Internal-combustion engines – Engine speed regulator – Open loop condition responsive
Reexamination Certificate
1999-11-11
2001-07-03
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Open loop condition responsive
C251S129120
Reexamination Certificate
active
06253732
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. Two lever members and two spring members are provided, all in operational association with the sector gear member. The two lever members, namely a main lever member and a default lever member, are free to rotate on the throttle shaft. A main spring member is positioned between and connected to the sector gear member and the main lever member. A default spring member is positioned between the main lever member and the default lever member.
The main spring member is grounded between the sector gear member and the main lever member. The main lever member is grounded to the housing through an adjustment screw stop member. The default spring member is grounded between the two levers.
In the event of an electronic failure during operation of the vehicle with the throttle valve in an open position, the main spring member will return the throttle valve to the default or failsafe position. The mechanism will stop at a prescribed default angle since the intermediate gear contacts the default lever and is prevented from further rotation by the default spring member.
If the throttle valve is in its closed position when an electronic failure occurs, the default spring, acting on the default lever and intermediate gear post member, rotates the intermediate gear, in turn rotating the sector gear to open the throttle valve slightly to a failsafe position. The force of the default spring is greater than that of the main spring member. At the failsafe position, the vehicle can still be operated, although at a reduced capacity. This allows the driver to “limp-home.”
The default adjustment screw can be used to change the angle of the throttle valve at the default position. Also, the two lever members and sector gear preferably are snap fit together for each assembly.
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LaRussa Joseph John
Saunders Mark Alan
Semeyn, Jr. Mark Warner
Dolinar Andrew M.
Drouillard Jerome R.
Ford Global Technologies Inc.
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