Internal-combustion engines – Engine speed regulator – Having plural throttle valve structure
Reexamination Certificate
2002-11-14
2003-09-23
Solis, Erick (Department: 3747)
Internal-combustion engines
Engine speed regulator
Having plural throttle valve structure
C123S399000, C251S129110, C251S305000
Reexamination Certificate
active
06622695
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-355010 filed on Nov. 20, 2001, Japanese Patent Application No. 2001-363119 filed on Nov. 28, 2001, Japanese Patent Application No. 2001-363142 filed on Nov. 28, 2001 and Japanese Patent Application No. 2001-372540 filed on Dec. 6, 2001.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an intake control system of an internal combustion engine, the intake control system being capable of controlling quantity of intake air for each cylinder by controlling opening and closing of intake control valves disposed in intake passages of the engine.
2. Description of Related Art
Conventionally, a known intake control system, which is provided with intake control valves disposed in intake passages of an internal combustion engine, controls quantity of intake air for each cylinder by controlling opening and closing of the intake control valves respectively, besides a throttle valve disposed in the engine.
In such a kind of intake control system, the intake control valves disposed in the intake passages of the respective cylinders are capable of being controlled to open and to close by actuators respectively and independently. Therefore, it is possible to prevent back flow of intake air, which occurs in an intake stroke when an engine revolution is in a low speed range, by controlling the opening and closing timing of the intake control valves in correspondence with operating conditions of the engine. As a result, an output of the engine is improved. In addition, it is possible to reduce a pumping loss, which increases when the engine is under a partial load especially when the engine is idling, by controlling the opening and closing timing of the intake control valves in correspondence with operating conditions of the engine. Thus, fuel consumption is reduced, as is commonly known. When the engine is under a partial load, especially when the engine is idling, intake air is drawn through one port alone. Therefore, swirls or tumbles are generated in the cylinder and atomization of fuel is improved. Accordingly, the fuel is mixed with air efficiently, and fuel combustion is improved.
Conventionally, a 90-degree rotating type rotary solenoid actuator, an R/S actuator, is used as an actuator that drives the intake control valve to open and to close. The R/S actuator holds the intake control valve at a neutral position where an intake passage is half opened, when current is not supplied thereto. When the current is supplied, the R/S actuator drives the intake control valve from the neutral position to a direction to open or to close the intake control valve in correspondence with strength and direction of the current.
In such a case in which the R/S actuator that holds the intake control valve at the neutral position when the current is not supplied thereto is employed, safety is ensured because the engine is capable of operating without closing the intake passage even if the current is not supplied to the R/S actuator because of a breakdown and the like. In addition, the opening and closing directions of the intake control valve are changed by altering the direction of the current supply. Therefore, the intake control valve is capable of being driven from a full opening position to a full closing position quickly, and vice versa.
However, when the R/S actuator is used to control the opening and closing of the intake control valve, the R/S actuator needs the current supply invariably even when the intake control valve is held at a full opening position and the opening and closing control is not performed. As a result, power consumption is increased.
As a solution for such a problem, Japanese Patent Laid-Open Publication No. H06-58192 discloses an intake control system that reduces the power consumption by reducing current supply to an R/S actuator while an intake valve is closed, as intake characteristics of an engine are not affected even if the intake control valve is opened or closed while the intake valve is closed.
FIG. 8A
is a longitudinal cross-sectional view showing an intake control device of the conventional intake control system and
FIG. 8B
is a cross-sectional view showing the intake control device along the line VIIIB—VIIIB in FIG.
8
A. The conventional R/S actuator
20
that controls the intake control valve
10
comprises a support shaft
21
, a magnetic member
22
, electromagnetic coils
23
,
24
, permanent magnets
25
,
26
and the like as shown in
FIGS. 8A and 8B
. The support shaft
21
connected with a support shaft
11
of the intake control valve
10
is held in a casing
27
rotatably. The magnetic member
22
is press-fitted around the support shaft
21
and is formed with opposing magnetic poles symmetrically in a radial direction. The pair of electromagnetic coils
23
,
24
are disposed on inner walls of the casing
27
, facing each other across the magnetic member
22
. The pair of permanent magnets
25
,
26
are disposed on the inner walls of the casing
27
so that the permanent magnets
25
,
26
face each other across the magnetic member
22
, and the alignment thereof is perpendicular to that of the electromagnetic coils
23
,
24
.
When the electromagnetic coils
23
,
24
are supplied with current, the magnetic member
22
is rotated to a position determined by magnetic poles provided by the electromagnetic coils
23
,
24
and magnetic poles provided by the permanent magnets
25
,
26
. As a result, the support shaft
21
integrated with the magnetic member
22
is rotated, and the intake control valve
10
is rotated from a neutral position, a half opening position, toward a full opening position or a full closing position.
If the current supply to the electromagnetic coils
23
,
24
is cut off, the magnetic member
22
is attracted by the magnetic poles of the permanent magnets
25
,
26
alone. Accordingly, the intake control valve
10
is rotated to the neutral position and is stabilized there.
As explained above, the conventional R/S actuator
20
is a permanent magnet type torque motor. The permanent magnets
25
,
26
for holding the rotor
21
at the neutral position are disposed in the stator of the conventional R/S actuator
20
. The magnetic member
22
is disposed around the rotor
21
. The rotor
21
is rotated by supplying current to the electromagnetic coils
23
,
24
and is rotated from the half opening position to the full closing position or the full opening position.
Generally, mechanical inertia of its motor should be small because the R/S actuator for controlling the opening and closing of the intake control valve has to operate quickly. Therefore, large magnets are not applicable in the motor, and large torque is not acquired even if the current is supplied. Accordingly, when the rotor of the motor is held at a full closing position or at a full opening position, large current is required to hold the rotor, because a torque constant, torque generated per unit current, is small. As a result, reduction of the power consumption is not attainable.
In addition, the conventional R/S actuator uses detent torque when returning to the neutral position. Therefore, improvement of its response cannot be expected. Moreover, there are some more disadvantages, such as a high-cost, because the permanent magnets are used in the stator.
Japanese Patent Laid Open Publication H04-292528 discloses another intake control system that controls intake control valves by R/S actuators. The intake control system controls quantity of intake air by opening and closing the intake control valves once in every intake stroke in compliance with a command from an electronic control unit (ECU). However, the intake control system is not provided with sensors such as an opening degree sensor or a coil temperature sensor. Therefore, the intake control system is controlled in an open loop control and is only capable of performing the intake control with timing that is programmed in advance.
Denso Corporation
Solis Erick
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