combustion engine through the air intake
passage is reduced to zero.
[0015] A valve closing side engaging recess is formed in the
circumferential surface of the collar between the first angular
position and the second angular position and is engageable with the
engageable element to securely hold the engageable element in
cooperation with the engaging portion of the driven-side rotator in
the de-energized state of the electric motor. A valve opening side
engaging recess is formed in the circumferential surface of the
collar between the first angular position and the third angular
position and is engageable with the engageable element to securely
hold the engageable element in cooperation with the engaging
portion of the driven-side rotator in the de-energized state of the
electric motor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention, together with additional objectives, features
and advantages thereof, will be best understood from the following
description, the appended claims and the accompanying drawings in
which:
[0017] FIG. 1 is a diagram showing a valve angle of a valve and an
angular position of a roller along a collar of a clutch with
respect to a fuel consumption improving rate according to an
embodiment of the present invention;
[0018] FIG. 2A is a schematic view showing the clutch according to
the embodiment;
[0019] FIG. 2B is a partial enlarged view showing the roller held
in a groove of the collar in the clutch;
[0020] FIG. 3A is a perspective view showing an electric motor, the
clutch and a speed reducer according to the embodiment;
[0021] FIG. 3B is a schematic cross sectional view showing the
clutch received in a clutch housing;
[0022] FIG. 4 is a diagram showing a relationship between a fuel
consumption deteriorating rate caused by a pumping loss and an
opening degree of the valve according to the embodiment;
[0023] FIG. 5 is a diagram showing a relationship between a fuel
consumption improving rate caused by EGR and an opening degree of
the valve according to the embodiment;
[0024] FIG. 6 is a diagram showing a relationship between a fuel
consumption improving rate and an opening degree of the valve
according to the embodiment; and
[0025] FIG. 7 is a schematic view showing the valve placed in an
air intake passage according to the embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0026] An embodiment of the present invention will be described
with reference to FIGS. 1 to 7.
[0027] With reference to FIG. 7, a variable air intake system of
the present embodiment is a system that changes an opening degree
of a valve 100, which is placed in an air intake passage 111 of an
internal combustion engine. The valve 100 has a hinged valve
structure and thereby has a plate-shaped opening and closing member
(valve plate) 100a and a valve drive shaft 100b. The valve drive
shaft 100b extends through a lower end portion of the opening and
closing member 100a. More specifically, each corresponding opening
and closing member 100a is placed in the air intake passage 111 of
a corresponding one of tubes of an intake manifold 110 of the
engine in the present instance. For instance, in a case of a four
cylinder engine, four opening and closing members 100a are placed
in four tubes, respectively, of the intake manifold 110, and the
single valve drive shaft 100b extends through the lower end
portions of the opening and closing members 100a to integrally
drive the opening and closing members 100a in a valve closing
direction CL or a valve opening direction OP to control the intake
air supplied from the intake manifold 110 to combustion chambers
(located on the left side in FIG. 7) of the engine. In the
following description, only one of the opening and closing members
100a along with the valve drive shaft 100b will be described for
the sake of simplicity.
[0028] The variable air intake system includes the above described
valve 100 as well as an electric motor 1, a speed reducer 2 and a
clutch 3 shown in FIG. 3A. The motor 1 is rotatable in a forward
direction or a reverse direction upon energization thereof (in an
energized state). The speed reducer 2 reduces the rotational speed
of the rotation transmitted from the motor 1 and outputs the
rotation of the reduced rotational speed from an output shaft 24 to
the valve drive shaft 100b of the valve 100 to drive the same. The
clutch 3 is interposed between the motor 1 and the speed reducer 2.
The energization of the motor 1 is controlled by a control device
(such as an electronic control unit that is abbreviated as
ECU).
[0029] As discussed above, the valve 100 has the hinged valve
structure, in which the valve drive shaft 100b is provided at one
side of the plate-shaped opening and closing member 100a that is
configured and positioned to limit an increase in a resistance of
the air in the air intake passage 111 at the time of full opening
of the valve 100.
[0030] Now, the basic structure of the clutch 3 will be
described.
[0031] With reference to FIGS. 2A to 3B, the clutch 3 includes a
driving-side rotator 4, a driven-side rotator 5, an annular collar
6 and a plurality of rollers (serving as engageable elements) 7.
The driving-side rotator 4 is rotated by the rotational force of
the motor 1. The driven-side rotator 5 is driven by the
driving-side rotator 4 through circumferential engagement
therebetween. An inner circumferential surface 8 of the collar 6 is
coaxially placed relative to the driving-side rotator 4 and the
driven-side rotator 5. The rollers 7 are radially placed between
the driven-side rotator 5 and the collar 6. The respective
components of the clutch 3 may be made of metal or rigid resin.
[0032] The collar 6 of the present embodiment is configured into a
cylindrical body, which is placed radially outward of the
driving-side rotator 4 and the driven-side rotator 5 to surround
the same. The inner circumferential surface 8 of the collar 6
serves as an engaging surface and extends along an imaginary
circle, a center of which coincides with the rotational axis of the
driving-side rotator 4 and of the driven-side rotator 5. The collar
6 is non-rotatably fixed to a clutch housing 9.
[0033] In the present embodiment, although the collar 6 is
installed in the clutch housing 9, the collar 6 may be formed
integrally with the clutch housing 9.
[0034] The driven-side rotator 5 is coupled with an input shaft (an
output side of the clutch 3) 11 of the speed reducer 2 and has one
or more (three in this embodiment) fan shaped-portions (engaging
portions) 12, each of which extends radially outward. A radially
outer surface 13 of each fan-shaped portion 12 is a planar surface
that is generally parallel to a tangential direction, which is
tangential to the cylindrical inner circumferential surface 8 of
the collar 6.
[0035] With the above construction, a radial gap G is defined
between the radially outer surface 13 of each fan-shaped portion 12
of the driven-side rotator 5 and the inner circumferential surface
8 of the collar 6. In the gap G, one large radial gap
(circumferentially intermediate gap section) L1 and two small
radial gaps (first and second circumferential side gap sections) L2
are radially defined between the radially outer surface 13 of each
fan-shaped portion 12 of the driven-side rotator 5 and the inner
circumferential surface 8 of the collar 6. The small radial gaps L2
are located on opposed circumferential sides, respectively, of the
large radial gap L1. A radial size (radial extent) of each of the
small radial gaps L2 is smaller than that of the large radial gap
L1.
[0036] Each roller 7 is configured into a cylindrical body and is
placed in the gap G, i.e., is radially placed between the radially
outer surface 13 of the corresponding fan-shaped portion 12 and the
inner circumferential surface 8 of the collar 6. A corresponding
holder 14 rotatably holds the roller 7 at opposed circumferential
sides of the roller 7 and is rotatable relative to the driven-side
rotator 5 about the rotational axis of the driven-side rotator
5.
[0037] An outer diameter (a radial size) L3 of the roller 7 is
smaller than the radial size of the large radial gap L1 and is
larger than the radial size of the small radial gap L2. That is,
the outer diameter L3 of the roller 7, the radial size of the large
radial gap L1 and the radial size of the small radial gap L2 are
set to satisfy the relationship of L1>L3>L2. In this way, the
roller 7 is always retained in the gap G between the radially outer
surface 13 of the fan-shaped portion 12 of the driven-side rotator
5 and the inner circumferential surface 8 of the collar 6.
[0038] When the roller 7 is placed in a location, at which the
radial distance between the radially outer surface 13 of the
fan-shaped portion 12 and the inner circumferential surface 8 of
the collar 6 is larger than the outer diameter of the roller 7, the
driven-side rotator 5 can rotate relative to the collar 6.
Furthermore, when the roller 7 is placed in another location, at
which the radial distance between the radially outer surface 13 of
the fan-shaped portion 12 and the inner circumferential surface 8
of the collar 6 coincides with the outer diameter L3 of the roller
7, the roller 7 is securely held between the radially outer surface
13 of the fan-shaped portion 12 and the inner circumferential
surface 8 of the collar 6. That is, the driven-side rotator 5 is
locked to the collar 6 through the rollers 7, and thereby the
rotation of the driven-side rotator 5 is prevented by the collar 6,
which is securely held.
[0039] The driving-side rotator 4 is securely engaged or connected
with an output shaft (an input side of the clutch 3) of the motor 1
to rotate integrally therewith and has a plurality (three in this
embodiment) of fan-shaped portions 16. In this way, when the
driving-side rotator 4 is rotated by the motor 1, the fan-shaped
portions 16 of the driving-side rotator 4 abut against the
fan-shaped portions 12, respectively, of the driven-side rotator 5
in the circumferential direction to conduct the rotational force of
the driving-side rotator 4 to the driven-side rotator 5.
[0040] Two engagement releasing projections 17 project
circumferentially outward from two opposed circumferential ends,
respectively, of each fan-shaped portion 16 of the driving-side
rotator 4. In a state where each fan-shaped portion 16 of the
driving-side rotator 4 abuts against the corresponding fan-shaped
portion 12 of the driven-side rotator 5, the engagement releasing
projection 17 pushes the corresponding holder 14 toward the large
radial gap L1 to displace the corresponding roller 7, which is
supported by the holder 14, toward the large radial gap L1.
Specifically, the roller 7 is moved to the location where the
radial distance between the radially outer surface 13 of the
fan-shaped portion 12 of the driven-side rotator 5 and the inner
circumferential surface 8 of the collar 6 is larger than the outer
diameter L3 of the roller 7 to enable rotation of the roller 7
between the fan-shaped portion 12 of the driven-side rotator 5 and
the collar 6.
[0041] The speed reducer 2 is a speed reducer of a gear type and
will be described with reference to FIGS. 3A and 3B. The speed
reducer 2 of the present embodiment includes a worm 21, an
intermediate gear 22 and a final gear 23. The worm 21 is rotated
integrally with the driven-side rotator 5. The intermediate gear 22
is meshed with the worm 21 and is driven by the worm 21. The final
gear 23 is meshed with the intermediate gear 22 and is driven by
the intermediate gear 22. The output shaft 24, which is provided in
the final gear 23, is connected to the valve drive shaft 100b to
drive the same.
[0042] Now, a basic operation of the clutch 3 will be
described.
[0043] When the motor 1 is rotated in the forward direction or the
reverse direction through the control operation of the energization
of the motor 1, the rotational force of the motor 1 conducted to
the driving-side rotator 4 causes the corresponding one of the
engagement releasing projections 17 of each fan-shaped portion 16
of the driving-side rotator 4 to push the corresponding roller 7
through the corresponding holder 14 toward the corresponding large
radial gap L1. In this way, the driving-side rotator 4 and the
driven-side rotator 5 together with the collars 7 are permitted to
rotate freely relative to the collar 6. Then, when the rotational
force of the driving-side rotator 4 is conducted to the driven-side
rotator 5 upon abutment of the driving-side rotator 4 to the
driven-side rotator 5, the driven-side rotator 5 is rotated
together with the driving-side rotator 4. The rotational speed of
the driven-side rotator 5 is reduced through the speed reducer 2,
and the rotation of the speed reducer 2 at the reduced rotational
speed is outputted through the output shaft 24 to change the
opening degree of the valve 100.
[0044] When the opening degree (the rotational angular position) of
the valve 100 reaches the target opening degree (the target
rotational angular position) of the valve 100, the energization of
the motor 1 is stopped (i.e., the motor 1 in a de-energized state).
In this state, for example, when a rotational load is manually
applied to the valve 100 to apply a rotational force to the
driven-side rotator 5, each roller 7 is clamped, i.e., is securely
held between the driven-side rotator 5 and the collar 6 upon a
slight rotational movement of the driven-side rotator 5. Thus, the
driven-side rotator 5 is securely locked to the collar 6 through
the rollers 7. Therefore, the driven-side rotator 5 becomes
non-rotatable, and thereby the rotation of the valve 100 is
limited.
[0045] However, the pressure pulsation, which occurs in the intake
passage, causes application of a rotational force (specifically, a
rotational force caused by large vibration, large load, large
pressure pulsation or the like) to the valve 100. Particularly, in
the case of the present example, in which the hinged valve
structure is adapted, a very large pressure pulsation is applied to
the valve drive shaft 100b. Then, the rotational force, which is
caused by this pressure pulsation, is conducted to the driven-side
rotator 5 through the speed reducer 2, so that the locked state of
each roller 7 may possibly be released. That is, the rotation of
the valve 100 may not be effectively limited by the clutch 3.
[0046] In view of the above point, the following technique is
adapted in the present embodiment to increase the holding
capability of the clutch 3 for holding the valve 100 in place (in
the selected angular position).
[0047] Specifically, the inner circumferential surface 8 of the
collar 6 of the clutch 3 has a plurality of recesses, each of which
is capable of limiting the movement and rotation of the
corresponding one of the rollers 7 in the urged state of the roller
7.
[0048] The recesses of the present embodiment are formed as grooves
25, into each of which the corresponding roller 7 can be lightly
fitted (engaged). Each groove 25 extends parallel to the axis of
the roller 7. As shown in FIG. 2B, a cross section of each groove
25 may have an arcuate shape that forms an arcuate surface having a
curvature (or a radius of curvature), which may generally coincide
with or may be larger (substantially or slightly larger) than or
smaller (substantially or slightly smaller) than that of the
cylindrical outer surface (circular cross section) of the roller 7.
Furthermore, the cross section of the groove may have any other
shape, which is other than the arcuate shape. For example, the
cross section of the groove may be configured into a rectangular
shape, a triangular shape (including moderately tilted surfaces) or
the like.
[0049] The number of the grooves 25 is, for example, nine in this
instance and may be increased or decreased depending on a need. The
grooves 25 are arranged one after another at generally equal
angular intervals along the inner circumferential surface 8 of the
collar 6.
[0050] As described above, the grooves 25 are provided in the inner
circumferential surface 8 of the collar 6, so that each roller 7
can be fitted (engaged) into the corresponding groove 25 in the
de-energized state of the motor 1. As a result, the roller 7 can be
strongly locked (engaged) to the collar 6 through the groove 25 in
the de-energized state of the motor 1, and thereby the rotation of
the driven-side rotator 5 cab be limited without fully relying on
the frictional force between the roller 7 and the collar 6.
Therefore, the change in the opening degree (the change in the
rotational position) of the valve 100 caused by the pressure
pulsation can be advantageously limited.
[0051] At the time of driving the motor 1 to rotate the
driving-side rotator 4 in the forward direction or the reverse
direction, the corresponding engagement releasing projection 17 of
each fan-shaped portion 16 of the driving-side rotator 4
circumferentially pushes the corresponding roller 7 toward the
large radial gap L1 to release the locking of the roller 7. Then,
when the driving-side rotator 4 circumferentially abuts against the
driven-side rotator 5 to conduct the rotational force of the
driving-side rotator 4 to the driven-side rotator 5, the opening
degree (the rotational position) of the valve 100 is adjusted,
i.e., is changed.
[0052] The variable air intake system is required to set the
opening degree of the valve 100 within an effective opening degree
range thereof, which enables an improvement of the fuel consumption
of the engine.
[0053] (a) Specifically, when the opening degree of the valve 100
is reduced, the pumping loss is increased to cause the
deterioration of the fuel consumption (see FIG. 4).
[0054] (b) In contrast, when the opening degree of the valve 100 is
reduced to cause generation of the swirl flow in the combustion
chamber, the fuel combustion state is improved to improve the
internal (external) limit exhaust gas recirculation (EGR) ratio.
That is, when the EGR ratio at the time of operating the engine
with the small opening degree of the valve 100 is increased, the
cooling loss and the pumping loss are reduced to obtain the fuel
consumption improving effect (see FIG. 5).
[0055] Because of the relationship between the item (a) and the
item (b) discussed above, there exists a predetermined effective
opening degree range of the valve 100 for obtaining the fuel
consumption improving effect (see FIG. 6). That is, when the valve
100 is driven out of the predetermined opening degree range toward
the fully closed position thereof, the effect of the fuel
consumption deteriorating rate caused by the pumping loss becomes
larger than the fuel consumption improvement caused by the EGR.
Thereby, as a whole, the fuel consumption is deteriorated. In
contrast, when the valve 100 is driven to increase the opening
degree of the valve 100 beyond the predetermined opening degree
range, the fuel consumption improving effect of the EGR cannot be
obtained, so that the fuel consumption is deteriorated as a
whole.
[0056] As described above, there exists the effective opening
degree range of the valve 100, within which the fuel consumption of
the engine can be improved. In the variable air intake system, it
is required to set the opening degree of the valve 100 within this
effective opening degree range of the valve 100, which enables the
improvement of the fuel consumption.
[0057] In order to maintain the opening degree of the valve 100
within the effective opening degree range of the valve 100, the
circumferential locations of the grooves 25 are set as follows. In
the following description, only one of the rollers 7 of the clutch
3 and its associated grooves 25 will be described with reference to
the valve 100 for the sake of simplicity.
[0058] The clutch 3 and the valve 100 are synchronized to satisfy
the following conditions. That is, with reference to FIG. 1, when
the driving-side rotator 4 is rotated to rotate the driven-side
rotator 5 and thereby to place the roller (more specifically, a
circumferential center or a location adjacent thereto of the
roller) 7 in an optimum angular position (first angular position) Z
along the circumferential surface 8 of the collar 6, the valve 100
is placed in a most effective valve angle .theta., at which the
fuel consumption improving effect (the fuel consumption improving
rate) of the intake air supplied from the valve 100 to the engine
through the air intake passage 111 is maximized. When the
driving-side rotator 4 is rotated to rotate the driven-side rotator
5 and thereby to displace the roller (more specifically, the
circumferential center or the location adjacent thereto of the
roller) 7 in one circumferential direction from the optimum angular
position Z to a valve closing side least effective angular position
(second angular position) e1 along the circumferential surface 8 of
the collar 6, the valve 100 is rotated in a valve closing direction
from the most effective valve angle .theta. to a valve closing side
least effective valve angle f1, at which the fuel consumption
improving effect of the intake air supplied from the valve 100 to
the engine through the air intake passage 111 is reduced to zero.
When the driving-side rotator 4 is rotated to rotate the
driven-side rotator 5 and thereby to displace the roller (more
specifically, the circumferential center or the location adjacent
thereto of the roller) 7 in an opposite circumferential direction,
which is opposite from the one circumferential direction, from the
optimum angular position Z to a valve opening side least effective
angular position (third angular position) e2 along the
circumferential surface 8 of the collar 6, the valve 100 is rotated
in a valve opening direction from the most effective valve angle
.theta. to a valve opening side least effective valve angle f2, at
which the fuel consumption improving effect of the intake air
supplied from the valve 100 to the engine through the air intake
passage 111 is reduced to zero.
[0059] One (serving as a valve closing side engaging recess or
groove) of the grooves 25 is formed at a corresponding angular
position x, more specifically a circumferential center or a
location adjacent thereto of the valve closing side engaging groove
25 is placed at the corresponding angular position x in the
circumferential surface 8 of the collar 6 between the optimum
angular position Z and the valve closing side least effective
angular position e1 and is engageable with the roller 7 to securely
hold the roller 7 in cooperation with the fan-shaped portion 12 of
the driven-side rotator 5 in the de-energized state of the electric
motor upon application of the rotational force from the valve 100
to the driven-side rotator 5. Another one (serving as a valve
opening side engaging recess or groove) of the grooves 25 is formed
at a corresponding angular position y, more specifically a
circumferential center or a location adjacent thereto of the valve
opening side engaging groove 25 is placed at the corresponding
angular position y in the circumferential surface 8 of the collar 6
between the optimum angular position Z and the valve opening side
least effective angular position e2 and is engageable with the
roller 7 to securely hold the roller 7 in cooperation with the
fan-shaped portion 12 of the driven-side rotator 5 in the
de-energized state of the motor 1 upon application of the
rotational force from the valve 100 to the driven-side rotator 5.
In addition, another one (serving as an optimal position engaging
recess or groove) of the grooves 25 is formed at the optimal
angular position Z, more specifically, the circumferential center
or the location adjacent thereto of the optimal position engaging
groove 25 is placed at the optimum angular position Z in the
circumferential surface 8 of the collar 6 to securely hold the
roller 7 in cooperation with the fan-shaped portion 12 of the
driven-side rotator 5 in the de-energized state of the motor 1 upon
application of the rotational force from the valve 100 to the
driven-side rotator 5.
[0060] Here, although only one valve closing side engaging groove
25 is formed in the circumferential surface 8 of the collar 6
between the optimum angular position Z and the valve closing side
least effective angular position e1, and only one valve opening
side engaging groove 25 is formed in the circumferential surface 8
of the collar 6 between the optimum angular position Z and the
valve opening side least effective angular position e2. However, it
is possible to provide more than one valve closing side engaging
groove 25 between the optimum angular position Z and the valve
closing side least effective angular position e1 and more than one
valve opening side engaging groove 25 between the optimum angular
position Z and the valve opening side least effective angular
position e2.
[0061] Furthermore, a speed reduction ratio G of the speed reducer
2 satisfies relationships of .gamma.1/G.ltoreq..alpha. and
.gamma.2/G.ltoreq..beta. to implement the above locations of the
valve closing side engaging groove 25 and of the valve opening side
engaging groove 25. Here, the speed reduction ratio G is a ratio
between the rotational speed of the input side (the input shaft 11)
of the speed reducer 2 and the rotational speed of the output side
(the output shaft 24) of the speed reducer 2. In other words, the
speed reduction ratio G indicates the number of rotations of the
input side (the input shaft 11) of the speed reducer 2 per rotation
of the output side (the output shaft 24) of the speed reducer 2.
Here, .gamma.1 denotes an angular difference between the optimum
angular position Z and the angular position x of the valve closing
side engaging groove 25 along the circumferential surface 8 of the
collar 6, and a denotes an angular difference between the most
effective valve angle .theta. and the valve closing side least
effective valve angle f1. Also, .gamma.2 denotes an angular
difference between the optimum angular position Z and the angular
position y of the valve opening side engaging groove 25 along the
circumferential surface 8 of the collar 6, and 3 denotes an angular
difference between the most effective valve angle .theta. and the
valve opening side least effective valve angle f2. In this
instance, since the angular difference .gamma.1 and the angular
difference .gamma.2 are the same (.gamma.), the above relationships
may be expressed as .gamma./G.ltoreq..alpha. and
.gamma./G.ltoreq..beta.. Through use of the above relationships, it
is easy to set the above locations of the valve closing side
engaging groove 25 and of the valve opening side engaging groove 25
within the range of the angular difference .gamma.1 and the angular
difference .gamma.2, respectively, without knowing the location of
the valve closing side least effective angular position e1 or the
location of the valve opening side least effective angular position
e2 even in the case where the most effective valve angle .theta.
varies from one model to another model as long as the speed
reduction ratio G and the angular difference .alpha., .beta. are
known.
[0062] The above embodiment provides the following advantages.
[0063] With the above construction of the variable air intake
system, at least one valve closing side engaging groove 25 is
formed in the circumferential surface 8 of the collar 6 between the
optimum angular position Z and the valve closing side least
effective angular position e1, and at least one valve opening side
engaging groove 25 is formed in the circumferential surface 8 of
the collar 6 between the optimum angular position Z and the valve
opening side least effective angular position e2. Therefore, it is
possible to reliably hold the valve 100 within the effective
opening degree range (the range between the valve closing side
least effective valve angle f1 and the valve opening side least
effective valve angle f2) of the valve 100, which enables the
improvement of the fuel consumption of the engine.
[0064] That is, even when the large vibration, the large load
and/or the large pressure pulsation applied to the valve 100 is
conducted to the driven-side rotator 5 through the speed reducer 2,
the roller 7 can be securely engaged in the corresponding groove 25
located between the valve closing side least effective angular
position e1 and the valve opening side least effective angular
position e2, so that the roller 7 can be more securely held between
the groove 25 of the collar 6 and the fan-shaped portion 12 of the
driven-side rotator 5 to limit the displacement of the roller 7 to
fix the opening degree of the valve 100 within the effective
opening degree range.
[0065] In the above embodiment, the speed reducer 2 is placed only
between the clutch 3 and the valve 100. Alternatively, an
additional speed reducer may be placed between the motor 1 and the
clutch 3 besides the above speed reducer 2.
[0066] The number of the recesses (e.g., the grooves 25 or the
tilts) is set such that the two grooves are provided at the
corresponding locations on the valve closing side and the valve
opening side, respectively, of the optimum angular position Z to
achieve the conditions of .gamma.1/G.ltoreq..alpha. and
.gamma.2/G.ltoreq..beta.. However, the number of the recesses (e
g., the grooves 25, the tilts) may be further increased from the
above number. That is, the recesses (e.g., the grooves 25 or the
tilts) may be provided one after another at the equal angular
intervals of the angle .gamma. in a manner that satisfies
conditions of .gamma./G.ltoreq..alpha. and
.gamma./G.ltoreq..beta..
[0067] In the above embodiment, the hinged valve 100 is used. In
place of the hinged valve, a butterfly valve (e.g., a butterfly
valve, which has a circular valve plate and a valve drive shaft
extending through a center of the circular valve plate in a
direction parallel to a plane of the circular valve plate) may be
used. Also, the valve of the present invention may be used as any
other types of valves (e.g., a throttle valve), if desired.
[0068] In the above embodiment, the radially outer surface 13 of
each fan-shaped portion 12 is the planar surface. Alternatively, an
engaging groove, which has an arcuate cross section and extends in
the axial direction of the driven-side rotator 5, may be formed in
the radially outer surface 13 of each fan-shaped portion 12 in such
a manner that the engaging groove of the radially outer surface 13
is engageable with the corresponding roller 7.
[0069] In the above embodiment, each roller 7 is held by the
corresponding holder 14. Alternatively, the holder 14 may be
eliminated.
[0070] In the above embodiment, the cylindrical roller 7 is used as
the example of the engageable element. Alternative to the roller 7,
any other type of rotatable or rollable element (e.g., a spherical
ball) may be used as the engageable element. The outer shape of the
rotatable element is not necessarily circular. For instance, the
outer shape of the rotatable element may be ellipsoidal or the
like, which resists smooth rotation thereof. Furthermore, the
engageable element is not necessarily the rotatable element. For
example, the engageable element may be a slidable element, which is
slidable between the driven-side rotator 5 and the collar 6.
[0071] In the above embodiment, the collar 6 is placed radially
outward of the driving-side rotator 4 and the driven-side rotator
5. Alternatively, the collar 6 may be placed radially inward of the
driving-side rotator 4 and the driven-side rotator 5. In such a
case, the outer circumferential surface of the collar 6 serves as
the circumferential surface that is engageable with the engageable
elements (e.g., the rollers 7). Thus, the recesses (e.g., the
grooves 25 or the tilts) may be provided in the outer
circumferential surface of the collar 6.
[0072] In the above embodiment, the driving-side rotator 4 and the
driven-side rotator 5 make the surface contact therebetween.
Alternatively, the driving-side rotator 4 and the driven-side
rotator 5 may make a point contact, a line contact or the like
therebetween.
[0073] Additional advantages and modifications will readily occur
to those skilled in the art. The invention in its broader terms is
therefore not limited to the specific details, representative
apparatus, and illustrative examples shown and described.
* * * * *