Internal-combustion engines – Engine speed regulator – Open loop condition responsive
Reexamination Certificate
1999-11-11
2001-09-11
Kwon, John (Department: 3747)
Internal-combustion engines
Engine speed regulator
Open loop condition responsive
C123S396000
Reexamination Certificate
active
06286481
ABSTRACT:
TECHNICAL FIELD
This invention relates to electronic valve control systems and more particularly to an electronic throttle control system for an internal combustion engine.
BACKGROUND
Valve assemblies for engines and related systems typically utilize rotatable valve members in fluid flow passageways to assist in regulating fluid flow through them. For example, throttle valve members are positioned in the air induction passageways into internal combustion engines. The valve assemblies are controlled either mechanically or electronically and utilize a mechanism which directly operates the valve member.
For electronic throttle control systems, it is desirable to have a failsafe mechanism or system which activates the throttle valve in the event that the electronic control or electronic system of the vehicle fails. There are known electronic throttle control systems which have failsafe mechanisms for closing the throttle valve or moving it to a slightly open position in the event of an electronic failure in the vehicle. Some of these mechanisms utilize one, two or more spring members in order to activate the failsafe system.
It would be desirable to have an electronic valve control system with an improved failsafe or limp-home mechanism and which provides an improved assembly and system with reduced cost and improved reliability.
SUMMARY OF THE INVENTION
The present invention provides an electronic throttle control assembly having a housing with a motor, a gear train and throttle valve. A throttle plate is positioned on a throttle shaft and the plate and shaft are positioned in the engine or air induction passageway, such that the throttle plate regulates airflow into the engine.
The operation of the throttle valve is accomplished by a gear train assembly driven by a reversible DC motor. The motor is regulated by the electronic control unit of the vehicle which in turn is responsive to the input of the vehicle operator or driver. A throttle position sensor is included in a housing cover and feeds back the position of the throttle plate to the electronic control unit.
In the operation of the throttle valve, a gear connected to the motor operates an intermediate gear, which in turn operates a sector gear which is connected to the throttle body shaft. The sector gear is biased by a main spring member towards the closed position of the throttle valve. In the event of an electronic failure during operation of the vehicle with the throttle valve open, the main spring member will return the throttle valve toward the closed position.
A default spring member is attached to the sector gear and a lever member. The lever member has an arm member which is positioned to make contact with an adjustable screw member or stop member in the housing. As the sector gear is rotated towards the closed valve position, the arm member contacts the screw or stop member and prevents further rotation of the sector gear, throttle shaft and throttle plate. This position is adjusted to provide a slight opening of the throttle valve—i.e. a “failsafe” position so the vehicle can still be operated and the driver can “limp-home.”
In order for the throttle valve to be rotated to its closed position, the motor is operated in order to overcome the force of the default spring member. The screw or stop member, in combination with a shoulder on the sector gear member, prevent the sector gear from over rotating and the throttle valve from being forced beyond its closed position.
If the throttle valve is in its closed position when an electronic failure occurs, the default spring member acts on the sector gear to open the throttle valve slightly to the failsafe position. The force of the default spring member is greater than that of the main spring member.
If a screw member is used as the stop member, then the angle of the throttle valve in the failsafe position can be adjusted as desired.
Other features and advantages of the present invention will become apparent from the following description of the invention, particularly when viewed in accordance with the accompanying drawings and appended claims.
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Bos Edward Albert
Saunders Mark Alan
Semeyn, Jr. Mark Warner
Drouillard Jerome R.
Ford Global Technologies Inc.
Kwon John
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