Internal-combustion engines – Engine speed regulator – Open loop condition responsive
Reexamination Certificate
2000-06-30
2002-06-11
Solis, Erick (Department: 3747)
Internal-combustion engines
Engine speed regulator
Open loop condition responsive
C310S233000, C310S248000
Reexamination Certificate
active
06401689
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electric throttle-control apparatus and a motor used in the apparatus.
In a conventional throttle system used in a car, since the throttle system is mechanically composed such that the throttle valve is opened and closed according to the operation of an acceleration pedal via a wire, the quantity of the pedal-operation directly corresponds to the open degree of the throttle valve. Recently, a highly accurate control of a throttle valve has been required from the view points of the regulations to exhaust gas, and improvements for fuel consumption, safety, and salability, and the electrical throttle-control system (hereafter referred to as an ETC system).
As shown in
FIG. 26
, National Publication of Japanese-translated version Hei-500677 (WO88/02064) discloses an apparatus for electrically controlling intake air flowing into an internal combustion engine: the apparatus including an intake air flow path
10
, a throttle valve
11
fixed to a rotatably set shaft
12
located in the intake air flow path
10
, and a first return spring
15
, which is always engaged with the shaft
12
, for applying a torque in the direction of closing the throttle valve
11
. Further, the throttle valve
11
is guided by the return spring
15
to the stop position of the minimum open angle &agr;
r
(>0) toward the stopper to which a spring-load is applied by an opposing spring
21
. In addition, a rotation-adjusting unit
13
, in which a motor is used, is controlled so as to generate torque, corresponding to torque to open the throttle valve
11
to the maximum open angle.
Also, as shown in
FIG. 27
, Japanese Patent Publication Hei 7-72503 discloses a load-adjusting apparatus including a control element
11
connected to a transmission member
4
further connected to an acceleration pedal
1
, which acts on a throttle valve
16
in an internal combustion engine, and on the electrical servo-driving unit
9
along with a target operation amount-detection element
7
attached to the transmission element
4
. Further, the control element includes an actual operation amount-detection element
12
, and the electrical servo-driving unit
9
is controlled by an electric control apparatus
22
based on the detected operation amount. Furthermore, the control element
11
, the target operation amount-detection element
7
, the actual operation amount-detection element
12
, and the servo-driving unit
19
are arranged in a throttle valve casing
24
. Moreover, the control element
11
is connected to the transmission member
4
with a connection spring
13
so as to be pressed toward a stopper
14
attached to the transmission member
4
.
Generally, when a motor receives voltage, and begins to rotate, voltage in the direction reverse to that of the received voltage is generated in the motor, due to the generation effect of the motor. This generated voltage is called a counter voltage, and is proportional to the rotational speed of the motor. Since the motor used in an electric throttle-control apparatus is controlled to rotate to the target rotational position, when the rotation approaches the target rotational position, voltage in the direction reverse to that of the rotation of the motor is applied to the motor due to the deceleration. Thus, the counter voltage is superimposed on the fed voltage, which in turn may cause an over-current flow in the motor.
In a conventional motor, the resistance of the motor is adequately set such that an over-current due to the counter voltage does not flow in the motor. Thus, the amount of current flowing in the motor and the motor-drive circuit is suppressed below a permissible level of current for the elements in the motor-drive circuit.
However, in controlling the throttle-valve position with a motor, the throttle-valve position becomes less than stable due to small fluctuations in the torque generated within the motor, these in turn appearing as fluctuations in the rotational speed of the engine. These fluctuations of the rotational speed are not only visually perceived as fluctuations of the needle on the speed meter, but are also audibly perceived. Particularly, fluctuations in idling has been a great problem.
Since the design specification regarding the deviation in torque of a motor has been prescribed by the deviation in the average torque of the motor, it has been difficult to sufficiently suppress the fluctuation of the engine rotational speed even if the motor satisfies the design specification.
This problem has been handled by implementing proper control-characteristics of an engine-control unit whose control parameters are optimally set by a parameter survey method.
However, in its execution, since it is necessary to determine an optimal control parameter set for each electronic throttle-control apparatus in which a different motor is used, this parameter survey method is not flexible.
SUMMARY OF THE INVENTION
The present invention has been achieved with consideration to the above problems, and is aimed at providing an electric throttle-control apparatus which can suppress the fluctuations of the engine rotational speed to below a small level, and especially the fluctuations in idling, by decreasing the change in the torque generated between slots of the motor used in the electric throttle-control apparatus without adjusting a control parameter set of the engine control unit. More specifically speaking, the present invention is aimed at providing a motor such that the fluctuations of the rotational speed can be suppressed to below the level of 3% (15 rpm), which cannot be visually and audibly perceived, assuming that the idling rotational-speed is 500 rpm.
As a result of the inventors' searching and analyzing malfunctions in electric throttle-control apparatuses, it has been found that employing the average torque of a motor to suppress torque fluctuation of the motor is not adequate, and clarification of the motor's behavior during the brush's transition between slots is important. That is, it has been noticed that the torque fluctuations caused during the brush's transition between slots must be suppressed to improve responses of a motor for demands of Small Step-changes in torque.
The present invention provides the following apparatuses, motors, and internal combustion engines used in an electric throttle-control, which can improve responses of a motor for demands of Small Step-changes in torque.
To achieve the above objective, the present invention provides a first electric throttle-control apparatus, which includes a motor, a speed-reduction mechanism for reducing rotational speed of the motor, and a throttle valve connected to the speed-reduction mechanism, for controlling an open position of the throttle valve by driving the motor, wherein the motor includes a commutator with a plurality of slots, and brushes; and the number of the slots in the commutator and the arrangement of brushes on the slots are set so that even and odd number slot states appear alternately in an electrical equivalent-circuit of a wire-connection among slots including the brushes while the motor rotates.
Further, the present invention provides a second electric throttle-control apparatus such that, in the above first electric throttle-control apparatus, the number of the slots of the commutator is one of odd numbers
9
,
11
, and
13
; the number of the brushes is
2
; and the brushes are arranged in a 180° opposed placement.
Furthermore, the present invention provides a third electric throttle-control apparatus such that, in the second electric throttle-control apparatus, the number of the slots of the commutator is one of odd numbers
9
and
11
.
Moreover, the present invention provides a fourth electric throttle-control apparatus such that, in the first electric throttle-control apparatus, the number of the slots of the commutator is one of even numbers
10
and
12
; the number of the brushes is
2
; and the brushes are arranged by shifting their positions from a 180° opposed placement
Fujino Shin-ichi
Fukasaku Yoshinori
Hiruta Masahiro
Ito Masaru
Shimizu Hisaya
Crowell & Moring LLP
Solis Erick
LandOfFree
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