Electromagnetic flow control valve unit

In an electromagnetic flow control valve unit, a pair of flow control valves are associated with a moving-coil linear motor to simultaneously control each fluid flow into two independent devices in accordance with an electric current applied thereto.

BACKGROUND OF THE INVENTION 
The present invention relates to electrically operated fluid control valve 
units, and more particularly to an improvement of an electromagnetic flow 
control valve unit in which a flow control valve is associated with a 
moving-coil linear motor to control the quantity of fluid flow in 
accordance with an electric current applied thereto. 
In general such a conventional electromagnetic flow control valve unit as 
described above comprises a single flow control valve for controlling the 
quantity of fluid flow from a single inlet port to a single outlet port, 
which control valve does not serve to simultaneously control each fluid 
supply into two independent devices. 
SUMMARY OF THE INVENTION 
It is, therefore, a primary object of the present invention to provide an 
improved electromagnetic flow control valve unit capable of simultaneously 
controlling each fluid supply into two independent devices such as a 
carburetor and an exhaust gas recirculation valve in a vehicle engine 
control system. 
According to the present invention briefly summarized there is provided an 
electromagnetic flow control valve unit which comprises a housing provided 
with an inlet port and first and second outlet ports, a longitudinal 
tubular core arranged within the housing and connected at its opposite 
ends to the first and second outlet ports, the tubular core being provided 
therein with a partition member which subdivides the interior of the core 
into first and second passages respectively opening into the first and 
second outlet ports and further provided with first and second axial holes 
permitting each fluid flow between the inlet port and the first outlet 
port across the first passage and between the inlet port and the second 
outlet port across the second passage, and a linear motor of the 
moving-coil type including a permanent magnet arranged within the housing 
to provide magnetic flux, a bobbin axially slidable on the tubular core, a 
moving-coil wound around the bobbin and arranged across the magnetic flux 
of the magnet to generate a linear force on the bobbin in accordance with 
an electric current applied thereto from an electric circuit, and 
resilient means for biasing the bobbin to its original position and 
connecting the moving-coil to the electric circuit. The linear motor is 
characterized in that the bobbin is formed with axially spaced first and 
second valve parts respectively cooperating with the first and second 
axial holes for controlling each quantity of fluid flow passing through 
the first and second passages.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In FIG. 1 of the drawing, there is schematically illustrated a control 
system for an internal combustion engine which includes an electromagnetic 
flow control valve unit 10 in accordance with the present invention. The 
control valve unit 10 is provided with an inlet port 10a and first and 
second outlet ports 10b and 10c. The inlet port 10a is connected through a 
passage 90 to an air port 82 located at the upstream of a venturi 81 in an 
air induction passage 80. The first outlet port 10b is connected through a 
passage 91 to a main air-bleed passage 84 of a carburetor 83, and the 
second outlet port 10c is connected through a passage 92 to a pilot port 
86 of a conventional exhaust gas recirculation valve 85. A by-pass passage 
93 is connected at its one end to passage 92 and at its other end to an 
advance port 88 adjacent to a throttle valve 87 in the air induction 
passage 80. With the arrangement described here, the control valve unit 10 
acts to simultaneously control air-fuel ratio and an amount of 
recirculated exhaust gases upon receipt of an electric signal indicative 
of operating condition of the engine thereby to purify the exhaust gases 
with the minimum power losses and fuel consumption. 
As shown in FIG. 2, the control valve unit 10 includes a cylindrical 
housing 21 of magnetic material which is integrally provided with the 
first outlet port 10b. The cylindrical housing 21 is also provided at its 
periphery with a radial pipe 22 forming the inlet port 10a and is closed 
at its open end by means of a cover member 23 of magnetic material in an 
air tight manner, the cover member 23 being integrally formed with the 
second outlet port 10c. Assembled within the cylindrical housing 21 are an 
annular air-filter 24 and a moving-coil linear motor 30. The linear motor 
30 comprises a longitudinal tubular core 31 air-tightly secured at its one 
end to an inner boss of housing 21 and at its other end to the inner wall 
of cover member 23. The tubular core 31 is provided at its inner shoulder 
with a partition member 40 which subdivides the interior of core 31 into a 
first passage P.sub.1 in open communication with the first outlet port 10b 
and a second passage P.sub.2 in open communication with the second outlet 
port 10c. 
The moving-coil linear motor 30 further comprises a bobbin 32 of 
non-magnetic material on which a moving-coil 33 is wound, and a pair of 
permanent magnets 38 and 39 which are fixed to the inner peripheral wall 
of housing 21 and opposed to each other. The bobbin 32 is axially slidable 
on the left-hand portion of tubular core 31, and the permanent magnets 38, 
39 are magnetized to provide the same polarity at their opposed inner 
faces so as to form magnetic flux perpendicularly to the moving-coil 33. 
Within an annular space around the right-hand portion of tubular core 31, 
there is provided a cup-shaped spring holder 34 of non-conductive material 
in which a pair of conductive compression coil springs 36 and 37 are 
concentrically assembled. The spring holder 34 is adjustable in its axial 
direction and opposes a flanged sleeve-like spring holder 35 of 
non-conductive material which is fixedly coupled over the right-hand 
extension of bobbin 32. The compression coil springs 36 and 37 are 
interposed between spring holders 34 and 35, and each of springs 36 and 37 
is connected at its left end to each terminal of the moving-coil 33 and at 
its right end to each terminal of a lead wire 50 through the base of 
spring holder 34. In addition, each right end of springs 36 and 37 is 
insulated within the spring holder 34. When an electric current is applied 
to the moving-coil 33 from an electric control circuit across lead wire 50 
and springs 36, 37, a linear force generates in proportion to the applied 
current by Fleming's left-hand rule to move the bobbin 32 in the rightward 
direction. 
To modulate the maximum flow quantity respectively across the first and 
second outlet ports 10b and 10c, the tubular core 31 is formed at the 
left-hand portion thereof with a plurality of equidistantly spaced axial 
holes 31a, and the bobbin 32 is integrally formed at the left-hand inner 
periphery thereof with a first annular valve part 32a. Thus, the first 
valve part 32a cooperates with the axial holes 31a to provide a first flow 
control valve V.sub.1 for controlling fluid communication between the 
inlet port 10a and the first outlet port 10b across the first passage 
P.sub.1 in accordance with the movement of bobbin 32 caused by operation 
of the linear motor 30. The tubular core 31 is further formed at the 
right-hand portion thereof with a plurality of equidistantly spaced axial 
holes 31b, and the bobbin 32 is integrally formed at the right-hand inner 
periphery thereof with a second annular valve part 32b. Thus, the second 
valve part 32b cooperates with the axial holes 31b to provide a second 
flow control valve V.sub.2 for controlling fluid communication between the 
inlet port 10a and the second outlet port 10c across radial holes 32c, 
35a, respectively formed in the bobbin 32 and spring holder 35, and the 
second passage P.sub.2 . 
In operation , when the moving-coil 33 is deenergized, the bobbin 32 is 
engaged at the left end thereof with the inner boss of housing 21 due to 
the biasing force of springs 36 and 37 such that both the axial holes 31a 
and 31b are fully closed by the valve parts 32a and 32b of bobbin 32. This 
results in interruption of each fluid communication between the inlet port 
10a and the first outlet port 10b and between the inlet port 10a and the 
second outlet port 10c. When the moving-coil 33 is energized by an 
electric current through springs 36, 37, the bobbin 32 is displaced 
rightwards against the biasing force of springs 36, 37 in accordance with 
a value of the current through moving-coil 33 so that each opening area of 
axial holes 31a and 31b is simultaneously modulated in accordance with the 
displacement of bobbin 32. Thus, the air flowing into inlet port 10a 
passes through the first flow control valve V.sub.1, first passage 
P.sub.1, and first outlet port 10b and is then supplied into the main 
air-bleed passage 84 of carburetor 83 through passage 91. Simultaneously, 
the air from inlet port 10a passes through the second flow control valve 
V.sub.2, second passage P.sub.2, and second outlet port 10c and is then 
supplied into the pilot port 86 of exhaust gas recirculation valve 85 
through passage 92. Consequently, the air flow into main air-bleed passage 
84 controls the air-fuel ratio in carburetor 83, and the air flow into 
pilot port 86 controls the pilot pressure in exhaust gas recirculation 
valve 85, causing adjustment of the operation of valve 85. 
From the above description, it will be understood that the flow control 
valve unit 10 acts to simultaneously control the air supply into two 
independent devices such as the carburetor 83 and the exhaust gas 
recirculation valve 85. It will be also understood that the flow control 
valve unit 10 can be manufactured with a low cost in a simple construction 
owing to provision of the first and second flow control valves V.sub.1 and 
V.sub.2 on the common tubular core 31. 
Although the flow control valve unit 10 is adapted to control the air 
supply into main air-bleed passage 84 of carburetor 83 and into the pilot 
port 86 of exhaust gas recirculation valve 85, it may be adapted to 
control the air supply into the main air-bleed passage and an air passage 
for slow speed control. In the practical use of the flow control valve 
unit 10 for various two independent devices, the valve parts 32a, 32b and 
axial holes 31a, 31b may be modified in their shapes and number to change 
the flow quantity control timing and ratio by the respective flow control 
valves V.sub.1 and V.sub.2. It is further noted that the control valve 
unit 10 may be modified in such a manner that the opening area of the 
second flow control valve V.sub.2 decreases in accordance with increase of 
the opening area of the first flow control valve V.sub.1. 
In the above description, while the fundamental features of the invention 
have been explained with reference to a specific embodiment, it will be 
understood that various omissions and substitutions in the device as 
illustrated may be made by those skilled in the art without departing from 
the spirit of the present invention.