Title: Throttle device for internal-combustion engine
Abstract: Disclosed is a throttle device for an internal-combustion engine, in which, on one side of the side wall of a throttle body, there are formed a space for mounting a reduction gear mechanism which transmits the power from a motor to a throttle valve shaft and a default opening setting mechanism for holding a throttle valve opening at a specific opening (default opening) when the ignition switch is in off position, and a gear cover mounting frame which edges the mounting space. The frame is formed lower than the mounting level of the reduction gear mechanism. A gear cover for covering the gear mounting space is attached on the frame. A stopper for defining the default opening and a stopper for defining the full-closed position of the throttle valve are juxtaposed so as to enable position adjustments in the same direction. These stoppers serve to stop a default lever and a throttle gear, thereby enabling downsizing, weight reduction, and rationalization of fabrication and adjustments of an electronically controlled throttle device.
Patent Number: 6,945,228 Issued on 09/20/2005 to Saito, et al.
| Inventors:
|
Saito; Yasuo (Hitachinaka, JP);
Hashimoto; Yoshikatsu (Hitachiota, JP);
Wayama; Eisuke (Hitachinaka, JP);
Usui; Toshifumi (Hitachinaka, JP)
|
| Assignee:
|
Hitachi, Ltd. (Tokyo, JP);
Hitachi Car Engineering Co., Ltd. (Hitachinaka, JP)
|
| Appl. No.:
|
461453 |
| Filed:
|
June 16, 2003 |
| Current U.S. Class: |
123/399; 123/361 |
| Intern'l Class: |
F02D 009/10 |
| Field of Search: |
123/361,399
|
References Cited [Referenced By]
U.S. Patent Documents
| 4735179 | Apr., 1988 | Ejira et al.
| |
| 4947815 | Aug., 1990 | Peter.
| |
| 6039027 | Mar., 2000 | Sato et al.
| |
| 6080075 | Jun., 2000 | Wussow et al.
| |
| 6279535 | Aug., 2001 | Matsusaka.
| |
| 6502542 | Jan., 2003 | Stuart.
| |
| 6598587 | Jul., 2003 | Kamimura et al.
| |
| 2001/0032616 | Oct., 2001 | Sakuria et al.
| |
| 2001/0045202 | Nov., 2001 | Shimura et al.
| |
| 2001/0045203 | Nov., 2001 | Arsic et al.
| |
| 2002/0040974 | Apr., 2002 | Kamimura et al.
| |
| Foreign Patent Documents |
| 62-82238 | Apr., 1987 | JP.
| |
| 63-150449 | Jun., 1988 | JP.
| |
| 1-085432 | Jun., 1989 | JP.
| |
| 09-032588 | Feb., 1997 | JP.
| |
| 09-303164 | Nov., 1997 | JP.
| |
| 10-089096 | Apr., 1998 | JP.
| |
| 10-131771 | May., 1998 | JP.
| |
| 11-190232 | Jul., 1999 | JP.
| |
Primary Examiner: Solis; Erick
Attorney, Agent or Firm: Crowell & Moring LLP
Parent Case Text
This application is a continuation of application Ser. No. 10/298,579, filed
Nov. 19, 2002 now U.S. Pat. No. 6,591,807 which is a continuation of application
Ser. No. 10/141,120, filed May 9, 2002 and issued as U.S. Pat. No. 6,488,010; which
is a continuation of application Ser. No. 09/462,864, filed Jan. 18, 2000 and issued
as U.S. Pat. No. 6,390,062; which is a 371 of PCT/JP99/02400 filed on May 10, 1999.
Claims
1. A motor-driven type intake air amount control apparatus having a throttle
valve which is driven by a motor to control the amount of intake air of an internal-combustion
engine, comprising:
a throttle body equipped with said throttle valve and said motor;
a synthetic resin cover attached to the contact surface of said throttle body,
and said cover having terminals for connecting electrically with terminals of said
motor;
wherein said motor is fixed to said throttle body by screwing a motor bracket
to the side wall of said throttle body,
said motor terminals protrude from said motor bracket to connect with the terminals
of said cover,
said contact surface of said throttle body is located between said side wall
of said throttle body and an end of a shaft of said motor,
each end of said motor terminals protrudes beyond said contact surface of said
throttle body,
said motor shaft is equipped with a pinion gear, said pinion gear meshes with
a large-diameter gear section of an intermediate gear at a place protruding beyond
said contact surface of said throttle body,
a small-diameter gear section of said intermediate gearmeshes with a gear fixed
on a throttle shaft having said throttle valve, and a reduction gear mechanism,
comprised of said intermediate gear, said pinion gear and said gear fixed on said
throttle shaft, is located in a space between said cover and said throttle body.
2. A motor-driven type intake air amount control apparatus according to claim
1, wherein plugged-in type joints used for terminal-connection are located between
said motor terminals and the terminals of said cover.
3. A motor-driven type intake air amount control apparatus according to claim
1, wherein a connector for connecting with an external electronic unit is provided
to said cover;
said motor terminals are connected with the terminals of said connector through
conductors;
said cover is equipped with a sensor for detecting the angle of rotation of said
throttle value;
said sensor is connected with the terminals of said connector through conductors
embedded in said cover;
and the conductors between said motor terminals and said connector are shorter
than the conductors between said sensor and said connector.
4. A motor-driven type intake air amount control apparatus according to claim
1, wherein said small-diameter gear section of said intermediate geara nd said
gear on said throttle shaft mesh together at a place which is a throttle body side
from the meshing position of said large-diameter gear section of said intermediate
gear and said motor pinion gear.
5. A motor-driven type intake air amount control apparatus according to claim
1, wherein said gear on said throttle shaft is provided with a stopper element
which is received by a full-closed stopper at a full-closed position of said throttle
valve, and said full-closed stopper protrudes beyond said contact surface of said
throttle body.
6. A motor driven type intake air amount control apparatus according to claim
5, said apparatus further comprising a default opening setting mechanism which
functions to keep said throttle valve a default opening as a specific initial opening
wider than the full-closed position when said motor is off,
a default stopper for setting the default opening is located closer to a bearing
said throttle shaft than said full-closed stopper.
7. A motor-driven type intake air amount control apparatus according to claim
6, wherein said gear on said throttle shaft is provided with a portion to which
an end of a spring as a member of said default opening setting mechanism is hooked
in the rotating direction of said gear.
8. A motor-driven type intake air amount control apparatus according to claim
6, further said apparatus comprising a throttle sensor for detecting the amount
of opening of the throttle valve, wherein the components of said throttle sensor
are provided at an end of the throttle shaft and on the inner surface of said cover.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a throttle device for an internal-combustion engine
and, more particularly, to an electronically controlled throttle device which controls
the opening and closing operation of a throttle valve by driving an electric actuator
according to a control signal.
2. Description of Related Art
In an electronically controlled throttle device which controls an engine throttle
valve by driving an electric actuator (e.g., a D C motor and a stepping motor),
there has been known such a technology that the amount of initial opening (default
opening) of the throttle valve is set larger than a full-closed position when an
ignition switch is in off position (in other words, when no current is being supplied
to the electric actuator).
Here, the full-closed position of the throttle valve is not meant by a position
in which the intake air passage is full-closed; especially in a throttle device
having no bypass around the throttle valve and controlling the idling speed only
by means of the throttle valve, the full-closed position is defined as a mechanically
full-closed position and an electrically full-closed position which will be described below.
The mechanically full-closed position is the minimum opening position of the
throttle valve defined by a stopper. The minimum opening is set at a position where
the intake air passage is slightly opened from a full-closed position to thereby
prevent the throttle valve from galling. The electrically full-closed position
is the minimum opening position within the range of opening used in engine control,
and is set, by the control of the electric actuator, at a position of a slightly
wider opening than the mechanically full-closed position (e.g., about 1 deg. larger
than the mechanically full-closed position).
In the electronically controlled throttle, the electrically full-closed position
(the minimum opening for control) and the idle opening (an opening required for
controlling the idle speed) do not necessarily agree. This is because the amount
of opening of the throttle valve is controlled by a feed-back control system according
to an idle speed detection signal in order to keep a target idle speed, and for
this purpose the amount of opening is allowed to vary.
The full-open position has also a mechanically full-open position defined by
the stopper and an electrically full-open position in which the throttle valve
is opened to the maximum control amount of opening. The full-closed position stated
herein includes the mechanically full-closed position and the electrically full-closed
position as well. In normal control, the throttle valve is controlled within the
range from the electrically full-closed position (the minimum opening for control)
to the electrically full-open position (the maximum opening for control), so that
a part of the throttle valve shaft will not hit on the stopper which determines
the mechanically full-closed and full-open positions, when the throttle valve is
being controlled to the minimum or maximum opening. Thus it becomes possible to
protect the stopper and throttle components from mechanical fatigue, abrasion,
and damage, and also to prevent galling to the stopper.
The default opening (i.e., the initial opening when the ignition switch is in
off position) is set to the amount of opening of the throttle valve which is opened
wider than the full-closed position (the mechanically full-closed position and
the electrically full-closed position) (e.g., 4 to 13 deg. wider than the mechanically
full-closed position).
The default opening is set from the reason for achieving the air flow rate necessary
for fuel combustion for operation to be performed prior to engine warm-up at the
time of engine starting (cold starting) without providing an auxiliary air passage
(an air passage bypassing the throttle valve). During idling, the throttle valve
is controlled towards decreasing the amount of opening from the default opening
as the engine warm-up proceeds (in this case, however, the electrically full-closed
position is the lower limit position).
Furthermore, the default opening is adopted to meet requirements for
insuring self-running (limping home) in the event of a throttle control system
trouble or insuring an intake air flow rate necessary for preventing an engine
stop, and for preventing the throttle valve from being stuck with a viscous substance,
ice, or other, on the inside wall of the throttle body.
As a conventional example of a default opening setting mechanism, various mechanisms
have been proposed. A known prior art has been stated in, for example, Japanese
Laid-Open No. Sho 63-150449 Patent Publication, U.S. Pat. No. 4,947,815 specification
, Japanese Translation of PCT Application No. Hei 2-500677 corresponding to the
U.S. patent, Japanese Laid Open No. Sho 62-82238 Patent Publication and its corresponding
U.S. Pat. No. 4,735,179 specification, Japanese Laid-Open No. Hei 10-89096 Patent
Publication, and Japanese Laid Open No. Hei 10-131771 Patent Publication.
There are various types of default opening setting mechanisms, a typical type
of which for example is as follows.
One type is of such a system that a default opening setting engagement element
(a default lever) which is fitted on the throttle valve to enable the rotation
of the engagement element on the throttle valve shaft is engaged via a spring with
an element secured on the throttle valve, thereby allowing the default lever to
turn together with the throttle valve shaft between the range from the default
opening position to the valve full-open position. When the ignition switch is in
off position, the default lever is held in contact with the default stopper, to
thereby hold the throttle valve opening at the default opening. To close the throttle
valve to the default opening or less, the default lever is disengaged from the
throttle valve shaft to allow the throttle valve shaft to rotate independently
against a spring force towards closing the throttle valve.
Another type is of such a system that, reversely to the above-described system,
the default lever and the throttle valve shaft are turned together from the throttle
valve full-close position to the default opening position. When the ignition switch
is off, the default lever is held in contact with the default stopper to hold the
throttle valve opening at the default opening. When the throttle valve is opened
over the throttle opening, the default lever is disengaged from the throttle valve
shaft, to allow the throttle valve shaft to turn towards opening independently
against the spring force.
The electronically controlled throttle device can perform more accurately the
air flow rate control suitable for the operation of the internal-combustion engine
than a mechanical throttle device which transmits the amount of depression of the
accelerator pedal to the throttle valve shaft through an accelerator cable. The
component count is increased to provide an electric actuator, a default opening
setting mechanism, and a throttle sensor. Therefore, downsizing, weight reduction
and simplification, rationalization of fabrication and adjustment jobs, and further
improvement in operation stability and accuracy of the throttle body, are demanded.
SUMMARY OF THE INVENTION
To solve the above-described problem, therefore, it is an object of the invention
to realize the downsizing, weight reduction and simplification of the throttle
body equipped with an electric actuator, a gear mechanism and a default opening
setting mechanism, the rationalization of fabrication and adjustment jobs, and
further improvement in operation stability and accuracy.
This invention basically has the following constitution.
The first aspect of the invention pertains to the throttle device for an internal-combustion
engine which is driven by an electric actuator to open and close the throttle valve
to thereby control the amount of intake air aspirated by the internal-combustion
engine. In the throttle device, there are formed, on one surface of the side wall
of the throttle body, a reduction gear mechanism mounting space which transmits
to the throttle valve shaft the power of the electric actuator, and a frame for
mounting a gear cover formed to define the space for mounting the reduction gear
mechanism. The frame is built lower than the mounting height of the gear mounted
on one end of the throttle valve shaft. On the frame is attached the gear cover
for covering reduction gear mechanism mounting space.
According to the above-described constitution, the reduction gear mechanism
mounting space is covered with a gear cover, which covers most of the mounting
space, in place of a gearcase and a gear cover mounted on the side wall of a conventional
throttle body. In this sense, the gear cover plays a role of the gearcase. Unlike
the conventional type, therefore, the throttle body itself is not needed to be
formed integrally with a gearcase having a relatively large volume. A gear cover
made of a synthetic resin should be increased in the volume; generally, therefore,
it is possible to reduce the size and weight of the metal throttle body formed
by mold casting.
The second aspect of the invention pertains to the throttle device of the internal-combustion
engine having the default opening setting mechanism to hold the amount of opening
of the throttle valve at a specific opening (the default opening) which is larger
than the full-close position when the electric actuator is off.
In this throttle device, the stopper for defining the default opening position
and the stopper for defining the mechanically full-closed position of the throttle
valve are comprised of adjusting screws. These stoppers are so juxtaposed as to
enable adjustment of their position in the same direction.
According to the above-described constitution, it is possible to freely
adjust the default opening and the mechanical full-closed position of the throttle
valve. Besides, since the adjusting screw of the default opening stopper (the default
stopper) and the adjusting screw of the full-closed stopper are juxtaposed to allow
position adjustment from the same direction, it is possible to drill screw holes
for these stoppers (screws)in the same direction, and moreover to perform the adjustment
of the stopper positions in close positions from the same direction, thereby enabling
simplification of adjustment jobs.
The third aspect of the invention is application of the first and second aspects
of the invention, pertaining to the throttle device of the internal-combustion
engine. In the aspect, the full-closed stopper stops the reduction gear (the final
gear) fixedly attached on the throttle valve shaft, to thereby define the mechanical
full-closed position, while the default stopper stops an engagement element for
setting the default opening (this engagement element is a default lever freely
fitted on the throttle valve shaft to enable rotation of the shaft and engaged
with the final gear through a spring), thus defining the default opening.
In the throttle device, there are formed, on one surface of the side wall of
the
throttle body, a space for mounting a reduction gear mechanism which transmits
to the throttle valve shaft the power of the electric actuator, and a frame for
mounting a gear cover formed to define the space for mounting the reduction gear.
The frame is built lower than the mounting height of the final gear. In the position
covered by the gear cover, there is provided a projecting portion, which is higher
than the frame, for mounting the full-closed stopper. Mounted on this projecting
portion is the full-closed stopper, at the same mounting height as the final gear
of the reduction gear. On the other hand, the default stopper is juxtaposed with
the full-closed stopper at the position of the said engagement element (the default
lever) which is located at the lower level than the said frame.
According to the above-described constitution, the space for mounting the
reduction gear mechanism is covered almost by the gear cover like in the first
aspect of the invention. It is, therefore, possible to reduce the size and weight
of the metal throttle body.
The final gear of the reduction gear protrudes out of the gear cover mounting
frame on the throttle body side wall; therefore, the final gear can not be stopped
if the full-closed stopper is provided on this frame. In the aspect, there is provided
a projecting portion for mounting the full-closed stopper which stops the final
gear. The projecting portion protrudes high over the frame. On this projecting
portion the full-closed stopper is arranged at the same mounting height as the
final gear.
According to this arrangement, it is possible to stop the final gear by
the full-closed stopper if the gear cover mounting frame is built low.
The fourth aspect of the invention pertains to a throttle device for an internal-combustion
engine having the default opening setting mechanism.
The throttle valve shaft protrudes out at one end from the bearing boss formed
on the throttle body side wall, and the final gear of the reduction gear for transmitting
the power of the electric actuator is fixedly attached on the one end of the throttle
valve shaft. Between the final gear and the bearing boss, the engagement element
(the default lever) of the default opening setting mechanism capable of engaging
with the final gear is rotatable with respect to the throttle valve shaft.
A return spring is arranged around the bearing boss for exerting the spring force
to the throttle valve in the direction the throttle valve is closed. The return
spring engages at one end with the default lever; and between the default lever
and the final gear there is mounted a spring (the default spring) for attracting
the default lever and the final gear towards mutual engagement.
A throttle valve shaft insertion boss is formed only on the surface side (one
surface
side) of the final gear which receives the default spring. The default lever also
has a throttle valve shaft insertion boss formed correspondingly to the final gear
boss. And a round these bosses the default spring is mounted.
According to the above-described constitution, the return spring and the
default spring can be installed in a free space inevitably formed around each boss.
That is, rational utilization of space is realized. Moreover, since the boss of
the final gear of the reduction gear is protrusively formed on one side only, the
amount of projection of the boss (the length of boss axis) protruding out from
one side of the final gear can be made longer than the amount of projection of
the boss on one side of double-sided bosses (bosses protruded on both sides of
the final gear). Therefore, it becomes possible to provide the default opening
setting mechanism with a spring mounting space without wasted space while realizing
a downsized throttle device.
The fifth aspect of the invention pertains to a throttle device for an internal-combustion
engine having the default opening setting mechanism.
In the throttle device, the final gear of the reduction gear which transmits
the
power of the electric actuator is secured on one end of the throttle valve shaft,
and the engagement element (the default lever) of the default opening setting mechanism
is relatively rotatably fitted on the throttle valve shaft.
Between the default lever and the final gear there is installed a spring
(a default spring) for setting the default opening which pulls the default lever
and the final gear towards mutual engagement. The default spring is characterized
by the spring stop mechanism that the default spring is supported by the default
lever and the final gear.
According to the above-described constitution, the default lever and the
final gear of the reduction gear serve also as a default spring bracket, thereby
enabling simplification of component parts.
It is, therefore, proposed as an example of application that at least a portion
forming the boss and a portion receiving the default spring of the default lever
are made of a synthetic resin.
According to the above-described constitution, since the synthetic resin
is of a less coefficient of friction than a metal member, friction between the
default spring and a member (the spring stop portion in the default lever, and
the boss portion) which contacts the default spring will be decreased to reduce
a burden on the motor if the default spring is twisted by the relative rotation
of the default lever and the final gear, thereby achieving smooth movement of the
throttle valve driven by the motor and a decreased motor power consumption during operation.
Furthermore, the use of the return spring and the default spring coated
for reducing a coefficient of friction can further decrease its friction with its
mating member in case of distortion of the spring.
The sixth aspect of the invention pertains to a throttle device for an internal-combustion
engine having the default opening setting mechanism.
In the throttle device, the engagement element (the default lever) for setting
the default opening is fitted on one end of the throttle valve shaft in such a
manner that the engagement element can rotate in relation to the throttle valve shaft.
On both sides of the engagement element, the return spring exerting a spring
force
to turn the throttle valve towards closing and the default opening setting spring
(the default spring) exerting the spring force from the full-close position of
the throttle valve to the default opening side are oppositely arranged in the direction
of the throttle valve shaft. These springs which are torsion coil springs seat
on both sides of the engagement element serve as spring stopper, thereby retaining
these springs at one end. These springs differ in coil diameter and are axially
compressed when installed. Furthermore, the compressive stress F of the spring
of large coil diameter is made greater than the compressive stress f of the spring
of small coil diameter. The compressive stress of the spring stated above is spring
rebound which occurs when the spring is compressed.
The throttle valve shaft is required to be disengaged from the engagement element
for setting the default opening and to turn independently when turned within a
specific range of throttle valve opening (e.g., from the default opening to the
electrically full-closed position, or from the default opening to the electrically
full-open position of the throttle valve), and accordingly the engagement element
for setting the default opening is attached loose-fit on the throttle valve shaft
so that the engagement element can rotate with respect to the throttle valve shaft.
Therefore, there exists a clearance between the outer periphery of the
throttle valve shaft and the engagement element for setting the default opening.
Therefore, the engagement element for setting the default opening will vary (displace)
with vibrations if in an unstable state. If the engagement element for setting
the default opening is held by the compressive force of the coil return spring
and the default spring, and if the compressive stresses of these springs are equal,
and also if these springs get out of balance, the engagement element for setting
the default opening is liable to vibrate, becoming unstable. Consequently, the
default opening will vary, and no smooth operation of the engagement element can
be expected.
In the present invention, to cope with this problem, it is necessary to increase
the compressive stress F of the return spring or the default spring having a large
coil diameter than the compressive stress f of the spring having a small coil diameter.
The compressive force F thus increased can overcome the compressive force f, and
unidirectionally press the engagement element in a stable state in a position close
to the outside diameter, thereby preventing the engagement element for setting
the default opening from displacing to enable to maintain a proper condition and
accordingly preventing above-described trouble.
The seventh aspect of the invention pertains to a throttle device for an internal-combustion
engine, wherein the throttle device is provided with a reduction gear for transmitting
the power of the electric actuator to the throttle valve shaft; the final gear
of the reduction gear is pressed in and fixed on one end side protruding out of
the side wall surface of the throttle body of the throttle valve shaft; and the
final gear thus pressed in and fixed can contact the stopper for defining the mechanical
full-closed position of the throttle valve, by driving the electric actuator.
According to the above-described constitution, since the final gear of
the reduction gear serves also as a defining element on the movable side which
restricts the mechanical full-closed position and also the defining element (the
final gear) is pressed in and fixed on the throttle valve shaft, the reduction
gear position is constantly held in a fixed relation with the throttle valve shaft
even in case of a shock caused by the contact of the reduction gear with the full-closed
stopper Therefore, the throttle valve opening set with reference to the mechanically
full-closed position will not vary, thus doing much towards keeping a control accuracy.
The eighth aspect of the invention pertains to a throttle device for an internal-combustion
engine which is driven by an electric actuator to open and close the throttle valve
to control the amount of intake air being aspirated by the internal-combustion engine.
In the throttle device, the motor used as the electric actuator has a yoke forming
a motor housing. The yoke is provided with two opposite flat surfaces. The motor
casing containing the motor has flat opposite inner surfaces formed to the contour
of the motor housing, and is mounted on the side wall of the throttle body, intersecting
the line orthogonal with the throttle valve shaft. Of the opposite flat inner surfaces
of the motor casing, all or most part of one inner surface makes up the outside
wall surface of the intake air passage downstream of the idle opening position
for throttle valve control (e.g., downstream of the electrically full-closed position
for throttle valve control).
According to the above-described constitution, using the flat motor housing
and accordingly the flat motor casing can contribute to the downsizing of the throttle
body. Besides, since one of the flat inner surfaces of the motor casing makes up
the outside wall surface of the intake air passage downstream of the idle opening
position for throttle valve control, the motor casing is most efficiently cooled
by the adiabatic expansion of the intake air occurring downstream immediately after
passing the throttle valve during an idle turn even if the intake air flow rate
is little like during idle turn. Therefore, The cooling of the motor casing interior
and the heat dissipation of the motor housing can be improved, thereby contributing
to achieving a higher motor cooling effect.
The ninth aspect of the invention pertains to a throttle device for an internal-combustion
engine, in which the motor casing for containing the motor, as previously stated,
has opposite flat inner surfaces formed to the contour of the motor housing, and
is installed on the side wall of the throttle body, intersecting the line orthogonal
with the throttle valve shaft. Of the opposite flat inner surfaces of the motor
casing, one inner surface is formed lower than the surrounding outside wall surface
of the intake passage.
According to the above-described constitution, the motor casing wall adjacent
to the intake passage is decreased in thickness to bring the inner surface of the
motor casing closer to the intake passage side, thereby enabling to efficiently
benefit from the cooling effect of the intake air passing through the intake air passage.
Other objects and advantages of the invention will become apparent upon reading
the detailed description and upon reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view schematically showing the power transmission and
default mechanism of a throttle valve of an electronically controlled throttle
device in one embodiment of this invention;
FIG. 2 is an explanatory view equivalently showing the principle of operation
of the electronically controlled throttle device of FIG. 1;
FIG. 3 is a sectional view of the electronically controlled throttle device
pertaining to the embodiments taken perpendicularly to the axial direction of the
intake passage;
FIG. 4 is a view showing the throttle device taken in the same sectional position
as FIG. 3 with the gear cover fitted with the throttle sensor removed;
FIG. 5 is a sectional view of the throttle device of FIG. 3 taken in the axial
direction of the intake air passage;
FIG. 6 is a perspective view of the throttle device;
FIG. 7 is a perspective view showing the throttle device with the gear cover removed;
FIG. 8 is a perspective view showing the throttle device at the angle of view changed;
FIG. 9 is a perspective view showing the throttle device at the angle of view changed;
FIG. 10 is a top view of the throttle device;
FIG. 11 is an external view of the throttle device with a gear mounting section
removed from the gear cover;
FIG. 12 is an explanatory view showing the full-closed stopper and the default
stopper in mounted state, in which FIG. 12A is a partial view taken in the direction
of the arrow A of FIG. 11; and FIG. 12B is a sectional view taken along line B—B
of FIG. 12A;
FIG. 13 is a sectional view taken along line C—C of FIG. 6;
FIG. 14 is a sectional view of the motor casing of FIG. 13 off the motor;
FIG. 15 is an exploded perspective view of the throttle device pertaining to
the embodiments;
FIG. 16 is an exploded perspective view, partly enlarged, of the throttle device
shown in FIG. 15;
FIG. 17 is an exploded perspective view showing the component of FIG. 16 viewed
from a different direction;
FIG. 18 is a perspective view of the inside of the gear cover used in the embodiments;
FIG. 19 is an exploded perspective view of a throttle sensor mounted inside
the gear cover;
FIG. 20 is an exploded perspective view of the throttle sensor of FIG. 19 viewed
from a different direction;
FIG. 21 is a longitudinal sectional view of the gear cover;
FIG. 22 is a plan view of the gear cover viewed from inside;
FIG. 23 is a plan view of a terminal clamping plate which is a part of the gear cover;
FIG. 24 is a perspective view of the terminal clamping plate;
FIG. 25 is a perspective view of the terminal clamping plate viewed from a different direction;
FIG. 26 is a perspective view of a terminal (wiring) secured by resin molding
of the fixing plate;
FIG. 27 is an explanatory view showing the operation of the throttle sensor
used in the embodiments; and
FIG. 28 is an explanatory view showing the operation of the throttle sensor
used in the embodiments.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of this invention will be explained with reference
to the accompanying drawings.
First, referring to FIG.
1 and FIG. 2, the principle of the electronically
controlled throttle device (the throttle device of an automotive internal-combustion
engine) fitted with a default mechanism pertaining to one embodiment of this invention
will be explained. FIG. 1 is a perspective view schematically showing the throttle
valve power transmission and default mechanism in the present embodiment; and FIG.
2 is an explanatory view equivalently showing the principle of operation thereof.
In FIG. 1, the amount of air flowing in the direction of the arrow in an intake
air passage
1 is adjusted in accordance with the amount of opening of a
disk-like throttle valve
2. The throttle valve
2 is secured by a
screw to a throttle valve shaft
3. On one end of the throttle valve shaft
3 is mounted a final gear (hereinafter referred to as the throttle gear)
43 of a reduction gear mechanism
4 which transmits the power of the
motor (the electric actuator)
5 to the throttle valve shaft
3.
The gear mechanism
4 is comprised of, beside the throttle gear
43,
a pinion
41 mounted to the motor
5 and an intermediate gear
42.
The intermediate gear
42 includes a large-diameter gear
42a which
meshes with the pinion gear
41, and a small-diameter gear
42b
which meshes with the throttle gear
43, both being rotatably mounted
on a gear shaft
70 fixedly attached on the wall surface of a throttle body
100 as shown in FIG.
3.
The motor
5 is driven in accordance with an accelerator signal regarding
with the amount of depression of the accelerator pedal and a traction control signal;
the power from the motor
5 is transmitted to the throttle valve shaft
3
through the gears
41,
42 and
43.
The throttle gear
43 is a sector gear, which is fixed on the throttle
valve shaft
3, and has an engagement side
43a for engagement
with a projecting portion
62 of the default lever
6 described below.
The default lever
6 is for use in the default opening setting mechanism
(which serves as an engagement element for setting the default opening), which
is rotatably fitted on the throttle valve shaft, to rotate relatively with the
throttle valve shaft
3. In the throttle gear
43 and the default lever
6, one end
8a of a spring
8 (hereinafter, in some cases,
referred to as the default spring) is retained at a spring retaining portion
6d
of the default lever
6, while the other end
8b is retained
at a spring retaining portion
43b of the throttle gear
43,
so that a projecting portion
62 on the default lever
6 side and the
engagement side
43a on the throttle gear
43 side are applied
with a spring force to mutually pull (into engagement) in the direction of rotation.
The default spring
8 functions to turn the throttle valve shaft
3
and accordingly the throttle valve
2 towards the default opening from the
full-closed position of the throttle valve.
The return spring
7 gives the throttle valve
3 a return force to
turn the throttle valve
3 back towards closing. One end (the fixed end)
7a of the return spring
7 is retained at a spring retaining
portion
100a fixed on the throttle body
100, and the other
free end
7b is retained on the spring retaining portion (projecting
portion)
61 provided on the default lever
6. The default lever
6
and a throttle gear
43 in engagement with the default lever
6 and
accordingly the throttle valve shaft
3 are turned towards closing the throttle valve.
In FIG. 1, the projecting portions
61 and
62 of the default lever
and the spring retaining portion
43b formed on the throttle gear
43 have been exaggerated for purposes of illustration. In actual use, the
springs
7 and
8 are compressed in an axial direction to a short length,
and therefore these projecting portions are formed short correspondingly to the
compressed spring length as shown in the exploded views of FIGS. 16 and 17. Furthermore,
in FIG. 1, the spring retaining portion
43b is provided on one end
of the side opposite to the gear side of the throttle gear
43 and to allow
easy view to the spring retaining portion
43b. Actually, however,
the spring retaining portion
43b is invisibly provided in the inside
(back side) of the throttle gear
43 as shown in FIG.
17. The retaining
structure for retaining one end
7b of the return spring
7
and the retaining structure for retaining one end
8a of the default
spring
8 shown in FIG. 1 are both simplified ones; actually, however, these
retaining structures are as shown in FIG.
7 and FIG.
6. Details of
the return spring
7 and the default spring
8 will be described later on.
The full-closed stopper
12 is for defining the mechanical full-closed
position of the throttle valve
2. As the throttle valve
2 is turned
towards closing to the mechanically full-closed position, one end of the stopper
retaining element (here the throttle gear
43 serves as this stopper retaining
element) fixed on the throttle valve shaft
3 contacts the stopper
12,
thereby checking the throttle valve
2 from closing further.
The default opening setting stopper (sometimes referred to as the default stopper)
11 functions to hold the amount of opening of the throttle valve
2
at a specific initial opening (the default opening) which is wider than the mechanically
full-closed position and the electrically full-closed position (the minimum opening
for control) when the ignition switch is in off position (when the electric actuator
5 is off).
The spring retaining portion
61 formed on the default lever
6 contacts
the default stopper
11 when the throttle valve
2 is at the default
opening, and functions also as a stopper contact element which prevents the default
lever
6 from further turning beyond this stopped position towards decreasing
the amount of opening (towards closing). The full-closed stopper
12 and
the default stopper
11 is comprised of an adjustable screw (an adjusting
screw), provided on the throttle body
100. Actually, as shown in FIG.
8
and FIG. 12, these stoppers
11 and
12 are disposed parallelly or
nearly parallelly in close positions where position adjustments can be made in
the same direction.
The throttle gear
43 and the default lever
6 have the following
settings. When pulled in the direction of rotation through the spring
8,
the throttle gear
43 and the default lever
6 can turn together in
an engaged state against the force of the return spring
7 within the range
of opening over the default opening as shown in FIG.
2C. Also, within the
range of opening less than the default opening, the default lever
6 is checked
from moving by means of the default stopper
11; and only the throttle gear
43 is rotatable together with the throttle valve shaft
3 against
the force of the default spring
8 as shown in FIG.
2A.
When the ignition switch is in its off position, the default lever
6
has been pushed back by the force of the return spring
7 until it is in
contact with the default stopper
11. Also the throttle gear
43 has
been pushed by the force of the return spring
7 through the projecting portion
62 of the default lever
6; in this state the throttle valve
2
is open to a position corresponding to the default opening as shown in FIG.
2B.
In this state, the throttle gear (the stopper retaining element)
43 and
the full-closed stopper
12 are kept at a specific spacing.
As the throttle valve shaft
3 is turned from this state towards opening
through the motor
5 and the gear mechanism
4, the default lever
6
turns together with the throttle gear
43 through the engagement side
43a
and the projecting portion
62, and the throttle valve
2 turns
to open to a position in which the turning torque of the throttle gear
4
and the force of the return spring
7 are balanced.
Reversely, when the throttle valve shaft
3 is turned towards closing
by a decreased driving torque of the motor
5 through the motor
5
and the gear mechanism
4, the default lever
6 (the projecting portion
61) follows the rotation of the throttle gear
43 and the throttle
valve shaft
3 until contacting the default stopper
11. Upon contacting
the default stopper
11, the default lever
6 is checked from turning
towards closing to the default opening or less. At or under the default opening
(e.g., from the default opening to the electrically full-closed position for control),
when the throttle valve shaft
3 is driven by a power from the motor
5,
only the throttle gear
43 and the throttle valve shaft
3 are disengaged
from the default lever
6, thus operating against the force of the default
spring
8. The throttle gear
43 is driven, only when checking a reference
point for control, by the motor
5 until contacting the full-closed stopper
12 which defines the mechanically full-closed position of the throttle valve.
In normal electric control, the throttle gear
43 does not contact the full-closed
stopper
12.
According to the default system, the return spring
7 works when
the throttle valve is open over the default opening because of the presence of
the default stopper
11. Therefore, the throttle device has the advantage
that, at or under the default opening, the force of the default spring
8
can be set without being affected by the force of the return spring
7, thereby
enabling to reduce the default spring load, to decrease a torque demanded by the
electric actuator, and to reduce an electric load to the engine.
In the present embodiment, both the return spring
7 and the default spring
8 are torsion coil springs; the return spring
7 being made larger
in diameter than the default spring
8, so that these springs
7 and
8 held around the throttle valve shaft
3 are disposed between the
throttle gear
43 and the wall section of the throttle body
100.
The return spring
7 and the default spring
8 are disposed oppositely
in the direction of the throttle valve shaft across the default lever
6.
In an actual device, these springs are mounted compressed in the axial direction
as shown in FIGS. 3 to
5. Both sides of the default lever
6 serve
to receive the return spring
7 and the default spring
8, retaining
the ends
7b and
8a of these springs. And a larger-diameter
coil spring (the return spring
7 in the present embodiment) has a greater
compressive stress F than the compressive stress f of the small-diameter coil spring
(the default spring
8 in the present embodiment). The compressive stresses
are set as follows.
The default lever
6, being free- or loose-fitted on the throttle valve
shaft
3, has a clearance in the fitted portion (between the outer periphery
of the throttle valve shaft
3 and the inner periphery of the default lever
6). Therefore, the default lever
6, if held between the return spring
7 and the default spring
8, will loose stability in case the compressive
stresses are the same or the coil diameter of either spring is made small to hold
the default lever
6 at about the midsection, with the result that the default
lever
6 is attached inclined.
The default lever
6, if not properly mounted as stated above, will fail
to operate without a hitch, contacting the default stopper
11 at an improper
point and accordingly resulting in a defective setting of the default opening.
In order to cope with such a problem, the return spring
7 used in the present
embodiment is increased in diameter about as large as the flange
6b which
forms the outside diameter of the default lever
6, and, besides, its compressive
stress F is set substantially greater than the compressive stress f of the default
spring
8. According to the above-described constitution, the compressive
stress F of the return spring
7 acts on the vicinity of the outer periphery
(the vicinity of the outside diameter) of the default lever
6; and moreover,
because of the relation of F>f, the default lever
6 is pressed unidirectionally
(towards the throttle gear
43 side in this case) with a uniform pressure
and therefore can be attached in a stabilized state (without tilt), thus enabling
to insure smooth default lever operation and a given default opening setting accuracy.
FIG. 3 is a sectional view of the electronically controlled throttle device
pertaining to the present embodiment taken perpendicularly to the axial direction
of the intake passage
1; FIG. 4 is a view showing the electronically controlled
throttle device of FIG. 3 taken in the same sectional position as FIG. 3 with the
gear cover having the throttle sensor removed; FIG. 5 is a sectional view of the
electronically controlled throttle device of FIG. 3 taken in the axial direction
of the intake air passage
1; FIG. 6 is a perspective view of the electronically
controlled throttle device of the present embodiment; FIG. 7 is a perspective view
showing the electronically controlled throttle device with the gear cover removed;
FIG.
8 and FIG. 9 are perspective views taken at an angle changed; FIG.
10 is a top view of the electronically controlled throttle device; FIG. 11 is an
external view of the electronically controlled throttle device with a gear mounting
section removed from the gear cover; FIG. 12 is an explanatory view showing the
full-closed stopper and the default stopper in mounted state, in which FIG. 12A
is a partial view taken in the direction of the arrow A of FIG. 11, while FIG.
12B is a sectional view taken along line B—B of FIG. 12A; FIG. 13 is a sectional
view taken along line C—C of FIG. 6, showing a positional relation between
the intake air passage of the throttle device and the motor casing; FIG. 14 is
a sectional view of the motor casing
110 off the motor; FIG. 15 is an exploded
perspective view of the electronically controlled throttle device pertaining to
the embodiments; FIG.
16 and FIG. 17 are exploded perspective views, partly
enlarged, of the throttle device shown in FIG.
15.
As shown in these drawings, a gear mounting space
102 for the gear mechanism
4 is formed on one side wall of the throttle body
100. The gear mounting
space
102 is provided with a partly deep-recessed portion
106, in
which has a bearing boss
101 for housing one of bearings
20 of the
throttle valve shaft
3. The bearing
20 is sealed by a sealing member
18 supported by a seal holder
19.
The return spring
7 is a torsion coil spring, most of which is disposed
around the bearing boss (the annular recess
106), with one end (a fixed
end)
7a bent outwardly and retained by the spring retaining portion
100a provided in the recess
106 in the throttle body side
wall as shown in FIGS. 1,
3,
9 and
11 and with the other end
7b bent outwardly and retained by a projection
61 provided
on the default lever
6 as shown in FIG. 17, thereby applying a spring force
to the default lever
6 towards closing the throttle valve. In the present
embodiment, one end
7b of the return spring
7 is accidentally
irremovably retained in a retaining hole
61a formed in the projection
61 of the default lever
6 as shown in FIG.
17.
The throttle gear
43, as is clear from FIGS. 3 to
5, and FIGS.
16 and 17, has a throttle valve shaft insertion boss
43c only on one side
which receives one end of the default spring
8. On the other hand, the default
lever
6 also is provided with a throttle valve shaft insertion boss
6f
oppositely to the boss
43c. Around these bosses
43c and
6f, the default spring
8 is arranged.
The default spring
8 of this example is also a torsion coil spring, one
end
8a of which is bent inwardly as shown in FIG.
16 and retained
in a slot
6d formed in the boss
6f of the default lever
6, while the other end
8b is bent towards the outside diameter
side and retained by the retaining projection
43b provided inside
of the throttle gear
43 as shown in FIG.
17.
The throttle valve shaft insertion hole
43d provided in the boss
43c of the throttle gear
43 has a flat surface at least on
one side. In the present embodiment, the insertion hole
43d is a
square or nearly square hole having two parallel flat surfaces. One end
3a
of the throttle valve shaft
3 has a section similar in shape to the
throttle valve shaft insertion hole
43d and the throttle gear
43
is pressed in for fixedly mounting on one end of the throttle valve shaft
3.
The default lever
6 includes a dish-type plastic section
6a
made of a reinforced plastics material and a metal flange section
6b
provided on the peripheral edge as shown in FIGS. 3 to
5,
16
and
17. The inner edge of the flange section
6b is embedded
in the outer periphery of the plastic section
6a by molding the plastic
section
6a, thereby unifying the plastic section
6a with
the flange section
6b. Projections
61 and
62 are provided
by thus molding the flange section
6b. The default lever
6
may all be molded of a resin or a metal plate.
In the present embodiment, the default lever
6 receives at its flange
section
6b the compressive stress F of the return spring
7. Also,
as shown in FIG. 16, the plastic section
6a has a boss
6f
around a through hole
6e in which the throttle valve shaft is
inserted. Around the boss
6f, there is provided an annular groove
6C in which one end of the default spring
8 is fitted. The bottom
surface of the groove
6C receives the compressive stress f of the default
spring
8, establishing the previously stated relation of F>f.
The throttle gear
43 fixed on the throttle valve shaft
3 and the
default lever (the engagement element for setting the default opening)
6
are pulled in the direction of rotation towards mutual engagement through the default
spring
8.
The throttle valve shaft
3 is provided with an external screw thread on
one end portion. After mounting the default lever
6, the default spring
8, and the throttle gear
43, the nut
17 is tightened through
the spring washer
16. In the present embodiment, the return spring
7
and the default spring
8 whose compressive stresses are in the relation
of F>f are compressed by the pressure of the throttle gear
43. It should
be noticed that the throttle gear
43 which is mounted by pressing in may
be fixed by tightening the nut
17. In this case, the return spring
7
and the default spring
8 are compressed by a tightening torque used in tightening
the nut.
The return spring
7 and the default spring
8 are coated with for
instance a tetrafluoroethylene resin coating for decreasing friction coefficient
for purposes of reducing friction. The primary purpose of this coating is to reduce
friction with a mating portion (a portion like the member and boss which contact
the springs
7 and
8 during torsional operation), thus enabling smooth
throttle valve operation by the power from the motor and reduction of motor power
consumption during operation.
In the gear mounting space
102 provided over the side wall surface of
the
throttle body
100, a rim
104 is formed unitarily with the throttle
body
100. The rim
104 serves as a frame for mounting the gear cover.
The frame
104 is formed lower than the mounting height of the reduction
gear mechanism
4 with reference to the bottom surface of the gear mounting
space
102 as shown in FIG.
4(height H of the frame
104<height
h of the reduction gear mechanism
4). The interior volume of the gear cover
103 in the direction of depth is increased by increasing the height h′
of the side wall
105 of the gear cover
103 by the thus decreased
portion of height of the frame (the rim
104), thereby enabling covering
the reduction gear mechanism
4 with the gear cover
103. Because of
adoption of the constitution described above, it has become unnecessary to provide
the throttle body side wall with the gear case having an enclosing wall which is
higher than the mounting height of the gear mechanism; and the decreased amount
of the enclosing wall of the gear case can be compensated for by the synthetic
resin gear cover
103. Consequently, the mold-cast metal throttle body
100
can not only be downsized but reduced in weight.
As a result of the decrease in height of the gear cover mounting frame
104,
in the present embodiment, the mounting height of the pinion
41, intermediate
gear
42a and throttle gear
43 of the reduction gear
4
has been increased over the frame
104. Therefore, the throttle gear
43
is protruded out over the frame
104, and can not be stopped by the full-closed
stopper
12 provided on the frame. Therefore, a projection
102a
for mounting the full-closed stopper
12 in a position where the gearing
is covered with the gear cover
103 is set unitarily with the throttle body.
The projection
102a is formed higher than the frame
104; and
on this projection
102a, th
