Internal-combustion engines – Engine speed regulator – Open loop condition responsive
Reexamination Certificate
2001-12-12
2003-07-29
Vo, Hieu T. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Open loop condition responsive
C123S337000, C123S361000
Reexamination Certificate
active
06598587
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a throttle apparatus for an engine for electrically performing control for a throttle valve angular position by means of a throttle actuator.
In the recent years, according to advancing of an electronic control for an engine, there has been proposed a technology for controlling an angular position of a throttle valve by detecting a position of an accelerator pedal (accelerator operating rate) by means of an accelerator position sensor and driving a throttle actuator (DC motor, stepping motor and so forth) on the basis of an accelerator position sensor signal and a control signal, such as, a traction control signal and so forth.
Recently, in a system for electrically controlling the angular position of the throttle valve as set forth above, there have been proposed technologies, in which an angular position of the throttle valve at OFF position of an engine key (in other words, while an electric power is not supplied to a throttle actuating motor: initial throttle valve angular position) is set at an angle greater than a minimum angle of the throttle angular position (normally, an idling opening of the throttle valve in a steady state of the engine after warming up) in a control range of the throttle valve angular position, within which the throttle valve angular position is controlled by means of the throttle actuating motor (see PCT National Publication No. 2-500677(1990), Japanese Patent Application Laid-Open No. 3-271528(1991), Japanese Patent Application Laid-Open No. 4-203219(1992), for example).
One reason why the initial opening is set at the foregoing position, is to satisfy a demand for preventing sticking of the throttle valve due to deposition of a viscosity matter, ice or the like. In addition, the initial opening set forth above is intended to assure self-travel (limp home) even upon failure of a throttle control system, and to certainly provide sufficient air flow rate for preventing the engine from stalling.
An initial opening setting mechanism (occasionally referred to as default mechanism) sets a position (close to a fully closed position of the throttle valve) where a spring force of a return spring biasing the throttle valve in a closing direction and a spring force of an initial opening spring for biasing the throttle valve in an opening direction, are balanced, as the initial opening, in principle.
In the throttle apparatus having the initial opening setting mechanism of the type set forth above, when an engine key is turned-on, for example, the throttle valve is mechanically driven from the foregoing initial opening to the minimum point of motor control (position contacting with an adjusting screw) by means of the throttle actuating motor. Thereafter, an angular position of the throttle valve is controlled at a position corresponding to an engine coolant temperature and so forth.
In an engine control portion, sensors, such as an air flow sensor, a throttle position sensor and so forth, have to be provided in an air intake system. When mechanical parts, such as the throttle actuator, gear and so forth are mounted in addition to the foregoing sensors, number of parts can be increased. On the other hand, a space in the engine room is limited.
In an electronically controlled throttle apparatus (hereinafter occasionally referred to as “electronic throttle apparatus”), a technology for aggregating and rationalization of initial opening setting mechanism, such as sensor parts, actuator parts and so forth has been held immature. Therefore, optimal installation technology has been strongly demanded. Particularly, it is typical to provide a body of the air flow sensor and the throttle body, separately. When such prior art is applied to the electronic throttle apparatus, electronic control parts and mechanical parts, such as sensor parts, actuators and so forth, are straggled to increase work load in assembling operation and wiring operation in the case where the throttle apparatus is installed in the engine room. Also, it is not easy to avoid interference between the throttle apparatus and other parts due to limitation of the space in the engine room.
SUMMARY OF THE INVENTION
The present invention has been worked out in view of the drawbacks set forth above.
An object of the present invention is to provide an electronic throttle apparatus which permits aggregating of various parts and rationalization of installation, and can simplify assembling operation and wiring operation to an engine room for rationalization of an installation space.
Another object of the present invention is to guarantee stable operation of a throttle mechanism by a motor control and to enhance accuracy.
The present invention is generally constructed as follows.
At first, the present invention is directed to a mounting technology of a throttle actuating motor, a throttle position sensor and an air flow sensor.
In the first aspect of the present invention, the throttle actuating motor, the throttle position sensor detecting a throttle valve angle, and the air flow sensor located on upstream of the throttle valve and measuring an intake air flow rate are mounted on the throttle body.
With the construction of the foregoing first aspect of the present invention, parts for electronic control can be concentrically arranged on the throttle body. On the other hand, operation for assembling the air flow sensor-body and the throttle body which are otherwise formed separately, in the air intake passage, can be eliminated, so that assembling operation can be completed by single assembling operation of the throttle apparatus. On the other hand, the various external electric wiring such as the sensor output lead wire, the power source wiring, the grounding wiring and so forth can be aggregated on the closer side to the throttle body. Thus, enhancement of efficiency of the wiring connecting operation can be achieved.
In the second aspect of the present invention, in addition to the construction set forth in the first aspect of the invention, the throttle body can be designed to orient an air passage transversely when the throttle body is installed within an engine room, and formed with a casing portion of the motor and a mounting portion of the air flow sensor on an upper surface to be located on an upper side upon installation, among external walls thereof.
With the construction of the second aspect of the present invention as set forth above, the air flow sensor as an accessory of the throttle apparatus, can be taken out from the throttle body independently and easily, even after installation of the throttle body within the engine room for enhancing convenience in inspection, maintenance and exchanging. On the other hand, since the motor casing portion extends over the upper surface of the throttle body, a step is formed between the motor casing portion and the upper surface of the remaining throttle body. A space defined by the step can be effectively utilized as an installation space of the air flow sensor. Therefore, wasting of space around the throttle body can be eliminated to increase density of concentration in mounting of the parts.
In the third aspect of the present invention, in addition to the construction set forth in the first aspect of the invention, directionality of connector terminals for electrical connection with external electric wiring of the throttle actuating motor, the throttle position sensor and the air flow sensor can be matched with each other.
Various external electric wiring (sensor output line, the sensor power line, the motor line and so forth) can be lead from the engine control unit to the throttle body. Since the connector terminals of electrical connection for the external electrical wiring of the throttle actuating motor, the throttle position sensor, the air flow sensor are matched directionality so that various electric wiring are not required to be lead from different directions to make operation for establishing electrical connection quite simple.
As an optimum embodiment, according to the fourth aspect o
Kamimura Yasuhiro
Nagayama Kazuo
Sasaki Yasushi
Tomita Norio
Crowell & Moring LLP
Hitachi , Ltd.
Vo Hieu T.
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