Electricity: electrical systems and devices – Control circuits for electromagnetic devices – Systems for magnetizing – demagnetizing – or controlling the...
Reexamination Certificate
2002-01-23
2004-09-21
Toatley, Jr., Gregory J. (Department: 2836)
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
Systems for magnetizing, demagnetizing, or controlling the...
C123S090110
Reexamination Certificate
active
06795291
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an engine valve assembly, and particularly, to an electromechanical valve assembly for an internal combustion engine.
BACKGROUND OF THE INVENTION
Automotive manufacturers are currently utilizing camless intake and exhaust valve assemblies to control fluid communication in engine cylinders of internal combustion engines. The camless valve assemblies may utilize hydraulic, pneumatic, or electromechanical means to move a valve.
It is further known that varying an engine valve dwell time (i.e., the time interval a valve is open), a valve dwell position (i.e., the amount the valve is open), a valve opening rate, a valve closing rate, and an initial opening time of a valve (i.e., valve phasing) may be used to increase fuel efficiency and lower emissions. Further, the most flexible valve assemblies may be independently actuated/controlled with respect to other valve assemblies in an engine.
Referring to
FIG. 1
, a known engine
10
having an engine head
12
and electromechanical valve assemblies
14
,
16
is shown. The engine head
12
includes an air intake line
18
and an exhaust line
20
. The valve assemblies
14
,
16
control communication between the line
18
,
20
, respectively, with an engine cylinder (not shown).
The valve assembly
14
includes a pair of solenoids
22
,
24
, and a valve
26
. The valve
26
includes a valve stem
28
and a valve head
30
. The solenoids
22
,
24
are utilized to either open or close the valve
26
. In particular, when the solenoid
24
is energized (and solenoid
22
is de-energized), the valve head
30
is moved axially away from a valve seat
32
to allow fluid communication between the intake line
18
and a cylinder (not shown). When the solenoid
22
is energized (and solenoid
24
is de-energized) the valve head
30
engages the valve seat
32
to prevent fluid communication between the intake line
18
and the cylinder. Thus, the known valve assembly
14
has a two-position valve
26
having either a full open state or a full closed state. As such, the valve assembly
14
has several operational disadvantages. In particular, the valve assembly
14
cannot precisely control a valve dwell time duration, a valve dwell position, a valve opening rate, a valve closing rate, valve phasing. Thus, the valve assembly
14
cannot be utilized to effectively increase fuel efficiency and lower emissions in an engine. Further, the valve assembly
14
does not provide for soft seating of the valve head
30
on the valve seat
32
under all operating conditions of the engine
10
including temperature extremes and control strategy variations. As a result, the valve head
30
generates undesirable noise when contacting the valve seat
32
.
Another known electromechanical valve assembly (not shown) includes an electric motor, a cam, and a poppet valve. The motor selectively rotates an output shaft that is connected to the cam. The cam converts that rotary motion of the output shaft to an axial motion of the poppet valve. This known valve assembly is capable of controlling a valve dwell time, a valve dwell position, a valve opening rate, and a valve closing rate. However, the known valve assembly suffers from several disadvantages. First, the valve assembly requires a separate cam resulting in increased component and manufacturing costs. Further, the valve assembly requires a relatively large package space since a separate cam is utilized for each poppet valve.
SUMMARY OF THE INVENTION
The present invention provides an electromechanical valve assembly for an internal combustion engine.
The electromechanical valve assembly in accordance with the present invention includes a rotor centered about a first axis having a bore extending generally axially therethrough. The valve assembly further includes a stator operatively disposed about the rotor for producing a torque to cause rotation of the rotor about the first axis. Finally, the valve assembly includes a valve having a valve stem and a valve head. The valve stem extends generally axially through the bore of the rotor. The valve is also configured to move generally axially. responsive to the rotation of the rotor to selectively engage and disengage the valve head with a valve seat of the engine. In particular, the valve stem may be threadably engaged with the rotor. Further, the valve stem may have multiple lead engagement with the rotor.
A control system for a linear actuated electromechanical valve assembly is also provided. The control system includes a valve controller for generating a commanded valve position signal to control the incremental axial position of the valve. The valve controller can also vary a valve operational parameter. In particular, the valve operation parameter includes one or more of the following: a valve dwell time, a valve opening rate, a valve closing rate, a valve dwell position, and valve phasing. The control system also includes a position sensor that generates a signal responsive to an axial position of the valve.
A method for current recirculation (i.e., energy recovery) in electromechanical valve assemblies disposed in an internal combustion engine is also provided. The current recirculation methodology is a regenerative method that reduces the energy requirement of electromechanical valves during actuation of the valves. The method includes providing a first electromechanical valve assembly having first and second stator phases selectively connected between a first node and ground. The method further includes providing a second electromechanical valve assembly having third and fourth stator phases selectively connected between the first node and ground. The method further includes generating a braking current in the first and second stator phases of the first electromechanical valve assembly. Finally, the method includes connecting the third and fourth stator phases of the second electromechanical valve assembly to the first node to direct the braking current into the third and fourth stator phases as an accelerating current.
The electromechanical valve assembly and the control system related thereto, represent a significant improvement over conventional valve assemblies and control systems. In particular, the inventive valve assembly and control system enable the precise control of a valve dwell time, a valve opening rate, a valve closing rate, a valve dwell position, and valve phasing. As a result, the inventive valve assembly allows for increased fuel efficiency and lower emissions in an engine as compared with conventional valve assemblies. Further, the position of the valve head may be accurately controlled for soft seating with a valve seat, resulting in reduced engine noise. Still further, the valve assembly may be packaged in a relatively small package volume allowing automotive designers increased flexibility in placement of the engine. Finally, the inventive method of current recirculation provides for decreased electrical energy consumption by the inventive valve assembly as compared with conventional electromechanical valve assemblies.
These and other features and advantages of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.
REFERENCES:
patent: 3896346 (1975-07-01), Ule
patent: 5150020 (1992-09-01), Ueda et al.
patent: 5318064 (1994-06-01), Reinicke
patent: 5460129 (1995-10-01), Miller et al.
patent: 5765513 (1998-06-01), Diehl et al.
patent: 5964192 (1999-10-01), Ishii
patent: 6224034 (2001-05-01), Kato et al.
Benenson Boris
Ford Global Technologies LLC
Toatley , Jr. Gregory J.
LandOfFree
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