Electrically controlled actuator apparatus and method

An electrically controlled actuator includes a rotor detachably mounted on a rotating shaft, and a stator disposed around the rotor. A fluid flow plate is mounted on the rotating shaft and opens/closes a fluid passageway. A spiral spring is mounted on one end of the rotating shaft. When the rotor is rotated, the fluid flow plate regulates a fluid flow in the fluid passageway. An electrical control current is received in the actuator and is converted to a magnetic torque to rotate the rotor, while the spiral spring is increased in tension. The spiral spring opposes the rotation of the rotor so as to control the position of the fluid flow plate. The rotor includes two symmetric tips extended from two curved outer surfaces at two leading edges of the rotor. An air gap is defined between the inner surfaces of the stator and the outer surfaces of the rotor. The air gap becomes narrower when the rotor is rotated into a space between two poles of the stator.

FIELD OF THE INVENTION 
The present invention relates to a fluid flow metering device, more 
particularly, to an electrically controlled actuator which is integrated 
into a valve body, such as a carburetor body or a throttle body of an 
internal combustion engine or the like applications. 
BACKGROUND OF THE INVENTION 
In an internal combustion engine, an engine running speed is often varied 
due to the changes of output loads. One of the goals is to maintain a 
constant engine speed during the change of the load. Another goal is to 
adjust an engine speed when it is desired. The speed adjustment allows 
lower speed operation at light engine loads and higher speed operation at 
greater engine loads. Thus, a quiet operation with a light engine 
horsepower demand is allowed. 
To achieve these goals, an electrically controlled actuator is often used 
to maintain the engine speed or adjust the engine speed via regulating the 
amount of the engine combustion fluid, such as air/fuel mixture. An 
electrical control current is sent to an electrically controlled actuator 
which converts the electrical control current to magnetic torques so as to 
actuate the electrically controlled actuator. The actuator then regulates 
the ratio of fuel/air mixture in a carburetor, or regulates the amount of 
air in a throttle body, or controls the amount of fluid in the other types 
of fluid flow metering devices. The change of the fuel/air mixture ratio 
or the change of the amount of air causes the engine to maintain its 
running speed or adjust its running speed. 
The electrical control current sent to the actuator is usually generated by 
a microprocessor or digital/analog control methods. The microprocessor 
generates the electrical control current according to an output of an 
engine speed sensor. The sensed signal is sent to the microprocessor where 
calculations are made to correct errors of the air/fuel mixture ratio of a 
carburetor, or errors of the air amount of a throttle body, or errors of 
the fluid amount of the other types of fluid flow metering devices. The 
errors are used to determine whether the electrical control current sent 
to the actuator should be raised or lowered. Then, the electrical control 
current, with the result of the calculations and determination, is 
generated by the microprocessor and sent to the actuator. 
Various rotary electrically actuated devices for regulating fluid flow, 
such as air/fuel mixture or pure air, have been provided in the art. These 
electrically actuated devices receive an electrically control current 
determined from various engine operating parameters and act like a valve 
regulating the fluid flow supplied to the engine. Oftentimes, these 
devices are complicated in structure which includes a lot of components 
and is often difficult to manufacture. As a result, these devices are 
often very expensive. In addition, due to the complexity of the structure, 
performances of the device are often not very satisfied. One of the main 
performances is to maximize a rotating range of a fluid flow plate while 
minimizing the package size of the actuator, so that the regulating range 
of the actuator is maximized while minimizing the package size of the 
actuator. The physical size of the conventional devices which can obtain 
the same angular displacement is often about two times of the physical 
size of the present invention. Another performance is to linearize the 
current-load curve, the input-output curve of the fluid flow metering 
system. The current-load curve characterizes the regulation performance of 
the actuator. The more linear the curve is, the better the regulation of 
the fluid flow is. The current-load curve of these conventional devices is 
not linear so that the regulation performance is not very satisfied. 
Therefore, there is a need for an electrically controlled actuator which 
has a simple structure thus less expensive and has better performance with 
ensured durability and reliability. 
SUMMARY OF THE INVENTION 
The present invention relates to a fluid flow metering device, more 
particularly, to an electrically controlled actuator which is integrated 
into a valve body, such as a carburetor body or a throttle body of an 
internal combustion engine or other like applications. 
In one embodiment of the present invention, the actuator comprises: 
a rotor, detachably mounted on a rotating shaft through a center bore of 
the rotor, having at least two symmetric curved outer surfaces, at least 
two side surfaces, and at least two symmetric tips extended from the 
curved outer surfaces at two leading edges of the rotor; 
a stator, disposed around the rotor, having at least two symmetric curved 
inner surfaces corresponding to the curved outer surfaces of the rotor, an 
air gap being defined between the inner surfaces of the stator and the 
outer surfaces of the rotor; 
a fluid flow plate being mounted on the rotating shaft, so that the fluid 
flow plate rotates with the rotor, the plate being further disposed in a 
fluid passageway, so that the plate closes the fluid passageway when the 
rotor is in an unactuated position, and the plate opens the fluid 
passageway when the rotor is in an actuated position; and 
a spiral spring being detachably mounted on one end of the rotating shaft 
proximate to the rotor, the spring being increased in tension when the 
rotor rotates from the unactuated position to the actuated position, the 
spring opposing rotation of the rotor, so that the rotor is forced to 
rotate back to the unactuated position by the spring when the actuator is 
unactuated. 
One advantage of the present invention is that the structure of the 
actuator is much more simple, and there are only a few parts in the 
actuator. 
Still in one embodiment, the rotating shaft has a cylindrical shape and 
includes means for positioning the rotor on the shaft both axially and 
rotationally. The center bore of the rotor has a locating feature, such as 
a locating mark, etc., so that the rotor is slid on the shaft only in one 
direction. Since the leading edge of the rotor is chamfered, one advantage 
of having the locating feature is that it is easy to assemble the rotor on 
the shaft. 
Further in one embodiment, an angle between the unactuated position and the 
fully opened position of the fluid flow plate is about 75.degree.. It is 
due to the extended tips at the leading edges which, in conjunction with a 
varying air gap, give the actuator extra angular displacement, therefore, 
the actuator has more regulating range for its size than the prior art. 
Yet in one embodiment, the actuator further comprises electrical input and 
output ports for conducting an electrical control current to actuate or 
unactuated rotation of the rotor, and a bobbin assembly. An electrical 
wire is wound around the bobbin assembly. The bobbin assembly is mounted 
between two poles of the stator. The electrical wire has two ends which 
are disposed at the input port and the output port of the actuator. 
Still in one embodiment, one end of the spiral spring is detachably mounted 
on the bobbin assembly, and the other end of the spiral spring is bent to 
detachably mount proximate a first end of the rotating shaft. The shaft 
retains the other end of the spring by a press fit which gives positive 
assembly feedback and retains the spring from interfering with the rotor 
or falling off from the shaft. Thus, only one spring is required to create 
a torque which is used to balance with the magnetic torque caused by the 
electrical control current. In addition, the air gap between the inner 
surfaces of the stator and the outer surfaces of the rotor becomes smaller 
when the rotor moves into a space which is defined between two poles of 
the stator, and the air gap becomes larger when the rotor moves out of the 
space defined between the two poles of the stator. The spiral spring and 
the non-uniform air gap help linearize the current-load curve. 
Further in one embodiment, the stator includes means for mounting the 
stator to a valve body, such as a carburetor body or a throttle body, 
which defines the fluid passageway. The mounting means includes a 
plurality of screw captive slots disposed on an outer surface of the 
stator, and a plurality of screws are received in the screw captive slots. 
One end of each of the screws is secured into the valve body. A main body 
of the screw is received into each of the screw captive slots. The other 
end of the screws has a flat end to tightly press the stator onto the 
valve body. The mounting means further includes a recess portion which is 
disposed on the outer surface of the valve body and a projecting portion 
which is extended out of two poles of the stator. While assembling, the 
projecting portion of the stator is lined up with the recess portion of 
the valve body. Accordingly, it is easy to align the stator to the valve 
body in the assembly. Furthermore, the mounting means substantially 
eliminates the relative movements between the valve body and the stator. 
Still in one embodiment, the actuator includes means for securing the rotor 
onto the rotating shaft. The securing means includes a push-on stud 
receiving clip. The securing means prevents the rotor from falling off 
from the rotating shaft when the rotor rotates. 
Yet in one embodiment, there are at least two sets of bearings disposed 
between the rotating shaft and the valve body. One set of the bearings are 
disposed in the valve body closer to the rotor, and the other set of the 
bearings are disposed in the valve body away from the rotor. The bearings 
keep a uniform friction dampening so as to provide a repeatable, reliable 
governing control. Further, the bearings are sealed ball bearings. The 
seal is to prevent air entrance that would adversely effect the air/fuel 
ratio, or the air amount, or the other types of fluid amount. Furthermore, 
radial ball bearings are preferably used because of their ability to 
withstand the shaft deflections and corrosion by gas and oil. 
Further in one embodiment, a microprocessor is used to generate an 
electrical control current for the actuator to control the engine speed. 
The microprocessor generates the electrical control current according to a 
voltage signal of a generator. The frequency of the voltage signal is 
proportional to the engine speed, so that the engine speed is sensed, sent 
to the microprocessor, and is consequently controlled by the actuator. 
These and various other advantages and features of novelty which 
characterize the invention are pointed out with particularity in the 
claims annexed hereto and forming a part hereof. However, for a better 
understanding of the invention, its advantages and objects obtained by its 
use, reference should be had to the drawings which form a further part 
hereof, and to the accompanying descriptive matter, in which there is 
illustrated and described a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention illustrates an electrically controlled actuator. This 
design has a wide variety of applications in electro-magnetic control 
devices which have the similar problems. 
FIG. 1 illustrates a perspective view of an electrically controlled 
actuator 40 in accordance with the present invention. Part of the actuator 
40 is covered by a cover 42 so as to prevent dirt or particles, such as 
metal particles, from degrading the actuator performance by entering some 
air gaps. 
FIG. 2 shows an exploded view of the electrically controlled actuator 40 
shown in FIG. 1. A rotor 48 is detachably mounted on a rotating shaft 50 
through a bore 52 of the rotor 48. The rotating shaft 50 is supported on a 
valve body 46 by a plurality of bearings (see details below in FIG. 13). 
The valve body 46 can be a carburetor body or a throttle body of an 
internal combustion engine. It is appreciated that any other types of 
valve body can be used to incorporate with the actuator 40. The rotor 48 
is secured on the rotating shaft 50 by a push-on stud receiving clip 54. 
It is appreciated that other types of securing means can be used to secure 
the rotor 48 on the rotating shaft 50. Thus, the clip 54 prevents the 
rotor 48 from sliding off from the rotating shaft 50 when the rotor 48 
rotates. 
In both FIGS. 2 and 7, it is shown that the rotor 48 has two symmetric 
curved outer surfaces 56, 58. Two symmetric tip portions 60,62 extended 
from the curved outer surfaces 56,58 beyond two side surfaces 64,66. The 
bore 52 is disposed proximate to the central of the rotor 48. The bore 52 
has a flat surface 68 (see FIG. 7) which contacts with a corresponding 
flat surface 70 (see FIG. 5) of the rotating shaft 50. The rotor 48 is 
stopped from moving further toward a back end 72 of the rotating shaft 50 
due to a wall created between the flat surface 70 and a flat surface 74 of 
the shaft 50. The clip 54 press-fits on a flat surface 76 of the shaft 50 
so as to secure the rotor 48 onto the shaft 50. 
Still in FIG. 2, a stator 78 is detachably mounted on the valve body 46. 
The stator 78 is disposed around the rotor 48. Two symmetric curved inner 
surfaces 80,82 correspond to the curved outer surfaces 56,58 of the rotor 
48. An air gap 84 (see FIG. 3) is defined between the inner surfaces 80,82 
of the stator 78 and the outer surfaces 56,58 of the rotor 48. The curved 
outer surface 56,58 and the tip portions 60,62 are disposed outside the 
space between two poles 86,88 of the stator 78 when the actuator 40 is in 
an unactuated position (see FIG. 11). The tip portions 60,62 start to move 
into the space between the poles 86,88 when the actuator 40 is actuated 
due to the magnetic torque created between the rotor 48 and the stator 78. 
Accordingly, edges 90,92 at the tip of the tip portions 60,62 are often 
called a leading edge as the edges 90,92 lead the curved outer surfaces 
56,58 into facing with the curved inner surfaces 80,82 of the stator 78. 
The tip portions 60,62 increase the pole face between the stator 78 and 
the rotor 48 so that the rotation angle of the rotor 48 relative to the 
stator 78 is increased by an angle defined between the leading edge 90 (or 
92) and the side surface 64 (or 66). The maximum rotation angle of the 
rotor 48 relative to the stator 78 is about 75.degree.-78.degree.. As a 
result, the rotating shaft 50 can be rotated at maximum about 
75.degree.-78.degree.. 
The stator 78, as shown in FIGS. 2, 9, and 10, is disposed as a horizontal 
U-shaped stator. The stator 78 has two projection portions 94,96 extending 
from the poles 86,88, respectively. The two projection portions 94,96 are 
received in a recess 98 disposed on the valve body 46. The stator 78 and 
the valve body 46 are aligned to each other when the outer surfaces of the 
projection portions 94,96 are lined up and contact the walls 100,102 
around the recess 98. In addition, the stator 78 has four screw captive 
slots 104a-d. The screw captive slots 104a-d are disposed on four corners 
of the U-shaped stator 78. When the stator 78 is aligned to the valve body 
46, the four slots 104a-d are aligned to four mounting recesses 106a-d. 
Four screws 108a-d are disposed in the slots 104a-d. One end 110a-d of the 
screws 108a-d are secured in the mounting recesses 106a-d, and the other 
end 112a-d of the screws 108a-d have a cap-shape which is used to press 
the stator 78 toward the valve body 46 so as to tightly secure the stator 
78 onto the valve body 46. 
A bobbin 114 is mounted on the stator 78 between the two opposite arms of 
the U-shape. An electrical wire (not shown) is wound around the bobbin 
114. The electrical wire conducts an electrical control current from a 
microprocessor 116 (see FIG. 15) via input and output ports 118,120 of the 
actuator 40. The electrical current is converted to the magnetic torques 
so as to rotate the rotor 48. The magnetic torques are varied according to 
the different electrical currents thus causing various rotation angles. 
In FIGS. 2 and 3, a spiral spring 122 is detachably mounted on the rotating 
shaft 50, between the clip 54 and a projection section 124 of the shaft 50 
(see FIG. 5). An inner end portion 126 of the spring 122 is bent to a flat 
shape. The inner end portion 126 is thus biasedly passed through the 
projection section 124 and is received in the lower surface 76 of the 
shaft 50. An outer end portion 128 of the spring 122 is bent 180.degree. 
to form a C-shape. The outer end portion 128 hocks into a slot 130 
disposed on the bobbin 114. Accordingly, when the rotor 48 rotates under 
the stator 78, the spring 122 is biasedly extended and increased in 
tension. The spring has the tendency to counter-rotate the rotor 48. Thus, 
the rotor 48 rotates to a position where the torque created by the spring 
tension force balances with the magnetic torques and other shaft torques 
created by the application or system. It is appreciated that another types 
of tension means can be used to balance the magnetic torques and other 
shaft torques created by the application or system. 
The air gap 84 (see FIG. 3) between the curved inner surfaces 80,82 of the 
stator 78 and the curved outer surfaces 56,58 of the rotor 48, when the 
rotor 48 moves under the stator 78, is not uniform. The air gap 84 becomes 
smaller when the curved outer surfaces 56,58 of the rotor 48 move into the 
space between the poles 86,88 of the stator 78, and the air gap 84 becomes 
larger when the curved outer surfaces 56,58 of the rotor 48 move out of 
the space between the inner surfaces 80,82 of the poles 86,88 of the 
stator 78. The smaller the gap is, the denser the magnetic flux is, so 
that the torques created from the additional magnetic flux due to the 
smaller gap compensate the unbalanced torques created during the rotation 
of the rotor 48. Accordingly, the current-load curve, which shows the 
relationship between the input, electrical currents, and the output, fluid 
control, is still substantially linear. 
In FIG. 3 shows an elevation side view without the cover 42. The screws 
108a-d tightly secure the stator 78 onto the valve body 46. The spring 122 
is attached to the rotating shaft 50 at the inner end portion 126 and is 
attached to the bobbin 144 at the outer end portion 128. 
In FIG. 4, a fluid flow plate 130 (see FIGS. 11 and 12) is mounted on the 
rotating shaft 50 at a reduced section 132 (also see FIG. 5) via two 
mounting screws 134,136. The mounting screws 134,136 are received in two 
screw slots 138,140 on the shaft 50, respectively. Thus, the plate 130 
rotates with the rotating shaft 50. The plate 130 closes a fluid 
passageway 44 (see FIGS. 11-13) when the actuator 40 is not actuated. As 
also shown in FIG. 11, where the actuator 40 is in an unactuated position, 
the plate 130 has a predetermined tilt angle, .beta., e.g. 15.degree., 
from a vertical line as shown in FIG. 11. The tilt angle .beta. can be 
varied as desired. For example, if the maximum rotating angle of the plate 
between the unactuated position and the full open position (i.e. the plate 
parallel to the fluid flow, as shown in FIG. 12) is 75.degree., then the 
tilt angle .beta. can be set to 15.degree.. 
In FIG. 13, a longitudinal bore 141 of the valve body 46 is shown. The 
rotating shaft 50 is substantially disposed and fits in the bore 141. The 
longitudinal bore 141 intersects the fluid passageway 44. The fluid flow 
plate 130 is disposed at the intersection, so that the fluid flow plate 
130 closes or opens the fluid passageway 44 when the rotating shaft 50 
rotates with the fluid flow plate 130. The rotating shaft 50 is held in 
place by two sets of sealed ball bearings 142,144 (FIG. 4). One set of the 
ball bearings 142 is disposed between the rotating shaft 50 and the valve 
body 46 closer to the rotor 48. The other set of the ball bearings 144 is 
disposed between the shaft 50 and the valve body 46 at the back end 72. 
The ball bearings 142,144 are sealed from outside to prevent air entrance 
that would adversely effect the fluid conducted in the fluid passageway 
44. For example, the air may change the air/fuel ratio in a carburetor 
application or may change the existing air amount in a throttle body 
application. The bearings 142,144 can also reduce the deflection of the 
rotating shaft 50 during the rotation. In addition, the bearings 142,144 
absorb any deflection which may occur without introducing any inconsistent 
friction to the actuator 40. 
The deflection of the shaft 50 can further be reduced by the line up 
between the projecting portions 94,96 and the recess walls 100,102. 
The stator 78 and the rotor 48 are made of powdered metal which comprises 
of a 7.0 g/cc minimum density nearly carbon free material and 0.45% 
phosphorus. It is appreciated that other type of components can be used in 
place of the powdered metal. 
FIG. 6 shows the shaft 50 in an elevation side view of FIG. 5. 
FIG. 8 is an elevation side view of the rotor 48 as shown in FIG. 7. 
FIG. 10 is an elevation side view of the stator 78 as shown in FIG. 9. 
In FIG. 14, a current-rotating angle curve of the present invention is 
shown. When the control current is above a certain amount, such as 1.2 
Amp, the curve becomes linear so that a good control performance to 
control the rotation of the fluid flow plate is provided. It is also shown 
that the maximum rotating angle, the angle between the unactuated position 
and the fully opened position of the fluid flow plate, is about 75.degree. 
to 78.degree.. 
FIG. 15 shows an electrical control device incorporated with the actuator 
40. The electrical control device, such as a microprocessor 116, sends the 
electrical control current to the input port 118 of the actuator 40. The 
microprocessor 116 receives a signal from a sensor 145. The sensor senses 
an engine speed by sensing a voltage output of a generator 146 as shown in 
FIG. 15. The sensed signal from the sensor 145 is sent to the 
microprocessor 116. It is appreciated that other methods of detecting the 
engine speed can be used. 
After the sensed signal is sent to the microprocessor 116, calculations are 
made to do corrections in the electrical control current which is sent to 
the actuator 40. The correction determines whether the current is to be 
raised or lowered. The greater the control current, the more magnetic 
torque is produced, and the more rotating angle is turned. For example, 
the sensor 146 senses the engine speed and sends it to the microprocessor 
116. The microprocessor 116 determines the correction and sends the proper 
amount of current to the input port 118 of the actuator 40 to more open or 
more close the fluid passageway 44 so as to regulate the amount of fluid 
supplied to an engine 150. 
A software is installed in the microprocessor 116, which includes an 
algorithm to determine the amount of control current sent to the actuator 
40 according to the sensed engine speed. 
It is to be understood, however, that even though numerous characteristics 
and advantages of the present invention have been set forth in the 
foregoing description, together with details of the structure and function 
of the invention, the disclosure is illustrative only, and changes may be 
made in detail, especially in matters of shape, size and arrangement of 
parts within the principles of the invention to the full extent indicated 
by the broad general meaning of the terms in which the appended claims are 
expressed.